Miracle-dz/UniFAR-FTUs huggingface dataset:
Cutoff Frequencies of a Dielectric-Loaded Rectangular Waveguide With Arbitrary Anisotropic Surface Impedance

The coupled transcendental equations describing cutoff frequencies of TE and TM modes are deduced for a rectangular waveguide with arbitrary wall impedance. In the case of TE modes, their generalization is made to a rectangular guiding structure, which possesses both distributed wall impedance and inhomogeneous dielectric loading. Effective impedance is obtained for imperfectly conducting surface incorporating periodic rectangular corrugations along the direction of mode propagation. Circular waveguide bounded by such corrugated surface and rectangular impedance waveguide are considered as numerical examples. For these waveguides, the computations performed to determine the cutoff frequencies of TE guiding modes are validated against the results of the perturbation theory and the finite-element method.
A Compact Reconfigurable Microstrip Antenna With Multidirectional Beam and Multipolarization

In this communication, a novel pattern and polarization reconfigurable microstrip antenna with a simple structure is presented. By switching four p-i-n diodes integrated with the antenna, the current distribution on the antenna can be altered, thereby changing the antenna performance. The proposed antenna can realize eight operating states of the radiation patterns including one boresight linear polarized (LP) pattern with narrow beamwidth, one boresight LP pattern with wide beamwidth, four directional LP patterns in the xoz plane and yoz plane, and one left-hand circularly polarized and one right-hand circularly polarized pattern with wide beamwidth. The operating frequency band of the antenna is from 3.1 to 3.45 GHz. An antenna prototype has been fabricated to validate the design concept. Good agreement between the simulated and measured results is found, and the cross polarization level is below −21 dB.
Power System Real-Time Emulation: A Practical Virtual Instrumentation to Complete Electric Power System Modeling

Hardware-in-the-loop (HIL) simulation is a technique that is being used increasingly in the development and test of complex systems. Real-world testing of an intricate system in a field-like power plant can be challenging, time-consuming, expensive, and hazardous. HIL emulators allow engineers to test devices thoroughly and efficiently in a virtual environment with high reliability and minimum risk of defect. In this paper, the complete electric power system (including generator, turbine-governor, excitation system, transmission lines, transformer, external grid and related loads) is implemented in a MATLAB/Simulink environment. Different virtual instrument pages are modeled in the graphical programming language of LabVIEW which enable fast and reliable measurement functions such as data acquisition, archiving, real-time graphical display and processing. The interaction between MATLAB and LabVIEW is accomplished by generating a Pharlap ETS Targets *. dll file which enables the two software to exchange real-time data. Also, a real 1518-kW excitation system is considered as a test case for the introduced HIL system. This equipment is connected to LabVIEW software through a National Instrument PXI technology. Different scenarios (electrical frequency/active power change, voltage step response, etc.) are simulated in the designed power system emulator (PSE). The validity of the implemented model for the excitation system is verified by finding good matching between MATLAB and HIL simulation results.
The Effects of Graphene on Microstructural and Thermal Properties of Calcium Chloride Hexahydrate PCM

Phase change materials (PCMs) are the excellent option used to store thermal energy as latent heat which substantially contribute to the efficient use and conservation of waste heat and solar energy. There are very few studies on nano enhanced inorganic PCM especially calcium chloride hexahydrate. Therefore, the aim of this paper is to examine the effects of graphene on the microstructural and thermal properties of calcium chloride hexahydrate. The thermal conductivity and morphology of pure PCM and nanoenhanced graphene PCM was investigated using Field emission scanning electron microscope (FESEM), Transmission electron microscope (TEM), 3D Laser microscope (LEXT), KD2 Pro thermal property analyser and Differential scanning calorimeter (DSC) methods. From the microstructural observation, a sharp single lattice fringe proved that graphene has uniformly dispersed with PCM and removed the stacking effect and agglomeration. The thermal conductivity and increased by 20% when 2wt% of graphene were mixed with calcium chloride hexahydrate. This nanoenhanced PCM is suitable for energy storage in solar thermal and photovoltaic thermal applications.
Performance Analysis of Distortion-Acceptable Cooperative Communications in Wireless Sensor Networks for Internet of Things

This paper analyzes the performance limit of cooperative communications in wireless sensor networks (WSNs), with the aim of utilizing the analytical results for practical applications, for example, Internet of Things (IoT). The observation of a primary sensor is not necessarily to be reconstructed losslessly, as long as the system can make correct judgements and operations. At first, we perform the theoretical analysis to derive an inner bound on the achievable rate-distortion region for the lossy communications with helpers. The numerical results precisely match the Wyner–Ziv theorem when there is only one assisting link and no rate constraint on the assisting link. Then, we present a distributed encoding and joint decoding scheme for cooperative communications in WSNs. Moreover, a series of simulations are conducted for the performance evaluation and verification. Although there is an obvious gap between the theoretical and simulation results, the performance curves show similar tendencies in terms of the signal-to-noise ratio versus bit error rate.
Discussion of Single-Stage Isolated Unidirectional AC-DC On-Board Battery Charger for Electric Vehicle

Nowadays, plug-in electric vehicles (PEVs) have been given wide concerns all over the world due to their merits over the fuel vehicles. Electric vehicle (EV) technology is equipped with a high efficient on-board battery charger (OBC). The battery charger converters are classified into three main types; integrated converter with the machine, two-stage and single-stage structure. These three types of OBC are usually compromised according to power factor corrector (PFC), cost, efficiency and lifetime. In this paper, a recent survey about the various available single-stage isolated unidirectional OBC systems are compared regarding to the previous four metrics. Moreover, hardware limitation, performance, and the utilization of the semiconductors are considered in this review. Finally, those topologies are summarized considering various performance criteria.
Reinvestigation of Single-Phase FLLs

Besides well-known phase-locked loops, frequency-locked loops (FLLs) are applicable to grid synchronization for grid-tied power converters. The models, principles, and algorithm structures of existing notch filter-based single-phase FLLs are often described with different theories in previous studies. Consequently, a theoretically unified understanding and further advancements of such type of FLLs are restricted. This paper reinvestigates notch filter-based single-phase FLLs and develops a generalized design framework for such types of FLLs. The model derivations of the FLLs are made uniformly via the Popov’s model reference adaptive control theory, in order to achieve the theoretically unified understanding. Three major contributions are received in this paper. First, a family of FLLs is derived, and existing seemingly different FLL designs are accordingly developed into a family of homologous FLLs. Second, the performance differences between the FLLs in the whole family are evaluated and compared quantitatively from the algorithm structure point of view, in terms of stability, convergence speed, and harmonic suppression capability. Finally, an enhanced single-phase FLL (named the $1\phi $ -EFLL) is recommended by the family of the homologous FLLs. The designs and the performance evaluations are verified by both simulations and experiments.
Effective Power Management of DC Microgrids Using Adaptive Droop Control

In this paper, an adaptive droop controller is developed for DC microgrids in order to balance the state of charge (SOC) for different connected batteries, and also to keep the bus voltage within the allowed limits. A methodology for sizing the photovoltaic (PV) system and battery bank is performed considering the daily energy consumption and the maximum load power. Then, the whole system is modeled using PSCAD/EMTDC simulation software. The PV control methodology is built to operate in either maximum power point tracking (MPPT) mode voltage droop control mode depending on the maximum SOC limit of batteries. The control methodology for batteries is built using droop-based power technique to balance SOCs of batteries in charging and discharging modes. Different case studies are investigated to validate the effectiveness of adaptive droop control in DC microgrids. The results ensured the success of the controller to achieve the required balance of the batteries SOCs and the effective power management in the system.
Bandstop Frequency-Selective Structures Based on Stepped-Impedance Loop Resonators: Design, Analysis, and Measurement

A new dual-polarized and dual-band second-order bandstop 3-D frequency-selective structure (FSS) is proposed with arbitrary band ratio. Compared with the square loop, the stepped-impedance (SI) loop resonator performs at lower basic resonant frequency and increases the first spurious resonant frequency. Different half-wavelength SI loop resonators are analyzed, compared, and employed to design single/dual-band 3-D FSSs under TE polarization. A double-sided SI loop resonator with via holes is presented for constructing a dual-polarized single band FSS. By adjusting widths of low characteristic impedance sections, the FSS’s band can be expanded into dual bands. Detailed analysis of the coupling between both identical resonators in series is provided for understanding the relationships between subresonators. In addition, the equivalent circuit models are developed to explain the operating principle and analyze parameter effects. The proposed FSS prototype is fabricated and then measured to verify the design methodology. The measured results agree with the simulated data and exhibit a dual-polarized and stable second-order bandstop response under different incident angles up to 30°. The thickness of the structure is 23% of the free-space wavelength at the first center frequency, and the center frequency ratio of both stopbands is only 1.08.
High power microwave system based on power combination and pulse compression of conventional klystrons

A high power microwave system based on power combination and pulse compression of conventional klystrons is introduced in this paper. This system mainly consists of pulse modulator, power combiner, driving source of klystrons and pulse compressor. A solid state induction modulator and pulse transformer were used to drive two 50MW S-band klystrons with pulse widths $4\mu\mathrm{s}$ in parallel, after power combination and pulse compression, the tested peak power had reached about 210MW with pulse widths nearly 400 ns at 25Hz, while the experimental maximum output power was just limited by the power capacity of loads. This type of high power microwave system has widely application prospects in RF system of large scale particle accelerators, high power radar transmitters and high level electromagnetic environment generators.
An Integrated Series-Parallel Microgrid Structure and its Unified Distributed Control

This paper presents an integrated series-parallel microgrid(MG), where a few distributed generation(DG) units in series type are used to form a DG string, then DG strings supply power to the common load in parallel type. With this structure, low-voltage devices could be integrated into MG without DC-DC boost converters. It provides a more flexible and efficient way to form higher voltage level MG. But it is difficult to find a decentralized control method to achieve power balance for this integrated system because of the difference between power transmission characteristics of parallel and series converter system. For this proposed MG in island mode, a unified distributed control strategy is proposed. With low bandwidth communication, accurate power sharing can be realized by exchanging information between the first converters connected to the bus of adjacent DG strings and between adjacent converters inside each DG string. Because the central controller is not used, the communication pressure of the system is reduced and the reliability is guaranteed. Simulation test has verified the feasibility and validity of the proposed control strategy.
A Hilbert Transform Equalizer Enabling 80 MHz RF Self-Interference Cancellation for Full-Duplex Receivers

A passive, time-domain equalizer is presented that achieves a broadband self-interference cancellation (SIC) over 80 MHz of RF bandwidth for simultaneous full-duplex radios. A baseband Hilbert transform technique reduces the number of equalizer taps needed for SIC, and with frequency translations, results in an equivalent RF-domain equalization. A proof-of-concept prototype in 0.13-<inline-formula> <tex-math notation="LaTeX">$\mu \text{m}$ </tex-math></inline-formula> CMOS process attains a measured 23 dB of SIC over an 80 MHz signal bandwidth at 900 MHz, and consumes 13 mW of clocking power independent of SIC equalizer settings. Its impact on the receiver noise figure is 1.4 dB. The equalizer and the receiver together consume 64.4 mW from a 1.2 V supply in an active area of 0.72 mm<sup>2</sup>.
Robust Sparse Linear Discriminant Analysis

Linear discriminant analysis (LDA) is a very popular supervised feature extraction method and has been extended to different variants. However, classical LDA has the following problems: 1) The obtained discriminant projection does not have good interpretability for features; 2) LDA is sensitive to noise; and 3) LDA is sensitive to the selection of number of projection directions. In this paper, a novel feature extraction method called robust sparse linear discriminant analysis (RSLDA) is proposed to solve the above problems. Specifically, RSLDA adaptively selects the most discriminative features for discriminant analysis by introducing the $l_{2,1}$ norm. An orthogonal matrix and a sparse matrix are also simultaneously introduced to guarantee that the extracted features can hold the main energy of the original data and enhance the robustness to noise, and thus RSLDA has the potential to perform better than other discriminant methods. Extensive experiments on six databases demonstrate that the proposed method achieves the competitive performance compared with other state-of-the-art feature extraction methods. Moreover, the proposed method is robust to the noisy data.
MMC-Based SRM Drives With Decentralized Battery Energy Storage System for Hybrid Electric Vehicles

This paper proposes a modular multilevel converter (MMC) based switched reluctance motor (SRM) drive with decentralized battery energy storage system for hybrid electric vehicle applications. In the proposed drive, a battery cell and a half-bridge converter is connected as a submodule (SM), and multiple SMs are connected together for the MMC. The modular full-bridge converter is employed to drive the motor. Flexible charging and discharging functions for each SM are obtained by controlling switches in SMs. Multiple working modes and functions are achieved. Compared to conventional and existing SRM drives, there are several advantages for the proposed topology. A lower dc-bus voltage can be flexibly achieved by selecting SM operation states, which can dramatically reduce the voltage stress on the switches. Multilevel phase voltage is obtained to improve the torque capability. Battery state-of-charge balance can be achieved by independently controlling each SM. Flexible fault-tolerance ability for battery cells is equipped. The battery can be flexibly charged under both running and standstill conditions. Furthermore, a completely modular structure is achieved by using standard half-bridge modules, which is beneficial for market mass production. Experiments carried out on a three-phase 12/8 SRM confirm the effectiveness of the proposed SRM drive.
Breaking the Limits of Subspace Inference

Inferring low-dimensional subspaces that describe high-dimensional, highly incomplete datasets has become a routinely procedure in modern data science. This paper is about a curious phenomenon related to the amount of information required to estimate a subspace. On one hand, it has been shown that information-theoretically, data in $\mathbb {R}^{\mathrm {d}}$ must be observed on at least $\ell =\mathrm {r}+1$ coordinates to uniquely identify an r-dimensional subspace that approximates it. On the other hand, it is well- known that the subspace containing a dataset can be estimated through its sample covariance matrix, which only requires observing 2 coordinates per datapoint (regardless of $\mathrm {r}! $). At first glance, this may seem to contradict the information-theoretic bound. The key lies in the subtle difference between identifiability (uniqueness) and estimation (most probable). It is true that if we only observed $\ell \leq \mathrm {r}$ coordinates per datapoint, there will be infinitely many r-dimensional subspaces that perfectly agree with the observations. However, some subspaces may be more likely than others, which are revealed by the sample covariance. This raises several fundamental questions: what are the algebraic relationships hidden in 2 coordinates that allow estimating an r-dimensional subspace? Moreover, are $\ell = 2$ coordinates per datapoint necessary for estimation, or is it possible with only $\ell =1$? In this paper we show that under certain assumptions, it is possible to estimate some subspaces up to finite choice with as few as $\ell =1$ entry per column. This paper raises the question of whether there exist other subspace estimation methods that allow $\ell \leq \mathrm {r}$ coordinates per datapoint, and that are more efficient than the sample covariance, which converges slowly in the number of data points n.
Heuristic Evaluation in Visualization: An Empirical Study : Position paper

Heuristic evaluation is a usability inspection method that has been adapted to evaluate visualization applications through the development of specific sets of heuristics. This paper presents an empirical study meant to assess the capacity of the method to anticipate the usability issues noticed by users when using a visualization application. The potential usability problems identified by 20 evaluators were compared with the issues found for the same application by 46 users through a usability test, as well as with the fixes recommended by the experimenters observing those users during the test. Results suggest that using some heuristics may have elicited potential problems that none of the users noticed while using the application; on the other hand, users encountered unpredicted usability issues.
Comments on “Digital Current Control in a Rotating Reference Frame—Part I: System Modeling and the Discrete Time-Domain Current Controller With Improved Decoupling Capabilities”

A recent paper by Hoffmann <italic>et al.</italic> presents a discrete-time model in a rotating <inline-formula><tex-math notation="LaTeX">$dq$</tex-math></inline-formula> reference frame of an <italic>R-L</italic> filter and its current control. The purpose of this note is, first, to show that the discrete model presented in the paper behaves differently to the sampled continuous-time model of the plant, formulated in the stationary <inline-formula><tex-math notation="LaTeX">$\alpha \beta$</tex-math></inline-formula> reference frame; second, to find the proper discretization of the plant in <inline-formula><tex-math notation="LaTeX">$dq$</tex-math></inline-formula> coordinates; and third, to verify that there is cross coupling between axes <inline-formula><tex-math notation="LaTeX">$d$</tex-math></inline-formula> and <inline-formula><tex-math notation="LaTeX">$q$</tex-math></inline-formula> in the closed-loop system if the original model is used, and that this coupling is not present when using the model found in this note. In the note, it is verified that having a precise model of the plant allows us to fulfill the control objective of obtaining the complete decoupling between axes.
Scheduling and Energy Management of Smart Homes Using Customer Choice Based Algorithm

In developing countries, reduction of energy consumption cost, load forecasting, scheduling and control on the utility side are the major concern towards energy management. In this paper, a solution to this problem is addressed using PERT (Program Evaluation and Review Technique) combined with CPM (Critical Path Method). It is a technique to obtain the best solutions for optimized scheduling of household appliances for Home Energy Management System (HEMS). The optimization is carried out with various constraints in the selected home environment. The state of this condition is considered as a Mixed Integer Linear Programming (MILP) problem with more complexity. To reduce the complexity of this problem, it is solved in two stages namely, a grouping of appliances and selection of optimized group. The simulation of scheduling the appliances with all necessary inter dependencies is carried out using the proposed technique which is named as Customer Choice Based Algorithm (CCBA). The input data for simulation are considered from the existing methods and its results and performance are compared with the proposed algorithm. The proposed technique has effectively managed the peak demand and reduces the cost of energy consumption.
The Best Practice of University and Community Cooperation in Open Source Software Project - TV Station Media Images Query System for Example

One open source software project, Open Source Technology Development and Cultivation of Talent, of Institute for Information Industry (III), Taiwan released an opportunity and gave us a valuable practice in helping some engineers, students, and teachers to work together. In this project, we try to develop the TV station media images query system prototype. Face recognition based on videos or image sets has been involved in the project. We try to apply Convolutional Neural Networks (CNN) and perform feature extraction on a target face in multiple image frames of given videos and generate multiple face feature vectors respectively. This proposed prototype and flowchart try to convert the plurality of face feature vectors into a feature vector of a predetermined dimension and judge the feature vector of the predetermined dimension by using a classifier to recognize the target face. The user can input Chinese name of actress and pressure search button, then, if information retrieved from the database associated with a selected person, it can show all similar images and time associated with a given face name.
A Ka-Band Wideband SIW Cavity-Backed Slot Antenna Array

A wide band substrate integrated waveguide (SIW) cavity-backed antenna operating in Ka band is presented in this paper. The proposed SIW cavity is octagonal with two trapezoidal slots on it. Additional substrate is added upon the cavity as an impedance transformer. Then a $2\times 2$ antenna array is designed to further increase the antenna gain. Simulated results demonstrate that the $\vert \mathbf{S}_{11}\vert < -10\ \mathbf{dB}$ impedance bandwidth of the proposed antenna reaches 30.2% (23.0-31.2 GHz), and the antenna array achieves 20.2% (24.5-30.0 GHz) impedance bandwidth and stable gain throughout the operating bandwidth with a peak of 13.8 dBi.