Miracle-dz/UniFAR-FTUs huggingface dataset:
Design of Controllers to Track Trajectories for Multi-rotor Unmanned Aerial Vehicles

This paper presents the synthesis of controllers for a multi-rotor unmanned aerial vehicle with the goal to track trajectories, transforming its MIMO system representation into simpler structures based on SISO systems. Three control structures are provided to control the four outputs: x, y, z positions and the yaw angle. All the structures are based on decoupled control loops for each output described above. The first structure consists of classical controls, where the first two loops (x and y positions) use a third order transfer function control while the last two (z position and yaw angle) a PID/PD control. The second one uses for the first two loops a cascade control strategy based on a PD controllers. The third structure uses cascade control strategies with a PID-PID-PD-P control combination for the first two loops, while a PD-P combination for the last two. The control performance of each structure is assessed through simulation following changes of set points and a square trajectory. For a 1 [m] step change in x or y position, the system response has a setting time of around 5.7 [s, 4. 7[s], and 1.9 [s], with an overshoot of approximately 75.3%, 40.3% and 0.3% for each structure, respectively. For a 1 [m] change in z position, the setting time is 6.4 [s] and the overshoot is 24.9% for the first two structures. While for the last one, the setting time is 2.7 [s] without overshoot. Similar results are achieved for changes in the yaw angle. Finally, disturbances are included to test the robustness of the control strategies. Based on these results, the conclusion is that the third structure has the best performance.
Study on Magnetic Field Regulation of a Flux-Variable Partitioned Stator Permanent Magnet Claw Pole Motor

In order to extend the speed of permanent magnet motor (PM) by flux weakening, this paper proposes a flux-variable partitioned stator permanent magnet claw pole motor (FVPSCPM) using AlNiCo memory permanent magnet, whose magnetization level can be changed by current pulse, and NdFeB permanent magnet in series. The structure of the FVPSCPM is introduced firstly, and the principle of regulation of magnetic field is explained with the demagnetization characteristics of AlNiCo. Different combination schemes of thickness of permanent magnets are analyzed by finite element method to find out the scheme with the largest linear control range of the gap flux density. Finally, the rule of influence of permanent magnet thickness on permanent magnet working point, magnetic field regulation ability, gap flux density linear control range, no-load back EMF and rated load torque is summarized.
Reliability-Security Analysis for Harvest-to-Jam based Multi-hop LEACH Networks under Impact of Hardware Noises

This paper evaluates trade-off between reliable and secure communication for multi-hop low-energy adaptive clustering hierarchy (LEACH) networks under impact of hardware imperfection. In the proposed scheme, a source communicates with a destination via a multi-hop transmission, where the source, destination and intermediate relay nodes are cluster heads (CHs). To protect the data at each hop, harvest-to-jam and randomize-and-forward methods are employed by CHs and cooperative jammers, respectively. Each jammer which is randomly selected at each cluster harvests energy from the previous CHs to transmit noises to an eavesdropper. We derive closed-form expressions of the end-to-end outage probability (OP) and intercept probability (IP) for the proposed scheme over Rayleigh fading channels. Then, the theoretical derivations are verified by Monte-Carlo simulations.
Short Faults in Permanent Magnet Synchronous Machine with Variable Flux Hybrid Rotor

The permanent magnet synchronous machine (PMSM)with variable flux hybrid rotor(VFHR) is a hot topic in reliability-critical application like aeronautical servo/drive systems. It is of great benefits to deepen the working mechanism of the permanent magnet synchronous machine with variable flux hybrid rotor for its anti-short capacity by analyzing the transient electromagnetic performance of interturn short faults in PMSM with VFHR. In this paper, the structure of PMSM with VFHR is adopted for analyzing the electromagnetic performance, the interturn short fault in PMSM with VFHR is modelled and transient magnetic analysis of no-load interturn short fault in PMSM with VFHR is carried out based on the model proposed in section II. The demagnetizing field of the interturn short fault is analyzed by comparing the electromagnetic performance before and after the interturn short fault occurs.
PID Parameters optimization of PMSLM servo system based on Improved Differential Evolution

This paper presents an improved differential evolution algorithm to optimize the current loop PID parameters of permanent magnet synchronous linear motor servo control system. Firstly, the screening step is added before the mutation step, and the worst individual is replaced by the best one, so as to improve the level of individuals in the group and accelerate the convergence speed. Secondly, the crossover factors and mutation factors are eliminated, so the impact of manual intervention on the results of adjustment can be reduced. Finally, the simulation results verify the effectiveness of the proposed method.
A Power Management Circuit for an Impact-type Piezoelectric Micro-wind Energy Harvester

A power management circuit with a dedicated control chip for an impact-type piezoelectric micro-wind energy harvester was designed and implemented in this study. Based on the analysis of the output characteristics of impact-type piezoelectric energy harvester, a buck-boost converter is used to realize the function of alternated resistive matching impedance strategy for obtaining maximum power. The dedicated control chip integrates an oscillator with two kinds of oscillating periods, an operation mode selector module, and an overvoltage protection circuit for load battery. The simulation results of the dedicated control chip verified the circuit functions well, and the start-up voltage is as low as 1.59V, if the load battery is completely drained.
Hyperspectral Unmixing Via Wavelet Based Autoencoder Network

Hyperspectral unmixing is a hot topic in the field of remote sensing. Due to the limitation of spatial resolution and diversity of object distribution, hyperspectral image contains mixed pixels, which brings a great challenge for hyperspectral image processing. A novel wavelet based hyperspectral unmixing autoencoder network is proposed in this paper. In the framework of autoencoder network, multiscale wavelet coefficients of the signal are employed, which contribute to learn the intrinsic feature of endmember deeply. Moreover, the cost function of the network is designed according to the sparsity and nonnegative constraints of abundance, as well as the spectral fidelity. Experimental results on both simulated and real hyperspectral data sets demonstrate that the proposed method outperforms other state-of-the-art unmixing methods.
Influences of 3D fluid field for submersible permanent magnet motors on thermal field distribution

Temperature field research is crucial for the stable operation of submersible motors. The paper considers the influence of rotating magnetic field and harmonic magnetic field, analyzes the distribution of iron loss density in different stator regions, and uses the spatial distribution loss loading method to couple the calculation model temperature field. Given the boundary conditions and basic assumptions of the moving region and the stationary region in the flow field space, the finite volume method is used to solve the fluid motion equation and the energy equation, the motion state of the fluid medium in the flow field and the heat dissipation coefficient of each surface inside and outside the motor can be obtained. Based on this, calculation of the three-dimensional global temperature field of the motor, analyze the influence of fluid velocity on the motor's temperature rise according to the steady-state operating temperature distribution result, and provide reference for the selection scheme of the liquid flow rate limitation. Ensure the safe operation of the submersible motor under high temperature environment.
A Negative-Bias-Temperature-Instability Study on Omega-Gate Silicon Nanowire SOI pMOSFETs

The Negative-Bias-Temperature-Instability (NBTI) is an important reliability parameter for advanced technology nodes. This work presents an experimental study of NBTI in omega-gate nanowire (NW) pMOSFET. The 3D-numerical simulations were performed in order to better understand the NBTI effect in NW transistors. The results shows that NBTI in NW is high ($\Delta$ V $\approx200 -300$mV – for W = 10nm) due to the higher gate oxide electric field accelerating the NBTI effect providing a higher degradation. This study was performed for different channel widths and lengths.
LYRA: an Interactive and Interactive Storyteller

Storytelling has always been a crucial part of education and caring of children throughout human history. Even in modern ages with advanced digital technologies and multimedia contents, the educational impact of storytelling for children is still very important. However, modern parents have less time for reading books for their children. The development of audiobooks and automatic speech recognition technology enabled a type of automatic storytelling without the burden of parents. However, the educational and psychological benefits of storytelling are not only in passive listening but also in an interactive exchange of interchanging questions and answers regarding the story. In this paper, I developed a prototype system of interactive storytelling utilizing encoder-decoder style neural network dialog system. I conducted a user study with the system and found out that the interactive dialog is useful for better understanding and satisfaction of users. I suggested another program involving dynamic narrative storytelling. With this feature, the answers given by children can change the storyline in logical and natural manner so that the children can build their decision making and communication capabilities. I believe that children's education could be vastly improved by applying artificial intelligence to storytelling, as studied and demonstrated in this paper.
Alpha-DBL: A Reasonable High Secure Double-Block-Length Hash Function

We propose a new double-block-length compression function which is called Alpha-DBL. This scheme using two parallel secure single block length schemes based on a block cipher with 2n-bits key and n-bits block size to compress a 3n-bits string to a 2n-bits one. We show that Alpha-DBL scheme attains nearly optimal collision security and preimage security bounds (up to 2n and 22n queries for finding a collision and a preimage, respectively). More precisely, for n=128 no adversary making less than 2n−1.27= 2126.73 queries can find a collision with probability greater than 1/2. With our knowledge, this collision security bound is better than other of such a compression function. In addition, we give a preimage security analysis of Alpha-DBL that show security bound of 22n−5 = 2251 queries for n=128. Using this scheme in the iterated hash function construction can preserve the collision resistance security and the preimage resistance security.
Lightweight Stream Cipher Scheme for Resource-Constrained IoT Devices

The Internet of Things (IoT) systems are vulnerable to many security threats that may have drastic impacts. Existing cryptographic solutions do not cater for the limitations of resource-constrained IoT devices, nor for real-time requirements of some IoT applications. Therefore, it is essential to design new efficient cipher schemes with low overhead in terms of delay and resource requirements. In this paper, we propose a lightweight stream cipher scheme, which is based, on one hand, on the dynamic key-dependent approach to achieve a high security level, and on the other hand, the scheme involves few simple operations to minimize the overhead. In our approach, cryptographic primitives change in a dynamic lightweight manner for each input block. Security and performance study as well as experimentation are performed to validate that the proposed cipher achieves a high level of efficiency and robustness, making it suitable for resource-constrained IoT devices.
Sensor Fault Diagnosis of Multi-Zone HVAC Systems Using Auto-Associative Neural Network

This paper presents a data-driven sensor fault diagnosis algorithm for multi-zone Heating, Ventilation, and Air conditioning (HVAC) systems based on an Auto-Associative Neural Networks (AANNs) framework. The proposed method can be used for both single and multiple sensor faults diagnosis by comparing the input of the network with the output and then identifying and isolating the fault based on the generated residuals. The implementation of the proposed method and the evaluation results are presented and demonstrated thoroughly in the paper for a simple 2-zone HVAC system using the transient systems simulation program (TRNSYS) considering single and multiple bias and drift sensor faults. The performance of the AANN-based approach is compared with a Principle Component Analysis (PCA)-based method and the results show a significant improvement in terms of the diagnosis accuracy.
Kraken-Mobile: Cross-Device Interaction-Based Testing of Android Apps

Mobile applications that involve the interaction of two or more users are becoming more common nowadays, and the demand of good performance and availability by their users is increasing. This makes testing and automation of processes essential for delivering high-quality cross-device apps. In this paper, we present Kraken, a cross-device testing tool that enables a tester to write, run, and validate test scenarios that involve the interaction of more than two devices as well as its underlying implementation. The proposed tool uses APKs as input along with tests scripts wrote using the Gherkin syntax. Kraken is publicly available on GitHub https://thesoftwaredesignlab.github. io/KrakenMobile/ Videos: https://www.youtube. com/playlist? list=PLF5U8kfVgRcJ3RCHt7cWmwlqN93brbVW-
A Calculation Method of Asymmetric Faults Current in Three-Phase Four-Wire Synchronverter

Three-phase four-wire virtual synchronous generator (TPFW-VSG) provides a zero-sequence current path by introducing a neutral line. However, it will generate an inrush current under asymmetric faults, which will damage the power electronic devices. Therefore, it is of great value to analyze TPFW-VSG’s fault current characteristics. In this paper, the calculation method of instantaneous inrush current of TPFW-VSG under asymmetric faults is proposed by simplifying equivalent models, and the main influencing factors of asymmetric faults current are analyzed. The analysis shows that the fault current is mainly composed of the periodic component and the free component. Moreover, the main influencing factors include control loop and asymmetric faults type. Finally, PSCAD simulation and MATLAB calculation results verify the correctness of the above analysis.
Turn-off Period Improved Switching Model of SiC Devices with Stray Capacitances and Inductances

In order to analyze the switching behavior of SiC devices, this paper presents an improved switching model which considered the parasitic inductance, the nonlinear capacitances and the nonlinear transfer characteristic of SiC devices. Besides, this paper presents a new sub-period during turn-off transient when current is small. The proposed model is expressed by differential equations and the result can be obtained by iterative solution. The experiment is carried out based SiC bare dies at 400V DC voltage, 10A and 40A current. The result shows that the improved model matches the experiment better than the referenced model. At 40A condition, the relative error of turnoff losses are decreased by 53.8%, and the relative error of turn-on losses are decreased by 15.6% by using the proposed model. At 10A condition, the relative error of turn-off losses is decreased by 67%.
An Industrial Study on the Differences between Pre-Release and Post-Release Bugs

Software bugs constitute a frequent and common issue of software development. To deal with this problem, modern software development methodologies introduce dedicated quality assurance procedures. At the same time researchers aim at developing techniques capable of supporting the early discovery and fix of bugs. One important factor that guides such research attempts is the characteristics of software bugs and bug fixes. In this paper, we present an industrial study on the characteristics and differences between pre-release bugs, i.e. bugs detected during software development, and post-release bugs, i.e. bugs that escaped to production. Understanding such differences is of paramount importance as it will improve our understanding on the testing and debugging support that practitioners require from the research community, on the validity of the assumptions of several research techniques, and, most importantly, on the reasons why bugs escape to production. To this end, we analyze 37 industrial projects from BGL BNP Paribas and document the differences between pre-release bugs and post-release bugs. Our findings suggest that post-release bugs are more complex to fix, requiring developers to modify several source code files, written in different programming languages, and configuration files, as well. We also find that approximately 82% of the post-release bugs involve code additions and can be characterized as 'omission' bugs. Finally, we conclude the paper with a discussion on the implications of our study and provide guidance to future research directions.
A Diagnosis Strategy for High-Frequency Link Bidirectional AC-DC Matrix Converter

In order to enhance the stability of high-frequency link bidirectional AC-DC matrix converter (HFLMC) during system execution, a fault diagnosis strategy is proposed to identify open-circuit fault of power devices in this paper. Firstly, detailed electrical waveform analysis to summarize the output voltage fault characteristics of the converter under normal and failure situations are shown. Based on this analysis, a fault diagnosis strategy is proposed which can identify the fault location either in an IGBT or in a diode in the H-bridge converter (HBC). In addition, the faulty bidirectional switch of three-phase to single-phase matrix converter (3-1MC) is detected by the switch group error voltage in different switching states. The proposed method has the advantages of accurate diagnosis and simple implementation. Finally, the simulation results testify the accuracy of the theoretical analysis and the feasibility of the proposed fault diagnosis strategy.
Research on simulation technology of megawatt wind turbine based on three-phase asynchronous motor

Wind turbine simulation technology provides laboratory verification and exploration conditions for wind power system research. In response to the problem that it is difficult for small power motors in the laboratory to accurately simulate the characteristics of megawatt wind turbines. Within the range of actual wind turbine power that small power three-phase asynchronous motor can simulate, a virtual proportional wind turbine model corresponding to the actual megawatt wind turbines is established by using the similarity theory and normalized consistency. The steady-state and dynamic characteristics of megawatt wind turbines are simulated by using the strategy of rotational inertia compensation with shaft torque feedback. A wind turbine simulation system is developed, which is monitored by the upper computer and drives three-phase asynchronous motors by two groups of inverters to simulate wind turbines and wind turbines load respectively. The structure of the system is simple and easy to implement. The experimental results show that the simulation technology and the designed experimental system can simulate the characteristics of megawatt wind turbines reasonably and accurately.
Development of a Smart Seat Cushion for Heart Rate Monitoring Using Ballistocardiography

For many individuals with cardiac conditions, long term monitoring of heart vitals is an essential part of ongoing care. Current monitoring technologies, such as wearables and medical devices, though accurate, are obtrusive, require the person to remember to use them, and need to be used correctly. Wearable monitors are, therefore, not ideal for everyone. This research developed a prototype portable seat cushion that can capture heart rate using a cardiovascular signal called the ballistocardiogram (BCG) by a person simply sitting on the cushion. The cushion uses load cells embedded inside it as well as analog and digital signal conditioning to obtain BCG, which is then processed to calculate heart rate. Results from nine participants sitting still show that the cushion is able to obtain an average accuracy of 95.1%, which is as good as or better than other similar methods reported in the literature. To the authors' knowledge, this work represents the first portable ambient device for measuring heart rate from a seated position. The smart seat cushion can easily be integrated into an Ambient Assisted Living (AAL) system and offers a zero-effort and unobtrusive alternative to wearable monitoring devices.
Angular Measurements and Analysis of the Indoor Propagation Channel at 60 GHz

In this work, we present a propagation measurements campaign conducted at 60 GHz in a typical indoor office environment. These measurements can be useful in order to exploit multipaths, aiming to maintain the quality of the communication in the case of blocking the direct path due to an obstruction created by people, furniture or other obstacles. The measurements were realized on 2 GHz bandwidth using a vector network analyzer (VNA). At the receiving side being always visible by the transmitter, a rotation by 6° over 360° is performed. The obtained results allow to compute different channel parameters such as: path loss, RMS delay spread and coherence bandwidth. In our study, we consider for each receiver position two situations: the direct orientation and the best indirect orientation of the receiving antenna. These results show that the path loss of the best indirect orientation increases up to 18 dB compared to the direct orientation. Indeed, some positions may be more affected than others in the case of blocking the direct orientation. The obtained results will be useful both to design the new broadband communication systems and to deploy wireless local and personal area networks (WLAN/WPAN) operating in the millimeter-wave (mmWave) bands.
Switching Control with Time Optimal Sliding Mode Control Strategy for Electric Load Simulator with Backlash

Electric load simulator (ELS) plays a vital role in the ground test and simulation of the electromechanical actuator (EMA) of an unmanned aerial vehicle (UAV), which is preferred by researchers for its dynamic response and high precision. However, clearance is an inevitable problem of the ELS system which can introduce backlash influencing the stability of the system. The backlash nonlinear can induce mechanical impact and impose limitations on the quality of loading torque control. In order to increase the accuracy of loading torque, a switching control method is presented to compensate for the backlash nonlinear. A time-optimal sliding mode control (TOSMC) method is used when the ELS system entering backlash, and a nonlinear proportional integral derivative (PID) controller is presented for the different system dynamic. A switching controller is also introduced to acquire suitable moment switching from TOSMC to nonlinear PID controller, ensuring the stability of the system. Experimental tests show that compared with the traditional PID control, this method can effectively reduce the torque overshoot when ELS crossing backlash and guarantee torque tracking speed and precision of ELS.