Miracle-dz/UniFAR-FTUs huggingface dataset:
A Self-Tuning Notch Filter based Hybrid Active Damper for LCL-Type Grid-Tied Inverters with Adaptability to Weak Grids

$LCL-$ filters are widely used in grid-tied converters for improved attenuations and lower costs. To prevent instability, the $LCL$ resonance peak needs to be damped by the active dampers that avoid the dissipations but increase the control complexity. In the weak grid, the harmonic currents and the grid impedance variations make the control become more complicated and difficult. The influence of the harmonic currents and the grid impedance in parallel system is researched in this paper. Then, a self-tuning notch filter (STNF)is introduced, and the resonance peak identification process implemented in digital controller is proposed in detailed. The consumption and tracking error of the STNF are analyzed guaranteeing an effective design. By adopting the STNF, the local maximum gain frequency is estimated online in response to the grid inductance variations. The construction as well as optimal design principles of the hybrid active damper are proposed in detail. To further reject the harmonic voltage effects, a PR regulator with a harmonic compensation controller is adopted. A step-by-step example design of the controller is illustrated in detail. The online implementation in DSP controllers and the digitization influence of the proposed method are also amply discussed. Finally, simulation and experimental results verify the effectiveness of the proposed method.
PUF-Enabled Authentication-as-a-Service in Fog-IoT Systems

Fog-IoT systems enable to distribute computing, control, storage, and networking functions closer to edge devices, in order to improve efficiency and reduce latency. In order to cope with the multitude of security issues raised by the lack of centralized control and by the exposure of user sensitive data, suitable security solutions must be devised to protect data and thwart malicious attempts to compromise and take control over communication. In this paper, we propose a mutual authentication scheme relying upon the adoption of Physically Unclonable Functions (PUFs), which enables fog nodes and resource-constrained IoT devices to mutually prove their respective identities during communication, while meeting the existing low resource consumption requirements. The scheme is partially offered in an as-a-service fashion, thanks to the adoption of a cloud automation framework that facilitates its set-up on fog nodes.
A Phase-Shift Full-Bridge Converter with Novel Voltage Oscillation Clamping Circuit for Electric Vehicle on-Board Charger

In this paper, a novel clamping circuit is proposed to solve the voltage oscillation problem of the phase-shift full-bridge converter for electric vehicle on-board charger. The proposed clamping circuit, consist of a single capacitor, suppresses the voltage oscillation of the secondary diodes. Besides, this clamping circuit can reduced output filter because it applies the voltage to the output inductor even in the freewheeling period. Therefore, the proposed converter can achieve high efficiency by utilizing the higher performance diode and achieve high power density by the simple clamping circuit and reduced output filter. In the proposed clamping circuit, the amount of voltage oscillation reduction is determined by the ratio of the leakage inductors. Thus, in this paper, the design guideline of leakage inductances is also provided. The feasibility of the proposed converter has been verified with the experimental results under 270–420 VDC output voltage range at 3.3kW.
Methodology for Performance Optimization in Noise- and Distortion-Canceling LNA

This paper proposes a general methodology for designing noise-canceling low noise amplifiers (LNA). The procedure provides designers a more accurate information of the topology trade-offs in the technology and which restrictions must be imposed to design variables to attain target specifications. Thus, it is especially desirable when opposite specification, such as cut-off frequency, linearity, noise figure or power consumption are required. A CG-CS LNA in a 45 nm SOI CMOS technology is presented, although authors give guidelines to extrapolate the method to other topologies and technologies.
Development and Control of a Differential Wall Climbing Robot based on Vortex Adhesion

In this article, the development and control of a novel differential drive Vortex Robot (VR) will be presented. Towards the direction of developing a climbing robot for inspection and repair of large infrastructures, a lightweight reliable climbing robot is proposed, being able to carry high payload via an Electric Ducted Fan (EDF) vortex based adhesion actuator. Towards these objectives, the fundamental elements of the overall design will be presented. For the preliminary evaluation of the proposed system, a PID-based control architecture will be analyzed and experimentally evaluated, with the goal of controlling the locomotion properties of the VR, while achieving a constant adhesion regardless the orientation of the robot and the surface's inclination. To further evaluate the robot's efficiency in real-life scenarios, such as the inspection and repair of airplane structures, results acquired via field trials involving a full-scale Boeing 737 will be presented.
Conical structures on the surface of a liquid with ion current in the space-charge limited mode

Conical structures arising on the surface of a liquid with ionic conductivity in an electric field are considered taking into account the influence of both bulk and surface charges. It is demonstrated that the field distribution problem admits an exact analytical solution corresponding to the space-charge-limited current mode. The dependence of the saturation current through the conical formation on the cone apex angle, on the dielectric constant of the liquid, and on the mobilities of positive and negative ions is found. The current vanishes at zero and Taylor’s (49.3°) cone half-angles, and reaches the maximum value between them. The maximum current is shifted to higher angles with increasing dielectric constant of the medium.
A Low-Loss Three-Pole Frequency-Agile Bandpass Filter with Constant Absolute Bandwidth

In this letter, a three-pole frequency-agile bandpass filter (FA-BPF) with three transmission zeros (TZs) is presented. Based on the element variable coupling matrix (EVCM), the FA-BPF consists of two varactor-loaded quarter-wavelength resonators and one half-wave length resonator with varactors loaded at the specific position from the shorted-end. By adjusting the stub length from loading position to the shorted-end and the specific coupling length between resonators, the required coupling coefficients can be obtained for the FA-BPF with constant absolute bandwidth (CABW) and predefined frequency tuning range (FTR). To improve the frequency selectivity of the FA-BPF, the cross-coupling is realized for the topology of the filter, and thus a transmission zero (TZ) appears on the edge of passband. Besides, the source-load coupling is also introduced to generate two TZs to enhance the stopband rejection level. For demonstration, the FA-BPF is designed, fabricated and measured. The measurement results show that a great agreement with simulation results based on the proposed method.
Causes of Success in the La Liga and How to Predict them

The Spanish premier football league, La Liga, is consid-ered by many as the best and most exciting league in the world. With Spanish clubs dominating the most competitive tournament in European football, the Champions League, with 18 wins since its inception in 1955, the La Liga draws the attention of hundreds of millions of fans from around the globe. In this article, we use data mining techniques on historical data to predict results, as well as discover what causes some teams to be more successful than others. The goal is to provide predictions with higher certainty than the existing statistical models, and to discover interesting and useful patterns in European Leagues.
Chipless RFID Sensor Tag for Angular Velocity and Displacement Measurement

A novel chipless RFID sensor tag is investigated for angular velocity and displacement measurement. The designed sensor tag consists of horizontal and vertical I-shaped bar resonators which are both symmetrically arranged. The whole of the longest resonators acts as a sensing element while the others are used as encoders. The angular variation can be detected by measuring the Radar Cross-Section (RCS) magnitude of the sensing element as the object, to which the tag is attached, rotates. Meanwhile, a depolarizing technique is applied, which makes the detection process more robust. In addition, due to the fact that the dual polarization (DP) can increase the encoding capacity doubly in the same frequency band, the proposed tag with a compact dimension of 22 × 30 × 0.8 mm3 can encode 18-bit data. As compared with angular displacement and velocity sensors based on inductive coupling modulation, the proposed sensor tag can make a significant increase of the sensing distance.
Proposal of the Concept of a Breathing Assist System for Saxophone Players with Breathing Problems

This research aims to propose the concept of a breathing assist system for saxophone players with breathing problems. First, the quantity of pressure and air flow rate required to play an alto saxophone is determined by certain investigations and experiments. Second, the above-mentioned concept, which works like a pneumatic master-slave amplifier, is proposed and the details of each component are explained.
FT–IR Saliva Profiling in Patients with Obesity and Obesity–Related Insulin Resistance

Metabolic disorders such as type 2 diabetes mellitus, obesity and metabolic syndrome have a high incidence in the population of developed countries and require continuous clinical and pharmacological treatments throughout their progression. Obesity is associated with insulin resistance in over 90% of patients, but a small percentage of obese subjects are "protected" from this condition. Infrared spectroscopy has been investigated as a non–invasive tool on biofluids, together with signal processing techniques, in the research of novel and predictive biomarkers. In the following, a study based on saliva profiling using infrared spectroscopy on a population of metabolic abnormal and normal obese compared with control subjects is presented. Analysis has been carried out to design a consistent and standardized protocol for saliva profiling in different molecular regions of interest. Results obtained through an unsupervised classification technique allowed the grouping of patients belonging to a specific population on the basis of the characteristic molecular signatures in the regions of Amide I, glucose and thiocyanate.
Neural Encoder-Decoder based Urdu Conversational Agent

Conversational agents have very much become part of our lives since the renaissance of neural network based "neural conversational agents". Previously used manually annotated and rule based methods lacked the scalability and generalization capabilities of the neural conversational agents. A neural conversational agent has two parts: at one end an encoder understands the question while the other end a decoder prepares and outputs the corresponding answer to the question asked. Both the parts are typically designed using recurrent neural network and its variants and trained in an end-to-end fashion. Although conversation agents for other languages have been developed, Urdu language has seen very less progress in building of conversational agents. Especially recent state of the art neural network based techniques have not been explored yet. In this paper, we design an attention driven deep encoder-decoder based neural conversational agent for Urdu language. Overall, we make following contributions we (i) create a dataset of 5000 question-answer pairs, and (ii) present a new deep encoder-decoder based conversational agent for Urdu language. For our work, we limit the knowledge base of our agent to general knowledge regarding Pakistan. Our best model has the BLEU score of 58 and gives syntactically and semantically correct answers in majority of the cases.
River-water Quality Exploration

We describe our analysis of VAST Challenge 2018 Mini-Challenge 2 data set using a collection of visualization tools. We used the tools for better user interaction and to introduce new views in support of visual analytics. We answer some of the challenge questions and plan further research on data exploration and analysis based on the newly introduced data model, interaction, and views.
Low SWaP, In-Situ Data Logger for Strain Measurement of Paddlefish Rostrums in Motion

An embedded strain gage data logger has been developed by the Engineer Research and Development Center (ERDC) to facilitate data collection for an in-situ experiment investigating the strain and acceleration encountered by the paddlefish rostrum as it swims. This unique application has required a focus on reducing the size, weight, and power (SWaP) of the system. The accomplishments explained in this paper are the integration of a custom strain gage amplifier with a microcontroller and the verification of a linear relationship of the strain measured by this device with a calibrated professional desktop system. The mean and standard deviation errors between the expected values of the calibrated commercial system and the data logger from this experiment are −7/. 7 × 10−14 μϵ and 14.3 μϵ respectively.
Towards the Automatic Tuning of Linear Controllers Using Iterative Learning Control Under Repeating Disturbances

In this paper, iterative learning control (ILC) is proposed as an alternative approach that can be used to simplify the design of linear controllers for rejecting repetitive disturbances affecting a system. Since ILC is a data-driven method, its usage allows rejecting repetitive disturbances without a priori knowledge of their nature. The benefits of ILC appear especially when a system is subject to complex repetitive disturbances. This is simply because it would require a control designer to spend much more efforts to obtain similar results applying a state augmentation by building models for the same disturbances (Internal-Model-Principle based control). Accordingly, this paper first shows the equivalence of performing state augmentation and applying ILC in case of a simple sinusoidal repetitive disturbance. Next, a workflow named Learning Based Controller Tuning (LBCT) is proposed to simplify the parameter tuning of linear controllers under repetitive disturbances. The feasibility of LBCT is analysed by testing the ILC on a system subject to complex repetitive disturbances in two different forms: linearly combined sinusoidal signals and non-linearly combined sinusoidal signals. The results demonstrate that ILC can successfully learn the required controller parameters to reach a good rejection performance against the repetitive disturbances without a need of modelling them. This supports the fact that the tuning of linear controllers may be automated by integrating an ILC to the system.
A Pair of Parallel Differential Magnetic-Field Probes with High Spatial Resolution and Wide Frequency Bandwidth

Magnetic-field probes can be used for electromagnetic interference (EMI) measurement of high-speed circuits. The main probe performances include sensitivity, spatial resolution and bandwidth. To improve the spatial resolution and bandwidth, the size of probe loop must be made small. However, small loop size will result in low sensitivity. In this paper, a pair of differential magnetic-field probes is proposed to improve spatial resolution without reducing sensitivity. The proposed differential probes consist of two asymmetric loop probes, which are designed in the same plane and separated by a row of periodic vias. High spatial resolution can be achieved by measuring difference between the outputs of the two probes. The differential probes are designed under low temperature co-fired ceramic (LTCC) process. The simulation results show that the maximum operating frequency is 15GHz and the spatial resolution is 0.36mm.
Constant Load Voltage Characteristics in a Parallel-Parallel-Compensated Wireless Power Transfer System

This paper discusses load voltage characteristics in a parallel-parallel-compensated wireless power transfer (WPT) system. In this paper, the load voltage characteristic is analyzed at three resonant frequencies. As a result, the resonant frequencies to obtain a constant load voltage characteristic is theoretically derived, and thus, the voltage-source operation at the load side is achieved. The derived resonant frequencies fluctuate according to the coupling coefficient and the resistive load value. Therefore, this paper adopts a resonant frequency tracking control method to keep the load voltage constant even if the coupling coefficient and the resistive load value fluctuate. Experimental results exhibit the constant load voltage characteristic of the parallel-parallel-compensated WPT systems and agree with results of the theoretical analysis.
Preliminary design, modeling and control of a fully actuated quadrotor UAV

In this paper a preliminary study on a new concept of fully actuated Unmanned Aerial Vehicle (UAV), named ODQuad (OmniDirectional Quadrotor), is presented. By exploiting two additional actuators, the designed UAV can simultaneously modify the tilting angle of all the propellers, in such a way to decouple position and attitude motions. This solution, differently from other fully actuated UAVs with tilted propellers, avoids internal forces and energy dissipation, due to non-parallel propellers’ axes. A preliminary mechanical design and the kinematic and dynamic models are developed. Moreover, a motion control scheme, based on a hierarchical two loop, has been designed. Simulations are provided in order to show the feasibility of the concept and the effectiveness of the control scheme.
Development of an Inductorless Step-Down Converter

The objective of this paper is to propose an inductorless non-isolated step-down converter. The proposed converter is composed of multiple charging pump DC-DC converters with interleaving operation. Based on the characteristic of charging pump capacitor, the presented converter does not require an inductor and can obtain the step-down output voltage. Advantages of the proposed converter include: inductorless power conversion, control circuit simplicity, low voltage stress, low input current ripple, low output voltage ripple, and fault-tolerant operation for each DC-DC converter module. Based on the circuit analysis, the power loss can be evaluated with the capacitance of bridge capacitor and switching frequency. Also, with the interleaved operation between the charging pump converters, the current ripple of the input can be reduced without the need of input inductor. The computer simulations and hardware experimental results are shown to verify the performance of the proposed inductorless step-down converter. The peak efficiency from an input voltage 100 V, output voltage 50 V, and output power 75W prototype is around 97.2%.
Confinement of acoustic fields in a honeycomb phononic crystal slab

We demonstrate the confinement of acoustic waves in a microscopic phononic crystal slab consisting of a honeycomb array of holes in silicon. The acoustic field is measured on the sample surface at frequencies up to 1GHz by means of an ultrafast optical technique. Using temporal Fourier transforms, the confinement is shown to depend on frequency, and a phononic band gap is identified. Finite element simulations are performed and used to analyze the results.
Generalized Switched Systems with Application to Hybrid Systems

As an extension of standard switched systems, this paper presents a new formulation of generalized switched systems. Such a generalization allows switching among different types of systems. Hence a hybrid system can be treated as a special case of such generalized switched systems. With the design freedom gained from this formulation, it is possible to design an appropriate switching signal between a family of continuous-time systems and a family of discrete-time systems to achieve a better performance. This paper introduces fundamental definitions and stability results. The concept of output persistent excitation condition is proposed, which links closely to uniform global asymptotic stability. To illustrate the usefulness of this new formulation, stability results of the hybrid systems are revisited to show how this formulation works.
Miniaturized Evanescent Mode Substrate Integrated Waveguide Filter with Mixed-Coupled Folded Complementary Split-Ring Resonators

A miniaturized evanescent mode substrate integrated waveguide (SIW) bandpass filter loaded with mixed-coupled folded complementary split-ring resonators (FCSRRs) is reported in this work. Compared with the conventional CSRR, the proposed FCSRR is with enhanced product of equivalent inductance and capacitance, which is beneficial for size reduction of the conventional CSRR. Hence, as the FCSS pair are loaded into SIW, the newly-formed resonator will exhibit evanescent mode resonance characteristic as well, and even achieve smaller physical size as compared its corresponding conventional CSRR-based counterpart. Meanwhile, it has been well-known that, in the SIW section with a pair of face-to-face FCSRRs, a transmission zero (TZ) at the upper stopband can be generated by the mixed coupling between the SIW and FCSRRs. Furthermore, by adding a slot between the splits of the two FCSRRs, a dual-mode resonator is developed, in which the cross-coupling scheme is constituted to produce an extra TZ at the lower stopband of the resonator to improve its selectivity performance notably. To demonstrate the aforementioned idea, a size-miniaturized bandpass filter based on the proposed SIW section with mixed-coupled FCSRRs is realized. Experimental results show that both miniature physical size and good performance are achieved simultaneously, which illustrates that the proposed work is promising in practical radio frequency (RF) and microwave applications.
Carrier Based PWM Control of 3-Level NPC Inverter with DC Neutral Point Balancing and Common Mode Voltage Reduction

The paper presents a new Carrier based PWM method for 3-level NPC inverter to simultaneously mitigate neutral point (NP) voltage variation and to reduce common mode voltage (CMV). The proposed PWM method can be performed with double modulation waves. An offset modification helps to determine RCMV PWM patterns with zero NP current. Then, hybrid reduced CMV PWM patterns have been designed to minimize number of extra switching and to bring down line voltage stress dv/dt to a half value. Finally, various current based RCMV-PWM methods have been proposed to suppress NP voltage oscillation. The theoretical analysis will be verified by simulation and experimental results.
Overview of Development in Reconfigurable Multi-Mode Multi-Band Power Amplifier Design

Reconfigurable multi-mode multi-band power amplifier, due to its unique architecture and numerous applications, has been of great interest to both academic society and micro-wave/RF industry, especially with the rapid evolution of wireless communications. Although many attempts have been made, it still remains as a very difficult challenge to the development of the RF/microwave technologies. In this paper, an overview is provided to review the new advances in reconfigurable multi-mode multi-band power amplifiers, in terms of both new architecture and design methodology. The recent development status and trends are also presented. A few examples, represented by a series of MMMB products, are also given, which unambiguously indicates that with reconfigurable technology, the power amplifier can have wider bandwidth, better performance and lower cost. This also makes reconfigurable architecture a promising technology for future multi-mode multi-band power amplifier design.