Miracle-dz/UniFAR-FTUs huggingface dataset:
Robust Adaptive Beamforming for Uniform Linear Arrays With Sensor Gain and Phase Uncertainties

A robust adaptive beamforming method is proposed in this paper for uniform linear arrays with respect to sensor gain and phase uncertainties. The sensor gain and phase parameters are obtained by solving a series of linear equations that describe the specific structure of the array covariance matrix for a uniform linear array. Partly calibrated parameter constraints are required due to the rank defect of the coefficient matrix. The necessary condition to enable the partly calibrated sensors to estimate all the unknown gain and phase parameters is also deduced. Sensor noise power, and hence, interference-plus-noise covariance matrix (INCM) can then be calculated with the sensor gain and phase information. The robust adaptive beamformer is finally formed using the reconstructed INCM. In comparison with other reconstruction-based beamformers, the proposed method achieves satisfactory performance when sensor gain and phase uncertainties dominate the steering vector mismatch. The effectiveness of the proposed method is also confirmed by experimental results.
Study on Failure Simulation and Fatigue Life Prediction of BGA Solder Joint Under Random Vibration

Aiming at the problem of BGA solder joint failure under random vibration, random vibration simulation and fatigue life prediction were studied, and the results were verified by experiments. Firstly, the three-dimensional finite element model of the solder joint was established by ANSYS software. The vibration characteristics of the model were obtained by analyzing the first five modes. Then the random vibration simulation analysis was performed. It was found that the solder joint had 3 extremely vulnerable areas. After that, the fatigue life of the solder joint was estimated to be 601mins using the empirical formula and three-band technique. Finally, a random vibration test was conducted. The test results show that there are 3 failure modes in the solder joint, which are consistent with the simulation analysis results; and the fatigue lifetime of the solder joint is 697mins, which means the accuracy of the fatigue life prediction is 86.2%.
Study on the Formation of the Electric Field around Three-phase Insulators in 110kV Transmission Tower and Its Influence on Flashover Voltage

The electric field distribution around the insulator is the main influencing factor of its flashover characteristics. And the electric field distribution of the insulator is affected by the external tower structure and connecting parts. Therefore, there are differences in electric field distribution of the insulators with different tower structures. And the insulator flashover characteristics vary depending on the tower structure and the suspension position of the insulators. In order to study the effect of tower structure on the electric field distribution around the insulator and its effect on flashover voltage, based on COMSOL Multiphysics, the finite element simulations on the electric field distributions around the composite three-phase insulators suspended on the umbrella-shape the drum-shape towers were conducted in this paper. The formation of the electric field distribution around the insulator suspended in the tower and the influence of the tower structure on its electric field distribution were analyzed. In addition, the flashover characteristics test of the composite insulator in the $110\mathrm {k}\mathrm {V}$ transmission line at high altitude area was carried out. The test was under a standard lightning impulse voltage of $1.2/50\mu \mathrm {s}$. Combined with the test results, the relationship between the 50% impulse discharge voltage of the three-phase insulators suspended in the tower and the uneven coefficient of electric field is further analyzed and verified.
Grid-Based Motion Planning Using Advanced Motions for Hexapod Robots

This paper presents the motion planning framework for a hexapod, based on advanced motions, for accessing challenging spaces, namely narrow pathways and large holes, both of which are surrounded by walls. The advanced motions, wall and chimney walking, utilise environment surfaces that are perpendicular to the ground plane to support the robot motion. Such techniques have not yet been studied in the literature. The hierarchical planning framework proposed here is an extension to existing approaches which have only considered ground walking where foothold contacts are confined to the ground plane. During the pre-processing phase of the 2.5D grid map, the motion primitives employed are assessed for each cell and stacked to the graph if valid. The A* algorithm is then used to find a path to the goal position. Following that, the path is post-processed to smoothen the motions and generate a continuous path. Footholds are then selected along the path. The framework has been evaluated in simulation on the custom-designed Corin hexapod. The resulting path enables access to areas that are previously thought to be inaccessible and reduces the travelling distance compared to previous studies.
FFT Radix-2 and Radix-4 FPGA Acceleration Techniques Using HLS and HDL for Digital Communication Systems

Fast Fourier Transform (FFT) is generally implemented on reconfigurable hardware in several signal processing or digital communication applications. It can be considered the most time and resource consuming operations due to the need of complex operations. The main of this manuscript is to investigate the contribution of High Level Synthesis (HLS) techniques on the implementation of real time FFT algorithms using field programmable gate arrays (FPGAs). In particular, this study focuses on communication systems incorporating filter-based-multicarrier modulations (FBMC), a promising candidate for the 5G technology. In order to evaluate the contribution of HLS, we implemented and tested various combinations such as: 8 and 16 points radix-2 and radix-4 FFT using finite precision, HLS tools and HDL while prompting parallelization, pipelining and hardware reuse architectures.
Research of Prognostic and Health Management for Avionics System Based on Massive Data Mining

The new-generation avionics system is an electronically intensive device. Its complex system structure, multiple failure modes and complex failure mechanism make it difficult to carry out effective fault prediction and health management based on traditional methods. A prognostic and health management (PHM) based on massive data mining of avionics system is presented in this paper. Firstly, the characteristics of the new generation avionics system are analyzed from the aspects of system structure, service environment, and data source and data storage mode. Secondly, the key technologies based on mass data mining are discussed, including data preprocessing, integrated management, diagnosis and prognostic model and so on. Finally, a massive data mining platform of avionics system PHM based on private cloud is proposed. The overall framework, hardware and software structure of the platform are described in detail. The massive data mining platform of avionics system can quickly and effectively carry out data mining, and provide a verification platform for the avionics system PHM, which is of great significance to promote the integration and engineering realization of avionics system PHM.
High-Speed and Intelligent Pre-Grasp Motion by a Robotic Hand Equipped with Hierarchical Proximity Sensors

Quickness, preciseness and robustness are required in manipulation tasks of robotic hands for automation of manufacturing sites. Previous researches have found that sensing from fingertips equipped with proximity sensors is available for the requirements, because it complements blind areas of vision sensors. In this paper, we develop a novel optical proximity sensor for robot fingertips which provides two levels of proximity information with different purposes, sampling rates, information quantity and quality. The lower-level information from the sensor is for high-speed feedback control of a robotic hand, and the higher-level information is for recognizing the shape and size of an object. A prototype of the sensor with 5 × 5 matrix of photo detectors is presented, and its availability is shown through basic characteristic tests. A motion experiment using a robotic hand equipped with the prototype sensors is also conducted. The result confirms that the robotic hand can adjust the position and orientation of the fingertips to various objects and then correct the grasping form according to the object size within 1s.
A Compact Wideband Omnidirectional Circularly Polarized Antenna Using TM01 Mode With Capacitive Feeding

An omnidirectional circularly polarized antenna with compact size and wideband characteristic is presented and thoroughly investigated. The antenna consists of a shorted monopolar patch proximity-fed by a disk-loaded coaxial cable and two sets of curved branches sequentially located along the radiating edges. To achieve the compact size, the patch is excited to operate in the fundamental TM<sub>01</sub> mode and the curved branches are designed with meander-line configurations. For a wideband operation, a capacitive feeding technique is employed with an additional resonance generated by the curved branches. By properly choosing the position of the stubs, a wide low-axial-ratio performance in the azimuth plane can be realized. To verify the design concept, an antenna prototype with overall size of 0.50<italic>λ<sub>L</sub></italic> × 0.50<italic>λ<sub>L</sub></italic> × 0.08<italic>λ<sub>L</sub></italic>, where <italic>λ<sub>L</sub></italic> is the free-space wavelength at minimum operating frequency, has been fabricated and measured. The measurement shows that the antenna exhibits a wide operation bandwidth of 30% with a symmetric dipole-like pattern. The realized gain in the azimuth plane is around 0.5 dBic across this band.
An Assist-as-Needed Velocity Field Control Scheme for Rehabilitation Robots

This paper addresses the problem of assist-as-needed (AAN) control for rehabilitation robots. To achieve a motion which is not explicitly a function of time, the velocity field control is considered in this paper. The proposed new controller consists of a proportional-like feedback term and a neural network (NN) term, where the later is exploited to compensate for the dynamic uncertainties of the system. The AAN property is facilitated by means of a dead-zone function in the feedback control term and a forgetting factor in the adaptation law of NN component. The designed controller guarantees the stability of the system with a bounded control command. The performance of the proposed AAN scheme is validated through the simulation and experiment conducted on a lower-limb exoskeleton.
Multi-Layer Coverage Path Planner for Autonomous Structural Inspection of High-Rise Structures

In this paper, a novel 3D coverage path planning method, which is efficient and practical for inspection of high-rise structures such as buildings or towers, using an unmanned aerial vehicle (UAV)is presented. Our approach basically focuses on developing a model-based path planner for structural inspection with a prior map, which is opposite to a non-model based exploration. The proposed method uses a volumetric map which is made before the path planning. With the map, the whole structure is divided into several layers for efficient path planning. Firstly, in each layer, a set of the normal vectors of the center point of every voxel is calculated, and then the opposing vectors become viewpoints. Due to too many viewpoints and an overlapped inspection surface, we down-sample them with a voxel grid filter. Then, the shortest tour connecting the reduced viewpoints must be computed with the Traveling Salesman Problem (TSP)solver. Lastly, all the paths in each layer are combined to form the complete path. The results are verified using simulations with a rotary wing UAV and compared with other state-of-the-art algorithm. It is proven that our method performs much better for structural inspection with respect to computation time as well as the coverage completeness,
Emergency Message Dissemination Schemes Based on Congestion Avoidance in VANET and Vehicular FoG Computing

With the rapid growth in connected vehicles, FoG-assisted vehicular ad hoc network (VANET) is an emerging and novel field of research. For information sharing, a number of messages are exchanged in various applications, including traffic monitoring and area-specific live weather and social aspects monitoring. It is quite challenging where vehicles’ speed, direction, and density of neighbors on the move are not consistent. In this scenario, congestion avoidance is also quite challenging to avoid communication loss during busy hours or in emergency cases. This paper presents emergency message dissemination schemes that are based on congestion avoidance scenario in VANET and vehicular FoG computing. In the similar vein, FoG-assisted VANET architecture is explored that can efficiently manage the message congestion scenarios. We present a taxonomy of schemes that address message congestion avoidance. Next, we have included a discussion about comparison of congestion avoidance schemes to highlight the strengths and weaknesses. We have also identified that FoG servers help to reduce the accessibility delays and congestion as compared to directly approaching cloud for all requests in linkage with big data repositories. For the dependable applicability of FoG in VANET, we have identified a number of open research challenges.
An Extrinsic Dexterity Approach to the IROS 2018 Fan Robotic Challenge

The 2018 IROS Fan Robotic Challenge tasked participants with programming a robot to autonomously open and close a Spanish folding fan, highlighting the obstacles still associated with the dexterous manipulation of objects for robotic systems. Since high DoFs grippers are complex to coordinate and overkill for many industrial processes, our approach used an under-actuated parallel gripper with a 3D-printed adaptation to precisely grasp the fan in such a manner that gravity could be leveraged to act on the fan to produce an extrinsic, or external, dexterity. With our approach, we completed the challenge in 12.38 seconds, resulting in a top three finish. Furthermore, using a multi-modal tactile sensor, we analyzed the vibrations in the grasp during the manipulation and were able to distinguish the opening and closing of the fan from the motion of the robot with a 83% accuracy.
Optimal Similarity Measurement for Discriminant Vector Machines

similarity measurements are vital in classifier design used for pattern recognition tasks. Representative vector machines (RVMs), which assign the test example according to its nearest representative vector, can be viewed as a framework of typical classifiers such as the nearest neighbor (NN) classifiers, support vector machines (SVMs), sparse representation-based classification (SRC). This paper attempts to employ a variety of similarity measurements to observe the performance of discriminant vector machines (DVMs), which are motivated from RVMs. The experiments conducted on Yale and ORL databases show that L3 norm outperforms the traditional L2 norm. Furthermore, some other similarity measurements are summarized preliminarily. This work is not only a further study of DVMs, but also a worthy perspective to optimize other classifiers.
Design and Fabrication of a Bipedal Robot Using Serial-Parallel Hybrid Leg Mechanism

In this paper, we present the design and performance evaluation of a bipedal robot that utilizes the Hybrid Leg mechanism. It is a leg mechanism that achieves 6 DOF with a combined structure of serial and parallel mechanism. It is designed to have a light structural inertia and large workspace for agile bipedal locomotion. A new version of Hybrid Leg is fabricated with carbon fiber tubes and bearings to improve its structural rigidity and accuracy while supporting its weight. A pair of Hybrid Legs is assembled together for bipedal locomotion. In the assembly, we adopt a pelvis structure with an yaw angle offset to enlarge the feet workspace, inspired by the toe-out angle of the human feet. The workspace and range of velocity are presented in simulation and verified with hardware experiments. We also demonstrate a simple forward walking motion with the developed robot.
A CBR Model for Workload Characterization in Autonomic Database Management System

For effective workload management and performance tuning in Database Management System (DBMS) the Database Administrators (DBAs) have to deal with many issues. Workload monitoring and controlling can make the things easy for a DBA. Workload type prediction and adaptation can enable monitoring and controlling of workload that helps in DBMS performance tuning. In this study we propose a Case-Based Reasoning (CBR) model for workload type prediction that also has the ability to adapt dynamic workload behavior. To observe the accuracy, effectiveness, significance and adaptiveness of the proposed CBR model, it is compared with existing well-known machine learning approaches, such as, Support Vector Machine (SVM) and Neural Network (NN). For the validation of the proposed CBR model many standard benchmark workloads are experimented using the MySQL DBMS. The standard TPC-C and TPC-H like queries are used for generating training and testing data. In this study various experiments have been performed for Online Transaction Processing (OLTP) and Decision Support System (DSS) workloads. The proposed CBR model characterizes the workload through predicting its types. At the end, for result validation we have performed post-hoc tests which shows that the proposed CBR model produces better results.
The Power Consumption Decreasing of the Two-Wheeled Balancing Robot

This article is devoted to solving the task of decreasing the power consumption of a two-wheeled balancing robot. Since the power source of this device is on-board batteries the requirement for power consumption is relevant. In the course of the work the analysis of the device processes which shows that a significant current flows in the windings of the motors during the stabilizing system operation is carried out. This is the reason for the high power consumption. In addition this causes the motor windings heating which also has a negative effect on the system operation. Further in the work the factors influencing the power consumption of the device are researched taking into account the features of stabilization system implementation on a microcontroller and the features of the actuators and their control. Based on the result of this research a method of reducing ripple of the current in the motor windings is proposed and an example of its implementation in the control program of the device is given. It is shown that such system can be realized. And finally the results of measuring the supply current of the device which show significant reducing the power consumption are given.
Online Distributed Security Constrained Economic Dispatch for Active Distribution Networks Based on Feedback Strategy

This paper investigates the distributed security constrained economic dispatch (SCED) problem in an active distribution network, pursuing the minimization of generation cost of the entire system considering network security and generation limit constraints. A feedback strategy derived from the duality-based method is proposed to achieve the distributed solution of SCED. In the proposed strategy, the distribution management system (DMS) and microgenerators (MGs) are regarded as intelligent agents in charge of fast calculation and measurement. The variation of system demand results in fluctuations on branch flows, which can be measured by DMS and then transmitted to MGs. Each MG can adjust itself active power output independently so as to respond to system demand variation, and meanwhile ensure network security. The proposed method only requires partial dual variable information transfer from the DMS agent to MG agents, and has plug-and-play features. Simulations of the IEEE 33-bus system are provided to illustrate the performance and robustness of the proposed algorithm.
Dual-Band Dual-Sense Polarization Reconfigurable Circularly Polarized Antenna

This letter presents a novel dual-band circularly polarized slot antenna. The far-field polarization of the antenna can be switched electronically between left-hand circular polarization and right-hand circular polarization. A 50 Ω microstrip feed line is divided into four arms those excite a ground plane slot. The p-i-n diodes are introduced in the arms for polarization switching. A prototype dual-band dual-sense antenna with <italic>f</italic><sub>01</sub> = 2.4 GHz and <italic>f</italic><sub>02</sub> = 5.2 GHz is fabricated using a 1.6 mm thick FR4 substrate. The measured 3 dB axial ratio bandwidths are more than 16.6% and 5.7% at the lower and upper bands, respectively. The measured return loss is more than 10 dB over the wireless local area network (LAN) bands.
Towards Guidelines for Mental State Induction in First-Person Shooters

In this paper we develop design guidelines for mental state induction in first-person shooters (FPS). To illustrate our design guidelines, we develop four versions of a first-person shooter video game each inducing a specific mental state on the player following our guidelines. We also conduct an evaluation using the self-perceived mental state of the participants as a metric to compare the mental state induced with each version. Results show that we were able to induce frustration, suggesting that further research is needed to fully understand the relation of gameplay and mental state inducement on FPS games.
A Simulation Based Band-Pass Filter to Improve the Polynomial Chirplet Transform in Fault Detection

Bearings are the basic components in mechanical or hydraulic power transmission systems. Defects in bearings will lead to a sudden stoppage of machines. In this paper, we develop a new fault detection method based on the numerical simulation determined band-pass filter and polynomial chirplet transform (PCT). Using band-pass filter, the sub-signal containing the information of fault feature is preserved and further decomposed by PCT to obtain time-frequency spectrum with higher signal to noise ratio (SNR). To design the efficient band-pass filter, the input center frequency is predetermined by finite element simulations. To improve the performance of the traditional chirplet transform (CT), a polynomial kernel function is employed to construct one of the parameterized time-frequency analysis methods, i.e., PCT. PCT reconstructs the time-frequency spectrum along the frequency trajectory so that the energy distribution on the spectrum is concentrated around the real instantaneous frequency of the signal. Thus, the PCT generates high time-frequency resolution, which is suitable for weak fault detection. The effectiveness of the proposed method in fault diagnosis is demonstrated by applications for vibration signal collected from bearings in both mechanical and hydraulic power transmission systems.