Miracle-dz/UniFAR-FTUs huggingface dataset:
A terahertz frequency selective surface band-pass filter

This paper describes a terahertz filter based on frequency selective surface with periodic Jerusalem cross slot cell. The filter is a two-stage band-pass filter fabricated with double-side Au film and the central frequency is 220GHz. The electromagnetic modeling, simulation and analysis of the bandpass filter are presented. The influence of the dimension of the Jerusalem cross cell on the transmission characteristics of the band-pass filter is discussed. By optimizing the dimension of the Jerusalem cross cell, the band-pass filter shows that the insertion loss is −1.9dB∼ −1.6dB with a 3dB bandwidth of 8GHz, and the return loss is less than −8.9dB.
Pixel Optimizations and Digital Calibration Methods of a CMOS Image Sensor Targeting High Linearity

In this paper, different methodologies are employed to improve the linearity performance of a prototype CMOS image sensor (CIS). First, several pixel structures, including a novel pixel design based on a capacitive trans-impedance amplifier (CTIA), are proposed to achieve a higher pixel-level linearity. Furthermore, three types of digital linearity calibration methods are explored. A prototype image sensor designed in 0.18-<inline-formula> <tex-math notation="LaTeX">$\mu \text{m}$ </tex-math></inline-formula>, 1-poly, and 4-metal CIS technology with a pixel array of <inline-formula> <tex-math notation="LaTeX">$128 \times 160$ </tex-math></inline-formula> is used to verify these linearity improvement techniques. The measurement results show that the proposed CTIA pixel has the best linearity result out of all pixel structures. Meanwhile, the proposed calibration methods further improved the linearity of the CIS without changing the pixel structure. The pixel mode method achieves the most significant improvement on the linearity. One type of 4T pixel attains a nonlinearity of 0.028% with pixel mode calibration, which is two times better than the state of the art. Voltage mode (VM) and current mode (CM) calibration methods get rid of the limitation on the illumination condition during calibration operation; especially, CM calibration can further suppress the nonlinearity caused by the integration capacitor <inline-formula> <tex-math notation="LaTeX">$C_{\textit {FD}}$ </tex-math></inline-formula> on the floating diffusion node, which is remnant in VM.
The Indoor Positioning Fusion Algorithm of Multi-source and Heterogeneous

In order to meet the needs of complex indoor environment, it is important to develop more efficient solution to solve the problem of indoor positioning accuracy. In this paper, an indoor fusion positioning scheme is proposed, which uses Bluetooth, WIFI and ultra-wideband positioning for fusion and collaboration strategy, and uses the strategy of Heterogeneous network data fusion and the algorithm of similarity match to provide multi-source fusion indoor positioning. To evaluate our method, the experiments base of the Guilin Smart Industrial Park Incubation Center are achieved. The experiment results show that the indoor fusion positioning effect is greatly improved compared with the single positioning method, and the positioning error is significantly reduced.
Classification of Retinal Diseases from OCT scans using Convolutional Neural Networks

Biomedical image classification for diseases is a lengthy and manual process. However recent progresses in computer vision has enabled detection and classification of medical images using machine intelligence a more feasible solution. We explore the possibility of automated detection and classification of retinal abnormalities from retinal OCT scan images of patients. We develop an algorithm to detect the region of interest from a retinal OCT scan and use a computationally inexpensive single layer convolutional neutral network structure for the classification process. Our model is trained on an open source retinal OCT dataset containing 83,484 images of various tunnel disease patients and provides a feasible classification accuracy.
Study on Connection Boundary Conditions in Ionospheric Plasma Dispersive Media

In this paper, a method for studying the boundary conditions in ionospheric plasma dispersive media is proposed. Firstly, the Huygens principle is introduced briefly. Then the Huygens principle is introduced according to the incident source of FDTD algorithm. Finally, the boundary conditions of the plasma are modified, and the Drude model is selected to describe the dispersion characteristics of the plasma and numerical simulation. The simulation results show that the coherent error of the total field is the leakage of the scattered field, and it is verified that the modified connection boundary is correct.
Stability Analysis for the Grid-Connected Single-Phase Asymmetrical Cascaded Multilevel Inverter With SRF-PI Current Control Under Weak Grid Conditions

This paper analyzes the influence of phase-locked loop (PLL) on the stability of LCL-type single-phase grid-connected asymmetrical cascaded H-bridge multilevel inverter (ACHMI) with synchronous reference frame proportional-integral (SRF-PI) grid current control under weak grid scenarios. The ACHMI system is composed of power stage circuit and control system, where the control system contains the dual-loop current control strategy established in the hybrid reference frame, the SRF-PLL, and the hybrid modulation method employed to synthesize the multilevel output voltage. The small-signal model of the whole ACHMI system is first established by using a simple step-by-step derivation method, and then, the small-signal analysis method is adopted to linearize the ACHMI, which is then utilized to derive the impedance model of the ACHMI system. Furthermore, an improved impedance stability criterion is derived, which is then employed to analyze the system stability. By using this criterion, the stability of the ACHMI can be evaluated with the variation of the bandwidth of PLL, the output power factor angle of the ACHMI, and the amplitude of the grid current reference signal under weak grid conditions. In this paper, a systematic design procedure for the optimal selection of the PI controller of the PLL is presented, which guarantees the steady-state performance and dynamic response of the ACHMI system. With this design method, the dual-loop current control and PLL can be taken into account simultaneously when analyzing the stability margin of the ACHMI. Finally, the simulation and experimental results from a down-scaled grid-connected ACHMI prototype system are provided to confirm the validity of theoretical analysis.
Detection of LDDoS Attacks Based on TCP Connection Parameters

Low-rate application layer distributed denial of service (LDDoS) attacks are both powerful and stealthy. They force vulnerable webservers to open all available connections to the adversary, denying resources to real users. Mitigation advice focuses on solutions that potentially degrade quality of service for legitimate connections. Furthermore, without accurate detection mechanisms, distributed attacks can bypass these defences. A methodology for detection of LDDoS attacks, based on characteristics of malicious TCP flows, is proposed within this paper. Research will be conducted using combinations of two datasets: one generated from a simulated network, the other from the publically available CIC DoS dataset. Both contain the attacks slowread, slowheaders and slowbody, alongside legitimate web browsing. TCP flow features are extracted from all connections. Experimentation was carried out using six supervised AI algorithms to categorise attack from legitimate flows. Decision trees and kNN accurately classified up to 99.99% of flows, with exceptionally low false positive and false negative rates, demonstrating the potential of AI in LDDoS detection.
A Survey on Game Analytics in Massive Multiplayer Online Games

Massive Multiplayer Online games (MMOG or MMO games) can gather hundreds, thousands or even millions of players. They build persistent world games where social relationships are established to improve the performance of the users and their online, centralized and persistent nature facilitates the collection and analysis of user data. Since keeping players engagement is very important to the MMOG business model, the adoption of Game Analytics to better understand the player experience became widespread among game developers and researchers. This paper makes a survey of articles published over the last fourteen years that apply Game Analytics techniques on Massive Multiplayer Online Games. The objective is to outline the recent research conducted in this area: the type of MMOG that is the object of research; the most common game metrics adopted; the game telemetry used in the research. For this, 31 papers were selected from IEEE and ACM Digital Libraries and analyzed. Such selection was done by searching the keywords Massive Multiplayer Games on both libraries and Game Analytics on the ACM library. Many tendencies were found upon selecting and analyzing each paper. Such as World of Warcraft being the most researched game, while RPG was the most researched sub-genre. Other observations include that the improvement of the game was the aim of about one-third of the sample and the most common data source was the Game Log from each game.
A Single-Inductor Dual-Output Converter With the Stacked mosfet Driving Technique for Low Quiescent Current and Cross Regulation

Stacked mosfet structures made of low-voltage devices suffer from degraded transient response or large footprint when a capacitorless or dominant-pole compensated low-dropout (LDO) regulator biases the driver. Due to the self-stabilizing nature, the proposed stacked mosfet driver (SMD) technology effectively drives the power stage and greatly reduces the noise at the switching nodes for low cross regulation (CR) in a single-inductor dual-output (SIDO) converter. In addition, two inherent LDO regulators in SMD technology fully regulate the dual outputs with the advantage of low quiescent current at no-load conditions. The experimental results show that the test chip fabricated under the 0.25-μm process has low CR of 0.015 mV/mA and ultralow quiescent current of 5 μA under no-load conditions.
Fast Pedestrian Detection in Surveillance Video Based on Soft Target Training of Shallow Random Forest

In recent years, deep learning algorithms have achieved top performances in object detection tasks. However, in real-time, systems having memory or computing limitations very wide and deep networks with numerous parameters constitute a major obstacle. In this paper, we propose a fast method for detecting pedestrians in surveillance systems having limited memory and processing units. Our proposed method applies a model compression technique based on a teacher–student framework to a random forest (RF) classifier instead of a wide and deep network because a compressed deep network still demands a large memory for a large amount of parameters and processing resources for multiplication. The first objective of the proposed compression method is to train a student shallow RF (S-RF), which can mimic the teacher RF’s performance, by using a softened version of the teacher RF’s output. Second, a deep network cannot easily detect small and closely located pedestrians in a surveillance video captured from a high perspective because of frequent convolutions and pooling processes. In this paper, adaptive image scaling and region of interest with S-RF were therefore combined to allow fast and accurate pedestrian detection in a low-specification surveillance system. In experiments, our proposed method achieved up to a 2.2 times faster speed and a 2.68 times higher compression rate than teacher RF and a better detection performance than several state-of-the-art methods on the Performance Evaluation of Tracking and Surveillance 2006, Town Centre, and Caltech benchmark datasets.
Domain Knowledge Driven Deep Unrolling for Rain Removal from Single Image

Rain is a common weather that seriously affects the performance of outdoor computer vision applications. The quality of images taken in such weather is very poor. There are several popular methods for the removal of rain streaks from images; one such method is based on physical models and mathematical optimization, and another method is based on deep-learning. However, these methods have their own shortcomings. The optimization-based method is complex, but the result is general. In the deep-learning-based method, some details of the background images are lost through a deep network. In this study, we developed a ResNet and denoising algorithm embedded in the ADMM framework as the background/rain prior. ResNet was trained using synthetic rainy/clear background image pairs as the training data. Then, we divided the images taken in rainy weather into parts with a rainless background and those with the rain streaks. The experiments revealed that the PSNR value of the derain results obtained using a combination of a residual network and the ADMM algorithm was approximately 3% higher than that of the other rain-streak removal algorithms. Moreover, the detailed images obtained were considerably clearer than the details obtained from other rain-streak removal algorithms, and the image quality was better.
A Differentially Fed Dual-Polarized Magnetic Dipole Antenna for Spaceborne Applications

This paper presents a novel differentially fed dual-polarized magnetic dipole antenna with stable radiation pattern, platform independence, wide bandwidth, and robust structure for spaceborne applications. The proposed antenna is formed by a dual-polarized magnetic dipole backed by a specially designed rectangular cavity. The magnetic dipole consists of two perpendicular parallel-plate waveguides with stepped edges to broaden the impedance bandwidth, providing good structural reliability which is critical to spaceborne antennas. A cross-shaped conductor fed by two pairs of capacity coupling feeding probes is utilized to drive the dual-polarized magnetic dipole antenna. The specially designed rectangular cavity has four metal plates in four corners to shape the radiation pattern at E- and H-planes. Furthermore, thanks to the cavity, the size of the conducting platform that the antenna mounted on has limited impact on antenna’s electrical performances, particularly the radiation pattern. A prototype is fabricated and tested. Measured results show that the antenna achieves a fractional bandwidth of 18.5% with −10 dB reflection coefficient. The realized gain is about 8.5 dBi. A stable radiation pattern with a 3 dB beamwidth of 70° ± 3° and −4 dBi maximum beamwidth of 152° is observed. The measured cross-polarization is lower than −20 dB within °65°. Measured results are in good agreement with simulation ones.
Bandwidth- and Gain-Enhanced Vivaldi Antenna Array Fed by Non-uniform T-junction Power Divider for Radio Astronomy Application

A broadband Vivaldi antenna array with good radiation characteristics for radio astronomy applications is presented in this letter. To achieve a good broadband matching, a non-uniform T-junction power divider (NTPD) is adopted to design the multi-port feeding network of antenna array. Thus, the S11 of the proposed NTPD is improved from −5 to −20 dB and its impedance bandwidth is extended from 5.5 GHz to 6 GHz. Meanwhile, the proposed array presents a gain enhancement with 1dB in the low frequency band (1–3 GHz) and 2 dB in the high frequency band (3–6 GHz) with regard to the original array. To verify the design, the proposed Vivaldi antenna array has been fabricated and measured. Its input impedance, return loss, antenna gain and radiation pattern are studied. The realized gain of the Vivaldi antenna array is 5.7-11.3 dB from 1 to 6 GHz. Finally, a reasonable agreement between the measured and simulated results is observed.
Swarm Aggregation Without Communication and Global Positioning

In this letter, we propose a novel decentralized controller for the aggregation of a swarm of unicycle agents in the absence of communication and exchange of global positions. The methodology implicitly facilitates tasks like obstacle avoidance and path-following, whereas the agents exercise local decision-making. The primary aim of this letter is to form stable aggregates of a swarm using only local sensing and no inter-agent communication. A theoretical analysis of the proposed algorithm is presented based on the theory of switched systems, establishing asymptotic stability of the formed aggregates. Simulation experiments are presented to show the stability of aggregates in the presence of large, extended obstacles and external disturbances. Furthermore, we demonstrate an implementation of the proposed controller on a real system using experiments on a swarm of differential drive microbots. The proposed technique without communication demonstrates similar performance when compared with existing swarm aggregation techniques using global and local communications.
A Compact Metasurface-Enabled Dual-Band Dual-Circularly Polarized Antenna Loaded With Complementary Split Ring Resonators

In this paper, the design and experimental validation of a novel miniaturized dual-band dual-circularly polarized (CP) metasurface (MS) antenna is reported. The proposed antenna is enabled by an engineered MS-based artificial ground that supports simultaneous dual-band functionality and dual-CP unidirectional radiation. The artificial ground is a highly truncated dual-layer MS containing an array of <inline-formula> <tex-math notation="LaTeX">$2 \times 2$ </tex-math></inline-formula> unit cells. Each unit cell is comprised by a patch and a complementary split ring resonator (CSRR) printed on the top and bottom surfaces of the substrate, respectively. A printed feeding monopole antenna is integrated with the MS to form a low-profile dual-band dual-CP antenna with a thickness of <inline-formula> <tex-math notation="LaTeX">$0.04{\lambda }_{0}$ </tex-math></inline-formula>, where <inline-formula> <tex-math notation="LaTeX">${\lambda }_{0}$ </tex-math></inline-formula> is the free-space wavelength at the first operational band. A dispersion analysis of the unit cell is carried out both analytically and numerically to illustrate the working principle of the proposed antenna. This reveals that the bianisotropic response and the orientation of the CSRRs jointly provide distinct dispersion behavior along two orthogonal directions of the dual-layer MS, enabling the desired dual-band dual-CP radiation. Moreover, the CSRRs also facilitate antenna miniaturization, yielding an overall footprint of only <inline-formula> <tex-math notation="LaTeX">$0.33 \lambda _{0}\times 0.33\lambda _{0}$ </tex-math></inline-formula>. In order to verify the antenna design, a prototype is fabricated and tested, and strong agreement between simulated and measured results is observed, experimentally achieving a 50 MHz bandwidth, and a peak gain of 3.95 and 5.29 dBi at the two targeted bands with opposite handedness for the radiated waves.
Traps effect on the I-V-T characteristics of Au/n-InP Schottky barrier diode

In the present study, the I-V characteristic of Au/n-InP Schottky barrier diode (SBD) was simulated in the temperature range 200–300 K using the numerical simulator Atlas-Silvaco. By taking in to account the appropriate physical models and the presence of deep traps in the quasi-neutral region, the simulation was performed in goal to understand the effect of traps on the series resistance and the I-V curves intersection point. The obtained results clarified that the series resistance is related to the traps depth in the quasi-neutral region. In addition, the results prove that the I-V curves intersection point shift toward higher bias with increasing the series resistance value. Also the I-V curves crossing point found to be temperature dependent when the series resistance is not zero.
Computation of Feedback Capacity of Single User Multi-Antenna Stationary Gaussian Channel

In this paper, we consider the single user communications through multiple transmitting and receiving antennas over the additive stationary Gaussian channel under input power constraints. We consider the problem of finding the feedback capacity of the aforementioned channel by utilizing the control theoretic interpretation of feedback communications. We connect the problem of finding the strictly causal filter to achieve the feedback capacity with the problem of finding stabilizing feedback controllers with maximum reliable transmission rate over Youla parameters. We then evaluate the asymptotic capacity achieving upper bounds by solving finite dimensional dual optimization problem. Optimal filter obtained from dual problem is then used to derive the sequence of lower bounds. Numerical example shows that the sequence of lower bounds and upper bounds are capacity achieving.
Effect of film thickness on the structural and optical properties of SnO 2 thin films prepared by ultrasonic spray pyrolysis

In this context, we have deposited using spray prolysis technique on cleaned glass substrates a thin SnO2 layers using different deposition times from 3 min to 9 min and tin chloride was used as starting solution with a molarity of 0.1 mol/l at temperature equal 350 °C. The main results of the deposition time effect on the structural and optical properties are: Structural analysis of SnO2 film deposited at low deposition time revealed the presence of SnO phase. Moreover, increasing the deposition time, we noted the formation of the SnO2 orientation phase (111) with the absence of the SnO phase. The obtained films show good optical propertiest with an average transparency value greater than 60% in the visible region and the gap values varies between 3.98 to 3.5 eV.
Center-Fed Shorting-Via-Loaded Circular Patch Antenna with Reconfigurable Polarization and Switchable Beam

Combined polarization- and pattern-reconfigurable antenna is highly desired for future wireless systems that require high data rate and multiple functionalities. Parasitic strips are loaded around a multi-linear polarization reconfigurable antenna to obtain switchable beam for a specific polarization state. It it verified through the simulation that the main beam can be scanned to −30°, 0°, and +24° at $\phi=90^{\circ}$ polarization state by switching the PIN diodes on the parasitic strips. Furthermore, the realized gains are stable for these states, i.e., varied between 5.4 dBi and 6.5 dBi.
A platform for wireless maritime networking experimentation

We present a software platform for performing wireless maritime networking experiments, with the aim of paving the way for the deployment of IoT applications that support the coast guard in its two main roles, i.e., border surveillance and search and rescue. The platform brings together, on one hand, a novel middleware application, called Dedalus, used for monitoring and controlling experiments, and, on the other hand, a number of implementations of popular protocols that perform ad hoc routing, delay-tolerant routing, information-centric networking, and encryption. The platform has been designed in a modular manner that enhances its scalability and adaptability by the wider research community. We also present preliminary experimental results that shed light on the properties of the wireless channel and the behavior of ad hoc routing protocols in uncluttered settings.