Miracle-dz/UniFAR-FTUs huggingface dataset:
A 2-20 GHz Distributed GaN Power Amplifier Using a Novel Biasing Technique

This paper presents the design and measurement of a 2 - 20 GHz GaN MMIC power amplifier fabricated on 100 µm silicon carbide using Qorvo’s QGaN15 released process. A 2-stage, non-uniform distributed power amplifier architecture is selected to achieve high performance over a decade of bandwidth. The MMIC power amplifier is fully integrated, having on-chip DC blocking capacitors at the RF terminals and on-chip RF bias inductors while only requiring low-cost bypass capacitors at the power supply terminals. A novel technique for biasing the first stage is presented which prevents bandwidth reduction due to the cascade of multiple amplifier stages. The technique allows the output DC blocking capacitor on the first stage to be eliminated while also relaxing the requirement on the first stage drain bias inductor size. The measured PA produces 2.4 - 3.5 W of output power over the 2 - 20 GHz band with 18.4 - 36.5 % PAE. The large signal gain varies between 15.8 and 17.5 dB. This combination of output power, PAE and gain over the 2 - 20 GHz bandwidth will enable development of future high performance broadband systems.
Exploring User's Perception of Storage Management Features in Instant Messaging Applications: A Case on WhatsApp Messenger

With the rapid increase in the use of mobile devices, many users use mobile instant messaging (IM) services as a way to easily communicate and connect with friends, family members, and others. Instant messaging (IM) applications provide several services such as chatting, voice calls, video calls and multimedia sharing. They are deployed with many features that aim to improve the quality of experience (QoE) for users of such services. However, the storage usage of IM applications may negatively impact the storage space of mobile devices in an unexpected way and degrade its performance. Some IM applications, such as WhatsApp, have some features and options to manage the storage usage but they are not fully visible or effective. Thus, this paper aims to explore and understand user's perception of storage related features in IM applications. We conduct a user study by considering WhatsApp application as a case study due to its popularity among other IM applications. We present a survey of 257 WhatsApp Saudi users to determine their behavior and understanding of storage related features and to identify factors that impact the storage usage of IM applications. Our results show a significant impact of duplicate and unwanted content on the storage space of WhatsApp. The results show that 56.6% of participants misunderstood the functionality of the auto-download feature and 55% of participants were not aware of the existing of storage management features. We believe that our findings will have a potential role in making better design decisions to improve the usability of storage-related features provided in several IM applications.
RRAM-based Spiking Nonvolatile Computing-In-Memory Processing Engine with Precision-Configurable In Situ Nonlinear Activation

This work presents a hybrid CMOS-RRAM integration of spiking nonvolatile computing-in-memory (nvCIM) processing engine (PE) that includes a 64Kb RRAM macro and a novel in situ nonlinear activation (ISNA) module. We integrate the computing controller and nonlinear activation function on-chip to compute convolutional or fully-connected neural network. ISNA merges A/D conversion and activation computation by leveraging its nonlinear working region. This eliminates the need for additional circuits to realize nonlinearity and reduces area by 43.7x w.r. t. the ADC scheme. The activation precision of ISNA can be configured from 1 to 8 bits to balance throughput, accuracy and power efficiency. The measurement of 4-layer LeNet shows such optimization improves 23.1% of computing speed via compromising a 2.5% relative accuracy drop. The proposed nvCIM PE achieves 16.9 TOPS/W power efficiency and a maximum spike frequency of 99.24 MHz.
Identification of Critical Parameters Affecting the Small-Signal Stability of Converter-based Microgrids

The analysis of the small-signal stability of converter-based microgrids is well established, but the existing deterministic approaches cannot fully capture the impact of random parameters resulting from complex converter control structures and stochastic operation scenarios. Accurate assessment of the relevance of different parameters can facilitate efficient modeling, online monitoring and control design of the microgrids. In this paper, a global sensitivity analysis (GSA) framework is proposed to identify the most relevant parameters that affect the small-signal stability of converter-based microgrids. First, the systematic approach to derive the complete small-signal state-space model of the microgrid is introduced and the stability index is defined. Then, the system operating states, the control and the network parameters are chosen as input variables, and the priority ranking procedure based on GSA is explained. Next, the Levenberg-Marquardt based power flow calculation is adopted to determine the steady-state operation point. The polynomial chaos expansion and the low-rank approximation methods are introduced into the GSA to further improve computation efficiency. Finally, the proposed methodology is applied to an exemplary microgrid. The critical parameters influencing the system small-signal stability are identified, and the results are compared with those of the conventional local sensitivity analysis. The correctness and effectiveness of the proposed methodology are verified by real-time simulation results.
Linearity and RF Power Handling of Capacitive RF MEMS Switches

Linearity characteristics of capacitive tuners are an important issue for today’s cellphone market. Antenna tuners have become necessary in mobile devices due to the RF spectrum expansion in the low frequency range. Capacitive tuners connected directly to the antenna change the RF voltage/current pattern and are thus exposed to large voltage swings, especially in the isolation state (minimum capacitance). In this paper, we analyze the effects of high RF power on capacitive MEMS switches. Measurements up to 6.4W were performed in the isolation state (minimum capacitance) showing the robustness of this technology under large RF power or voltage swings. Measurements demonstrated IP3 of +125dBm for a 45MHz tone spacing and third harmonic of -136dBm at +38dm of incident power.
Tunnel-Vision on Economic Linear Propulsion?

Serious initiatives for high speed transport of vehicles/pods/capsules through evacuated tubes were presented in recent years. Most suggest magnetic levitation and linear motors of long-stator design, assuming passive pods. This paper takes a the different approach, yielding minimal energy use per distance per passenger and lowest initial cost. An active pod (short-stator) on wheels with an on-board battery, able to build up speed and regenerate effectively using an inexpensive passive track is proposed. In the stations, power is received from active track-coils to charge the on-board battery. Permanent magnet (PM) track sections enable thrust to speed-up and slow-down. A relatively small rotating induction motor on the wheels enables efficient coasting. Speeding up and slowing down with a linear motor at constant power is effective in terms of component utilization. A mere 100 W/kg (common in present commercial full electric cars) is sufficient to travel long distance at high speed on record low energy consumption (<10 Wh/km per passenger).
Design and Development of Underwater Remotely Operated Locomotion Robotic System

This paper presents design, operation and performance analysis of an Underwater Remotely Operated Vehicle (UROV) robot which acquires the input from wireless based joystick controller switch. Modified designed robot can effectively endeavor as a submarine and manage its propulsion via thrusters. Thrusters are switched by relays and controlled through PIC16F877A microcontroller. The UROV attain required depth position via wireless remote terminal. In this research, thrust for water propellers, method to increased or decreased thrust is analyzed and their adeptness with respect to speed and load are discussed. The simulation results including design and performance analysis has been done to determine the robustness of proposed robot. Resemblance between the simulated design and hardware prototype design validate the precision of proposed design of UROV. The material comparison for UROV has also discussed.
Half Mode Substrate Integrated Waveguide based Leaky Wave Antenna for Frequency Beam Scanning

This paper presents a half mode substrate integrated waveguide (HMSIW) leaky-wave antenna for bidirectional frequency beam scanning. The proposed structure supports continuous beam scanning from backward to forward direction in both front and back side. This structure consists of longitudinal slots along with inductive posts. Leaky wave antenna with only longitudinal slot does not radiate along broadside results open-stopband (OSB) problem. This happens because of impedance mismatch in broadside direction. The OSB is suppressed by introducing an additional inductive post which provides required impedance matching. The proposed HMSIW LWA is designed to scan from −38° through broadsides to 34° in both front and back side in the frequency range 10-16.5 GHz.
Adaptive Riemannian BCI for Enhanced Motor Imagery Training Protocols

Traditional methods of training a Brain-Computer Interface (BCI) on motor imagery (MI) data generally involve multiple intensive sessions. The initial sessions produce simple prompts to users, while later sessions additionally provide realtime feedback to users, allowing for human adaptation to take place. However, this protocol only permits the BCI to update between sessions, with little real-time evaluation of how the classifier has improved. To solve this problem, we propose an adaptive BCI training framework which will update the classifier in real time to provide more accurate feedback to the user on 4-class motor imagery data. This framework will require only one session to fully train a BCI to a given subject. Three variations of an adaptive Riemannian BCI were implemented and compared on data from both our own recorded datasets and the commonly used BCI Competition IV Dataset 2a. Results indicate that the fastest and least computationally expensive adaptive BCI was able to correctly classify motor imagery data at a rate 5.8% higher than when using a standard protocol with limited data. In addition it was confirmed that the adaptive BCI automatically improved its performance as more data became available.
Coaxial Periodic Leaky Wave Antenna with Narrow Beamwidth and Improved Broadside Gain

This paper presents a periodic leaky wave antenna (LWA) using a coaxial cable. Leaky mode radiation is obtained from periodic slots etched on the outer conductor of the cable. Further, a periodic impedance matching unit is used to improve radiation through broadside. The main beam scans from −19° in the backward direction to +13° in the forward direction through broadside when the operating frequency is changed from 8 GHz to 11.5 GHz. The impedance matching unit helps to improve the broadside gain by 9.3 dB. The measured broadside beam width is 6° at 9.9 GHz, with a gain of 10.26 dBi. Lateral dimension of the antenna is just 6.3 mm and can be easily integrated in a microwave system.
Effect of Strain on Quantum Capacitance of Two Dimensional Intrinsic Graphene

In this article, effect of strain on quantum capacitance of 2D intrinsic graphene has been investigated and the theoretical basis of its evolution has been formulated. The variation of quantum capacitance with applied strain has extensively been studied. It is observed that quantum capacitance not only depends on magnitude of applied strain but also depends on its direction. Under anisotropic strain field, the expression of quantum capacitance is calculated from density of states (DOS) using anisotropic dispersion energy in tight-binding approximation (TBA). This anisotropy in strain field causes accumulation of charge carriers in graphene without external bias and generates energy band gap. The strain-tunable band gap is introduced in the expression of quantum capacitance that would help to control the performance of high speed graphene devices by tuning the band gap applying anisotropic strain and would open up the possibility of designing new kind of graphene based field effect devices with very thin gate dielectric.
A New Coupled Inductor-Based High Step-Up DC-DC Converter for PV Applications

In this paper, a new high step-up cascaded DC-DC converter is presented. The first stage of the proposed converter is a buck-boost converter with a modified circuit structure. The second stage is a boost converter with coupled inductor and voltage multiplier cells. The energy stored in the leakage inductor of the coupled inductor is recycled by a passive voltage clamp to a capacitor thereby improving the efficiency. Besides, the voltage across the main switch is reduced in this structure with voltage clamp circuit. Thus, a switch with a low on resistance could be used which decreases the conduction loss. The steady-state operation of the proposed topology is analyzed and performance of the proposed converter is verified through simulation in MATLAB/SIMULINK to justify the analysis.
A Monitoring System to Support Home Health Care for the Elderly with Dementia by Detecting Going Out Activities Based on RGB-D Sensors

This paper proposes a monitoring system which can be used with health care robots. As an aging society is arriving, the interest of health care for dementia patients has been increasing. However, the problem of an aging society is that the number of care workers has been decreasing. In order to supplement this shortage, developing health care robots is a hot agenda including home health care service these days. In developing a dementia health care robot, it should be able to manage some difficulties of patients and emergency situations. Especially, the missing problem of people with developing dementia is serious because it can be directly connected to death. Thus, in this paper, we propose a monitoring system to prevent the disappearance of dementia patients in advance and, which can also support health care robots. For the implementation of this, three processing steps are included. First, a calibration method for multiple cameras is presented. In the second step, a simple image retrieval pipeline will be introduced for identifying people in a house. In the last, we will explain how to detect the situation of going out activities.
A New Printed Log Periodic Antenna using SIW Concept

A compact low profile wideband antenna is developed and discussed. Its basic geometry is derived from the circular cavity following repetitive segmentation along the quasi-magnetic wall to obtain the 16th mode geometry. Aperiodic slots have been etched out alternatively from the top metallic surface, the thickness of which has been varied in a log period fashion to obtain wideband operation from the antenna. The ground plane has been engineered for quasi-omnidirectional radiation characteristics.
Optimal Impedance Modulation and Intention Angle of Elbow Assistive Robots: Load Uncertainties and Final Velocity Effects

Rehabilitation devices are widely available in clinical centers. New studies focus on enhancing the rehabilitation device by robotics technology to Assistive As Needed (AAN) robots which exercise patients according to their muscle capacity. ANN fulfills its purpose by impedance regulation and intention angle adjustment. On the other hand, human tries to leverage the body exercise by increasing the load or practicing a specific motion like reaching a certain velocity in throwing a ball. ANN devices should tackle the uncertainty in the lifted weight or reaching certain velocity tasks by impedance regulation. Moreover, they should tightly mimic the healthy human biomechanics in case of any impedance modulation and intention angle adjustment. This paper explores the optimal impedance tuning of human’s elbow joint for two particular exercises namely: weight handling and reaching certain velocity. Intrinsic passive impedance is considered in the modeling of the human elbow. The CMC (Computed Muscle Control) of the OpenSim program is utilized to compute the total resultant torque of the dominant muscles around the elbow joint.
Compact Planar 3.5/5.5 GHz Dual Band MIMO USB Dongle Antenna for WiMAX Applications

This paper presents a compact planar 3.5 GHz/5.5 GHz dual-band multiple input multiple output (MIMO) USB dongle antenna for WiMAX applications. Each antenna element has rectangular patch radiator fed by microstrip line bend. For miniaturization of antenna elements a U-shaped slot is cut in the ground plane of each antenna element with one end open and other end short. The proposed MIMO antenna has two similar elements and for improving coupling a tapered inverted T-shaped slot is cut in between the antenna elements at the ground plane side. The MIMO antenna has achieved coupling less than −20.2 dB in lower band (3.45-3.59 GHz) and less than −21.5 dB in upper band (5.46-5.58 GHz). The measured and simulated results show good agreement in both the bands. Moreover, the proposed design is also tested for its gain, efficiency, and envelope correlation coefficient at 3.5 GHz and 5.5 GHz, which shows that the proposed dual-band MIMO USB dongle antenna is suitable for WiMAX applications.
Evidence Filter of Semantic Segmented Image From Around View Monitor in Automated Parking System

An Around View Monitor (AVM) is widely used as one of the perception sensors for automated parking systems. By applying semantic segmentation based on a deep learning approach, the AVM can detect two essential elements for automated parking systems: slot marking and obstacles. However, the perception based on the deep learning approach in the AVM has certain limitations such as occlusion of the ego-vehicle region, distortion of 3D objects, and environmental noise. We overcome the problems by proposing an evidence filter that improves the detection performance based on evidence theory and a Simultaneous Localization and Mapping (SLAM) algorithm. The proposed algorithm is composed of three parts: the semantic segmentation of the AVM image, confidence modeling based on evidence theory, and evidence SLAM. Semantic segmentation classifies the grids in the AVM image into three states: slot marking, freespace, and obstacle. The grids with these three states are modeled by a confidence model based on evidence theory. Finally, the states of the grids around the ego-vehicle are accumulated and estimated by the evidence SLAM. The proposed filter was evaluated by experiments in real parking-lot environments.
Effects of Hyper-Parameters for Deep Reinforcement Learning in Robotic Motion Mimicry: A Preliminary Study

When applying deep reinforcement learning to the motion mimicry problem between teacher and student robots, this paper reports the initial results of how various hyper-parameter configurations affect performance of learning processes and quality of generated motions. The hyperparameters considered in this study include the structure of policies such as convolutional and fully connected networks, the type of activation functions such as ReLU and hyperbolic tangent, and the number of input sequences such as one, four and eight. Under these deep neural network configurations, PPO reinforcement learning algorithm has been applied for learning. In the simulator environment, the teacher NAO robot demonstrates a target action repeatedly, and the learner NAO robot tries to learn that action. The target actions include handshaking and two-arm raising. Our experimental results show that fully connected networks outperform the convolutional counterparts both in training statistics and motion quality. For activation functions, however, we found an interesting mismatch between training and evaluation quality: for example, a configuration with higher rewards does not guarantee less motion discrepancy, which may suggest a new research direction to design better loss and reward functions for robotic motion mimicry.
A 3  25 Mbps WDM-Ro-VLC system for amateur radio applications

— Radio over visible light communications (Ro-VLC) can be a pioneering technology to provide ubiquitous radio services particularly in the radio network-permitted locations. In this work, three channels, each up-converted to a 50 MHz radio signal carrying 25 Mbps data, is transmitted over a 0.5 m visible light communications link by using the cost effective on-off key (OOK) modulation format. Three red, green and blue light emitting diodes are adopted for parallel transmission. We show simulation results, carried out using OptiSystem TM software, for the bit error rates for the proposed diffuse system for both non-return to zero and return to zero data formats.
Circularly Polarized Dual Band Stacked Patch Antenna for Satellite Navigation Applications

A novel design of right hand circularly polarized antenna for dual band navigation receivers is presented. The design employs concept of stacked patches fed through a coaxial probe. Return loss better than 15dB with a peak gain of 5.46dBic/5.3dBic and gain of −4.2dB, −4.4dB/−4.5dB, −5.01dB at ±85° is achieved at both 1.17645GHz/1.57542GHz. In addition, a detailed analysis has been carried out to study the effects of different geometrical parameters on performance of the antenna
An Automated Procedure to Evaluate Usability of eHealth Platforms In The Wild

Nowadays, one of the keys for the success of ICT technologies, in particular in the e-Health realm, is “Usability”. Self-assessment questionnaires are the most diffuse procedure for its evaluation. However, this procedure presents various limitations (e.g., subjectivity, needs of expert supervisors, etc.). In this paper, a methodology based on emotion recognition, web analytics and gaze detection is developed in order to asses usability of e-Health web platforms objectively, automatically, remotely and in the wild.
Shaping and Slotting High-Q Spherical Resonators for Suppression of Higher Order Modes

This paper proposes two methods to improve the spurious-free stopband range for high-quality-factor spherical resonators and a new family of shaped spherical resonators are presented. Geometrical shaping of the proposed resonators is realized by symmetrically squeezing a spherical cavity and further opening a rectangular slot in each squeezed area. The higher order modes of the resonator are first tuned spectrally farther away from the dominant mode by the squeezing, and then are suppressed by the slotting. X-band resonator prototypes are designed, and 3-D printed by using a metallic selective laser melting technique. Quality factors of the fabricated resonators are further improved by vibration grinding process. The experiment validates effective suppression of the first higher order mode and indicates potential applications of the proposed resonators in bandpass filters to extend the spurious-free stopband bandwidths.