The paper presents a methodology for social distancing detection using deep learning to evaluate the distance between people to mitigate the impact of this coronavirus pandemic. The detection tool was developed to alert people to maintain a safe distance with each other by evaluating a video feed. The video frame from the camera was used as input, and the open-source object detection pre-trained model based on the YOLOv3 algorithm was employed for pedestrian detection. Later, the video frame was transformed into top-down view for distance measurement from the 2D plane. The distance between people can be estimated and any noncompliant pair of people in the display will be indicated with a red frame and red line. The proposed method was validated on a pre-recorded video of pedestrians walking on the street. The result shows that the proposed method is able to determine the social distancing measures between multiple people in the video. The developed technique can be further developed as a detection tool in realtime application.

This paper reviewed several previous papers on work that have been done on the development of in-pipe inspection robot for the last 20 years. By sorting the types of the inspection robots they can be divided into several groups according to their locomotion. Each prototype has its own advantages and disadvantages depending on its design requirements and purpose of inspection. The prototypes have been tested in several experiments in order to verify its functionality and efficiency of inspection task. Some of the researchers ran simulations to validate the kinematic and modeling the mechanism of their own prototype. Developing in-pipe inspection robot can overcome the issues of human factor in labour intensive or dangerous work and also to act in inaccessible environment during repair and maintaining inside the pipeline.I.

Chaotic maps that can provide highly secure key sequences and ease of structure implementation are predominant requirements in image encryption systems. One Dimensional (1D) chaotic maps have the advantage of a simple structure and can be easily implemented by software and hardware. However, key sequences produced by 1D chaotic maps are not adequately secure. Therefore, to improve the 1D chaotic maps sequence security, we propose two chaotic maps: 1D Improved Logistic Map (1D-ILM) and 1D Improved Quadratic Map (1D-IQM). The proposed maps have shown higher efficiency than existing maps in terms of Lyapunov exponent, complexity, wider chaotic range, and higher sensitivity. Additionally, we present an efficient and fast encryption method based on 1D-ILM and 1D-IQM to enhance image encryption system performance. This paper also introduces a key expansion method to reduce the number of chaotic map iteration needs, thereby decreasing encryption time. The security analyses and experimental results are confirmed that 2D Correlation Coefficient (CC) Information Entropy (IE), Number of Pixels Change Rate (NPCR), Unified Average Changing Intensity (UACI), Mean Absolute Error (MAE), and decryption quality are able to meet the encryption security demands (CC = −0.00139, IE = 7.9990, NPCR = 99.6114%, UACI = 33.46952% and MAE = 85.3473). Furthermore, the proposed keyspace reaches 10240, and the encryption time is 0.025s for an image with a size of 256 × 256. The proposed system can yield efficacious security results compared to obtained results from other encryption systems.

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Abstract-Currently, most full-polarimetric synthetic aperture radar (SAR) systems adopt linear polarization (LP). On the other hand, circular polarization (CP) is also becoming popular due to its various benefits over LP. However, since CP-SAR is an emerging technique, there are not many imaging and polarimetric analysis results in the literature. As a fundamental study on CP-SAR, this paper presents the results of an investigation on the CP properties of ground-based SAR (GB-SAR) echoes from various canonical targets and a rice paddy sample. The C-band data acquired in a laboratory environment are analyzed and interpreted by means of several factors such as calibration performance, experimental verification of theoretical scattering matrices, imaging quality and accuracy of scattering decomposition results. The eigenvector-based decomposition of the coherency matrix is adopted, and the performance of CP in retrieving the targets' dominant scattering mechanisms and physical parameters is evaluated from entropy-alpha (H -ᾱ) plane and orientation angle (β) value. Results demonstrate the effectiveness of CP in interpreting and discriminating the SAR image features mainly owing to its distinct advantage of highly reliable received signal strength.

Circularly polarized synthetic aperture radar (CP-SAR) is known to be insensitive to polarization mismatch losses caused by the Faraday rotation effect and antenna misalignment. Additionally, the dual-circular polarimetric (DCP) mode has proven to have more polarimetric information than that of the corresponding mode of linear polarization, i.e., the dual-linear polarimetric (DLP) mode. Owing to these benefits, this paper investigates the feasibility of CP-SAR for rice monitoring. A ground-based CP-radar system was exploited, and C-band anechoic chamber data of a self-cultivated Japanese rice paddy were acquired from germination to ripening stages. Temporal variations of polarimetric observables derived from full-circular polarimetric (FCP) and DCP as well as synthetically generated DLP data are analyzed and assessed with regard to their effectiveness in phenology retrieval. Among different observations, the H/ᾱ plane and triangle plots obtained by three scattering components (surface, double-bounce, and volume scattering) for both the FCP and DCP modes are confirmed to have reasonable capability in discriminating the relevant intervals of rice growth.

Wideband circularly polarized antenna is required for many satellite applications. Circularly polarized (CP) Equilateral Triangular-Ring Slot (ETRS) antenna has narrow 3-dB axial ratio bandwidth (ARBW) compared to its impedance bandwidth. Two diagonal line slots were introduced to ETRS for enhancing its 3-dB ARBW. The diagonal line slots were inserted on the left and right side of ETRS. Lengths of the left and right line slots correspond to the lowest and highest frequencies of ETRS antenna 3-dB ARBW, respectively. Both diagonal line slots have successfully improved 3-dB ARBW of ETRS antenna by achieving 680 MHz or 37% fractional bandwidth. Measured results of x-z and y-z planes of radiation patterns also confirm that the antenna has bidirectional radiation and presents good CP performance within its 3-dB ARBW. ETRS antenna RHCP gain is also improved thanks to the diagonal line slots insertion.

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