Miracle-dz/UniFAR-FTUs huggingface dataset:
Photoemission of Semiconductor Photocathodes for current quantization

The SI system was redefined, and the ampere was defined based on the elementary charge of a single electron. Different devices have been studied to conform to the new definition for practical application. In contrast with a single-electron transistor (SET) that can count individual electrons, a photocathode electron gun-based device that measures a group of electrons is being proposed, which can provide large current several orders higher than SET. A photocathode is an electron source that plays a critical role in the device. This paper studies the photocathodes' photoemission process and quantum efficiency (QE). A revised theoretical expression of QE has been obtained, which agrees well with the simulation and experimental data. It covers the photoemission situation from minimum to saturation with different thicknesses of the buffer layer.
Transient elastography at very high ultrasound frequencies

Elastography is a quantitative ultrasound (US) technique used to obtain soft tissue stiffness maps. This technique is based on two key concepts: generating shear waves (SW) of which their speed is linked to stiffness and imaging the propagation of these SW with a high frame rate. This technique is routinely used in clinic by using the shear wave elastography (SWE) method where SW are commonly generated by acoustic radiation force at low-medium US frequency (between 3 and 15 MHz). At higher frequencies the energy deposit of the US beam is too low to create a force due to the low voltage applied on high frequency arrays. In this work, a mechanical vibrator, coupled to an ultrafast and US high frequency device (Vevo F2, Visualsonics), is used to generate shear wave. It shows the capability of this device to catch propagation of SW, leading to strong improvement in the spatial resolution of stiffness maps at US frequencies higher than 15 MHz.
Research on the Properties of Optical Transition Radiation in HUST-FEL

Bunch length is one of the key longitudinal parameters in beam diagnostics, a bunch length measurement system is urgently needed to monitor the variation of bunch length in HUST-FEL. Based on a thorough investigation, we propose a measurement system using streak camera based on the optical transition radiation (OTR). We discuss the classical theory of the transition radiation (TR) in HUST-FEL in detail, simulate the angular distribution of TR at different beam energies, and select the TR target material from the perspective of economy and practicability. Considering about the practical application, we also discuss the effects of finite size target and pre-wave zone of TR based on the Weizsäcker-Williams method of virtual photon.
Design and Evaluation of a 1200-V/200-A SiC Three-Level NPC Power Module

The silicon carbide (SiC) power module is one of the most popular semiconductor devices in industrial applications with the enhanced current rating. In this paper, a 1200-V/200-A SiC three-level (3L) module with neutral point clamped (NPC) topology is designed and validated. Based on the simulation and experiment results, it can be found that the maximum internal commutation loop stray inductance is no more than 40 nH, and the total switching loss can be reduced more than 30% compared with the hybrid 3L NPC module (Si IGBTs+SiC SBDs). Meanwhile, the power loss evaluation demonstrates that the designed 3L NPC module with all-SiC device is more suitable for high-voltage and high-frequency applications compared with its 2L counterpart. In addition, the thermal simulation shows that the maximum junction temperature is less than 120°C when the module operates as a buck converter with $V_{DC}=600\ \mathrm{V}, I_{o}= 150\ \mathrm{A}$, and $f_{s}=100\ \text{kHz}$.
FPGA-based Algorithm for Harmonic Current Mitigation

The present paper deals with problems related to the damaging effect of nonlinear loads that expressed in harmonic current, where we proposed an instantaneous calculation of the sinus and cosine functions related to the fundamental frequency using a multi-variable filter (FMV). The main idea is to go beyond the limits caused by the use of PLL so as to extract instantaneously and precisely the fundamental component of the voltage of the power system. To do that the FMV algorithm is implemented on the FPGA and the Newton-Raphson algorithm is depicted in order to calculate the needed inverse square root where the obtained sine and cosine functions are used to optimize the instantaneous imaginary power algorithm for extracting the harmonic components. Simulations and exprimental results are performed to demonstrate the effectiveness of the proposed study.
Effect of Moisture on the Electrical Treeing Characteristics in ER and ERIP

Epoxy resin (ER) and epoxy resin impregnated paper (ERIP) are commonly used insulation materials, playing important roles in the field of power equipment and electrical equipment. However, moisture has a significant impact on ER and ERIP insulation performance. To research the effect of moisture on the electrical treeing characteristics in ER and ERIP, the experimental platform of treeing at AC-temperature was established. The needle electrodes were cast into the samples with the gap of 2 mm. Electrical treeing experiments were conducted on moist and non-moist ER, ERIP samples at 16 kV AC at 60°C respectively. The results show moisture has little effect on the initiation of electrical trees. For the EP samples, the moisture results that the breakdown time of samples reduces. For the ERIP samples, the moisture prompted the morphology of the trees changing from branch like to bush like, which rarely occurring in the ERIP samples. The density of the trees increases and the fractal dimension increases significantly. The samples do not breakdown for more than 10 h. This may be due to the shielding effect of the defects. The results of this paper may help to explore the life of insulating materials and may provide a reference for the optimal design of insulation materials.
Fast Imaging of Crack Defects in Pipes Using Fourier-Domain Migration

Plane-wave imaging (PWI) techniques have been shown to be highly effective in ultrasonic nondestructive testing (NDT) applications. This work explores PWI of liquid-filled steel pipes using an immersed transducer array. We want to ascertain the presence of backwall surface cracks by reconstructing the pipe image from the reflection data. This is challenging because the pipe's frontwall and backwall surfaces are not flat. To achieve our objective, we propose a low-cost approximate beamforming method based on Fourier-domain migration that can be used for fast initial pipe assessment.
Laser Diode Beam Shaping and Homogenization with a Multimode Fiber applied to Optical Resolution Photoacoustic Microscopy based on Linear Phased Array Ultrasound Probe

Pulsed Laser diodes stacks (PLD) are a promising low cost option as laser sources for Optical Resolution Photo acoustic Microscopes (ORPAM). Nevertheless, their multimode beams with wide divergences and non-uniform light distributions, imposes limitations to the lateral resolution that can be achieved at a long laser focusing distance needed for clinical applications. Here, it is devised a new strategy to attain high lateral resolutions at a centimeter-long working distance, based on coupling the PLD power into a square core multimode optical fiber. An ORPAM system with an ultrasound linear phased-array in reflection confocal mode was built to test its performance.
Experiments of SiC MOSFETs in high DC bus voltage Boost applications

In high power DC-DC or AC-DC, there is a trend towards increasing the DC bus voltage. In this paper, two boost converter of 1300V DC bus are studied. In the circuit design, a new 2000V SiC MOSFET and a conventional serial-connected 1200V devices are used to achieve a 1300V DC bus requirement. The analytical calculations and experimental results show that the topology of 2000V devices can achieve higher efficiency and power density compared with topology of conventional serial-connected 1200V devices. The implementations of two topologies of boost converters are discussed and the advantages of 2000V SiC MOSFETs for high DC bus voltage applications are demonstrated experimentally.
A Robust Primary-Side Hybrid Data-driven Load Monitoring Strategy for Wireless Power Transfer Systems

Conventional front-end load monitoring strategies for wireless power transfer (WPT) systems are designed based on circuit models, which may not be accurate when the system parameters drift or measurement errors occur. In this paper, a primary-side hybrid data-driven load monitoring strategy is proposed to address this issue, while still maintaining the merit of non-communication between the transmitter and receiver. The hybrid data includes both simulation and experimental data. The simulation data can be rapidly acquired in large numbers and the experimental data can reflect disturbance. The hybrid data are used for training a Multilayer Perceptron (MLP) with one input layer, six hidden layers, and one output layer. The proposed MLP is validated to be more accurate than the conventional circuit models for monitoring load conditions of practical WPT systems with disturbance.
Optimization of Edge Profile for Improved Anti-Resonance Quality Factor in Lithium Niobate SH0 Resonators

Thin-film lithium niobate (LNO) has been identified as a promising material platform for enabling high electromechanical coupling and low-loss piezoelectric resonators for filtering applications. In this work, the design and fabrication of fundamental shear horizontal (SHO) mode resonators with a resonance frequency of 1.1 GHz are reported. Initial devices show high losses leading to low quality factor at anti-resonance due to undesired redeposition debris originating from Ion Beam Etching (IBE) of the resonator sidewalls. Methods to improve the quality of the resonator sidewalls and minimize those losses are presented. With those improvements, SHO resonators with high electromechanical coupling $(k_{eff}^{2}$ = 28%) and impedance ratios larger than 104 could be achieved.
Evaluation of lateral and axial resolution of pixel-based beamformers in photoacoustic tomography using a linear US probe

Many photoacoustic tomography (PAT) systems have been developed using conventional linear ultrasound probes with reduced angular spectra, which limits the resolution of tomographic reconstructions. These limitations are partially compensated by employing advanced reconstruction algorithms that take advantage of the intrinsic characteristics of the photoacoustic signals. The aim of this work is to theoretically, numerically and empirically characterise the lateral and axial resolution using two nearby point objects that are separated until they can be distinguished as two independent sources in the reconstructed image. It is also intended to study the effect of the main limitations of linear probes (geometry, frequency response and angular spectrum) on the spatial resolution. The results of this study shed light on the suitability of using each type of algorithm depending on the limiting conditions of the probe used and the imaging objective.
Synthesis Approach to Ladder-DMS Mixed Structures

Due to the need of wider bandwidths with the deployment of 5G-NR such as the cases of bands n77 and n79, there is a growing interest in the design of structures combining acoustically-coupled with electrically-coupled resonators. These mixed structures have the advantages of both configurations, having the great selectivity of a ladder topology with electrically coupled resonators, but being less reliant on the pole-zero distance of the resonator impedance to achieve higher bandwidths. Based on the resonances present in a Double-Mode SAW (DMS) resonator, this works presents the equivalent circuital and nodal representations of the DMS for the synthesis of ladder-DMS hybrid structures.
A comparative study of self-heating effects in 3nm node GAAFETs and FinFETs

In this paper, the three-dimensional 3nm node transistors are calculated by electro-thermal coupling using the TCAD simulation platform, and the thermal response characteristics of FinFETs and GAAFETs are analyzed and compared using the three-dimensional finite element simulation software. Besides, the heat dissipation path of the device is analyzed to provide guidance for the subsequent research.
Substation Digital Twin Framework Design and Key Technology Research

Digital twin (DT) is a key technology to improve the digital and intelligent level of substation operation and maintenance. In order to accelerate the application of DT in substations, this paper deeply studies the framework structure and key technologies of the substation DT. First, combined with the operational characteristics of substation, a five-dimensional DT model is proposed, which consists of physical entities of substation, digital models of substation, twin service, twin datasets, and the connection among the parts. Secondly, the framework structure for realizing the substation DT is designed, including device layer, perception layer, network layer, platform layer and application layer. Finally, the key technologies of substation DT are analyzed, and three technical aspects are elaborated from the application of 3D digital model fusion, the construction of substation lightweight digital model, and the interaction between data middle platform and application layer based on multi-agent.
Comparative Study of Flux-Switching Machines with T-Array and U-Array Permanent-Magnet Arrangements

This paper presents the comparison of two flux-switching (FS) machines with U-array and T-array permanent-magnet (PM) arrangements, termed as U-FSPM and T-FSPM, respectively. The topology evolution of U-FSPM and T-FSPM are illustrated based on an existing consequent-pole FSPM. By using the air-gap field modulation theory, the analytical model of the U-FSPM and T-FSPM are built and comparatively investigated. The harmonic analysis of the U-FSPM and T-FSPM are carried out, based on which the differences of working harmonics distributions of these two FSPMs are compared. The electromagnetic performances of the U-FSPM and T-FSPM are compared by finite-element analysis (FEA). It is found that the T-FSPM exhibits higher torque density and better overloading capability than U-FSPM. Finally, a prototype of T-FSPM is manufactured for experimental verification.
IPOCIM: Artificial Intelligent Processor with Adaptive Ping-pong Computing-in-Memory Architecture

Computing-in-memory (CIM) architecture is a promising solution toward energy-efficient artificial intelligent (AI) processor. Practically, the AI processor with CIM engine induces a series of issues including data updating and flexibility. For instance, in AI-oriented applications, the weight stored in the CIM must be reloaded due to the huge gap between limited capacity of CIM and growing weight parameter, which greatly reduces the computation efficiency of the AI processor. Moreover, the natural parallelism of CIM leads to the mismatch of various convolution kernel sizes in different networks and layers, which reduces hardware utilization efficiency. In this work, we explore a CIM engine with a ping-pong strategy as an alternative to traditional CIM macro and weight buffer, hiding the data update latency to enhance data reuse. In addition, we proposed a flexible CIM architecture adapting to different neural networks, namely IPOCIM, with a fine-grained data-flow mapping strategy. Based on the evaluation, IPOCIM achieves 1.4-7.1× performance improvement, and 2.2-6.1× energy efficiency, compared to baseline.
Quasi–modes of a weakly curved waveguide

Wave propagation in slowly varying guiding geometries is of fundamental importance across many disciplines, and can be described in terms of mutually uncoupled quasi‐modes. These are a generalization of the concept of normal modes in a uniform waveguide to the weakly non‐uniform case. Quasi‐modal propagation is dependent upon the wavelength and two geometrical length‐scales, those of the longitudinal variations and the guide thickness. By changing these length‐scales one enters different asymptotic regimes. Our aim is to present an asymptotic theory for quasi‐modal propagation, in the various regimes, and for a canonical geometry, that is, an arbitrarily curved waveguide of constant thickness. Potential applications of our results are very wide and include acoustic or electromagnetic propagation in curved waveguides, shear horizontal wave propagation in curved elastic plates, and the determination of electronic states in quantum wires. We derive practically useful asymptotic expressions of the quasi‐modes of a weakly curved waveguide; these are particularly important since the adiabatic approximation for this problem simply coincides with the normal modes of a straight waveguide of the same thickness. The basic ideas and methodology should carry across to other geometries, boundary conditions and governing equations.
Synthetic Aperture High Quality B-mode Imaging with a Row-Column Array Compared to Linear Array Imaging

Row-column (RC) matrix probes can yield 3-D volumetric imaging using a number of receiving elements similar to traditional linear arrays for commercial scanners. Some doubts have, however, been raised on the B-mode image quality of RC probes. It is hypothesized that synthetic aperture (SA) RC imaging can yield a better volumetric resolution than commercial spatially translated linear arrays, and at the same time attain volume rates similar to frame rates for single slice linear array scanning. A Vermon 6 MHz $128\times 128$ elements RC array with $\lambda$ pitch was used on a Verasonics Vantage 256 scanner. A SA sequence with $2\times 96$ emissions on the rows and columns and reception on all 128 orthogonal elements were employed giving a 62.5 Hz volume rate for a pulse repetition frequency of 12 kHz. The resolution and contrast were compared to an optimized SA sequence for a 256-elements GE L3-12D 6 MHz linear array probe, where the volume was acquired using a linear probe translation in the elevation direction. Imaging was conducted on a 3-D printed point spread function (PSF) phantom with scattering voids in a $6\times 4\times 4$ grid with a 2.05 mm spacing in all three directions. The exposed kidney of a Sprague-Dawley rat was also scanned in vivo with the RC probe. B-mode images of the 3-D printed PSF phantom were shown with a 40 dB dynamic range along with the linear array scans. An isotropic resolution of $(1.05\lambda, 1.10\lambda,0.62\lambda)=(x, y, z)$ was obtained for the row-column probe. The linear array probe had an elevation resolution determined by the geometric elevation focus of the array, and therefore the four rows of point scatterers could not be differentiated in the elevation direction due to the fixed elevation focus. The data rates were identical for the two arrays, but the RC array yielded an isotropic PSF with an improved contrast, and a 62.5 Hz volume rate comparable to normal linear array imaging. In vivo kidney images for the three orthogonal planes were shown with a 60 dB dynamic range demonstrating the isotropic speckle pattern in all three directions for all depths. The SA imaging RC sequence thus yielded a PSF independent of orientation and depth. Any slice plane in the volume therefore had a uniform speckle pattern, contrast, and resolution, demonstrating that RC arrays can yield higher quality B-mode images than linear arrays. The penetration depth of the probe and sequence was also measured to be $550\lambda$ corresponding to 141 mm.
Inverted Pulse Estimation in Pulse Inversion Harmonic Imaging using Deep Learning

Conventional methods such as filtering and multi-pulse acquisition techniques play an important role in ultrasonic nonlinear imaging, specifically harmonic imaging. However, the former suffers from spectral leakage, while the latter is hindered by the low frame rate and increased susceptibility to motion artifacts caused by the need to transmit two or more pulses. In this work, deep learning concepts are exploited to achieve a single-shot harmonic imaging application. This is accomplished by implementing an asymmetric convolutional autoencoder, capable of learning the nonlinear relationship between the echo resulting from the first transmitted pulse (network input) and the echo resulting from the second transmitted (inverted) pulse (network output) used in the conventional pulse inversion technique. The proposed approach yielded harmonic images with comparable contrast to noise and contrast ratios to the conventional pulse inversion technique, yet at approximately double the frame rate. These findings pave the way for harmonic imaging to be used with quality that is on par with the quality achieved by current harmonic imaging methods but with a higher framerate and fewer motion artifacts.
Self-assembling and ordering of Ge/Si(111) quantum dots: scanning microscopy probe studies

In order to exploit the unique electronic properties of semiconductor quantum dots (QDs) in novel quantum effect devices, the lateral dimensions of these structures have to be reduced to the order of tens of nanometres, which is the range of the de Broglie wavelength of electrons inside these materials. Moreover, millions of QDs should be packed in an orderly fashion in dense arrays to achieve the necessary active volume. So far, the most promising quantum structures have been fabricated using techniques based on direct crystal growth. This process has become very important due to its potential for creating damage-free and coherent nanocrystals. New scanning microscopy probes, such as scanning tunnelling microscopy and atomic force microscopy, are actually the most important analytical tools for checking the properties of these nanostructures. In the present paper we will review some of the results recently obtained on the Ge/Si system thanks to these techniques. Ge/Si is really appealing for future applications, in view of the integration of nanostructures with the present microelectronic technologies, but it is also at the origin of many general studies regarding atomic diffusion, intermixing, and island shape stabilization. The origin of the islands, their size and shape evolution, and the intermixing at the interface will be analysed starting from SPM data. The ordering of QDs on naturally or artificially nanostructured surfaces is one of the most recent objectives in Ge/Si research. For example, terraces created from the step bunching process on the Si(111) surface could be a way of controlling the spacing of the islands. Other possibilities are now opened by the increasing precision of electron-beam lithography and by new focused-ion-beam machines. These aspects, along with problems and drawbacks of self-assembling technology, will also be discussed.
Is Twitter an Echo Chamber? Connecting Online Public Sentiments to Actual Results From the 2019 Philippine Midterm Elections

Social media platforms like Twitter can act as a gateway towards understanding people's perspectives and viewpoints during national-level events such as elections. As such, one can estimate how likely a certain candidate's turnout would be in an election from reading targeted sentiments published online. In this study, we collected tweets during the 2019 Philippine midterm elections for senatorial positions and performed cluster-based analysis via k-means paired with SHAP to understand the winnability of a candidate with respect to associated words linked to them on Twitter. Results show multiple cases where candidates have won despite amassing extremely negative comments online.