A Computer Controlled Phase and Magnitude Self-Calibration Methodology for Phased Array Antennas

A circuit-based calibration system is presented for active phased arrays. In particular, to achieve the desired (and corrected) consecutive phase differences and relative magnitudes between RF channels, a computer controlled circuit system was developed for dynamic adjustment. The proof-of-concept demonstrator uses a phase sensor, phase shifters (PSs), and variable gain amplifiers, along with other active hardware, to realize a self-calibrating circuit system which achieves the required magnitude and phase for each array element. In addition, measured magnitude and phase imbalances are less than 0.10 dB and 3 ∘ , respectively. The computer-controlled feed network is then used to demonstrate that the system can automatically calibrate an active antenna array for various beam steering examples. Also, the S-band feed system can self-calibrate due to any monitored magnitude and phase drifts due to temperature changes and practical component ageing, or, other general channel offsets. This can be considered advantageous and simpler when compared to more established approaches which characterize the coupling between elements or the response of the entire array in the near- or far-field for example

Attitude and Altitude Control of Trirotor UAV by Using Adaptive Hybrid Controller

The paper presents an adaptive hybrid scheme which is based on fuzzy regulation, pole-placement, and tracking (RST) control algorithm for controlling the attitude and altitude of trirotor UAV. The dynamic and kinematic model of Unmanned Aerial Vehicle (UAV) is unstable and nonlinear in nature with 6 degrees of freedom (DOF); that is why the stabilization of aerial vehicle is a difficult task. To stabilize the nonlinear behavior of our UAV, an adaptive hybrid controller algorithm is used, in which RST controller tuning is performed by adaptive gains of fuzzy logic controller. Simulated results show that fuzzy based RST controller gives better robustness as compared to the classical RST controller

Mesin pembungkus nasi lemak

Pada era globalisasi ini, makanan tradisi melayu semakin berkembang dengan permintaan yang sentiasa meningkat saban tahun. Promosi hebat dan kesan media sosial telah menyebabkan tarikan yang kuat terhadap makanan tradisional Malaysia ditambah pula dengan kaedah hiasan yang kreatif dan menarik. Antara makanan tradisi melayu yang mendapat permintaan tinggi adalah Nasi Lemak. Nasi Lemak sangat sinonim dengan negara Malaysia sehinggakan ianya menjadi menu tetap sarapan pagi bagi setiap gerai mahupun hotel di negara kita. Penjualan nasi lemak sangat popular dan meluas. Permintaannya meningkat bukan sahaja di dalam negara, bahkan di peringkat antarabangsa juga nasi lemak mempunyai peminatnya yang tersendiri. Bagi syarikat penerbangan milik Malaysia seperti Airsia dan MAS, Nasi Lemak menjadi pilihan hidangan untuk penumpangnya yang terdiri daripada pelbagai warganegara serata dunia. Selain itu, faktor berlakunya peningkatan permintaan terhadap nasi lemak adalah kerana ianya tidak lagi hanya menjadi menu sarapan pagi semata-mata, malah ia juga menjadi menu makanan sepanjang masa sehingga ke lewat malam

A Survey on Recent Trends of PIO and Its Variants Applied for Motion Planning of Dynamic Agents

Pigeon Inspired Optimization (PIO) algorithm is gaining popularity since its development due to faster convergence ability with great efficiencies when compared with other bio-inspired algorithms. The navigation capability of homing pigeons has been precisely used in Pigeon Inspired Optimization algorithm and continuous advancement in existing algorithms is making it more suitable for complex optimization problems in various fields. The main theme of this survey paper is to introduce the basics of PIO along with technical advancements of PIO for the motion planning techniques of dynamic agents. The survey also comprises of findings and limitations of proposed work since its development to help the research scholar around the world for particular algorithm selection especially for motion planning. This survey might be extended up to application based in order to understand the importance of algorithm in future studies

Motion Planning of UAV Swarm: Recent Challenges and Approaches

The unmanned aerial vehicle (UAV) swarm is gaining massive interest for researchers as it has huge significance over a single UAV. Many studies focus only on a few challenges of this complex multidisciplinary group. Most of them have certain limitations. This paper aims to recognize and arrange relevant research for evaluating motion planning techniques and models for a swarm from the viewpoint of control, path planning, architecture, communication, monitoring and tracking, and safety issues. Then, a state-of-the-art understanding of the UAV swarm and an overview of swarm intelligence (SI) are provided in this research. Multiple challenges are considered, and some approaches are presented. Findings show that swarm intelligence is leading in this era and is the most significant approach for UAV swarm that offers distinct contributions in different environments. This integration of studies will serve as a basis for knowledge concerning swarm, create guidelines for motion planning issues, and strengthens support for existing methods. Moreover, this paper possesses the capacity to engender new strategies that can serve as the grounds for future work

Printed Leaky-Wave Antenna with Aperture Control using Width-Modulated Microstrip Lines and TM Surface-Wave Feeding by SIW Technology

This letter presents a width-modulated microstrip line leaky-wave antenna (LWA) with substrate-integrated waveguide and microstrip feeding. In particular, the planar antenna system consists of an integrated surface-wave launcher and three identical rows of quasi-periodic width-modulated microstrip lines for TM leaky-wave excitation, which produces a tailored binomial-like aperture distribution on the guiding surface. The behavior of the antenna when changing the width-modulated lines for different aperture distributions is also analyzed and presented. The measured LWA demonstrates a fan beam pattern in the far field with realized gain values greater than 10 dBi and with a beam direction of about −20◦ from broadside at 23 GHz. Also, far-field measurements and near-field data indicate that the half-power beamwidth is below10◦, and the position of the main beam maximum is relatively stable, i.e., ranging from about −23◦ to −15◦ between 23 and 24 GHz. The measured prototype is also well matched over these frequencies and |S11| < −20 dB at 23.5 GHz

Cryptic footprints of rare earth elements on natural resources and living organisms

Background: Rare earth elements (REEs) are gaining attention due to rapid rise of modern industries and technological developments in their usage and residual fingerprinting. Cryptic entry of REEs in the natural resources and environment is significant; therefore, life on earth is prone to their nasty effects. Scientific sectors have expressed concerns over the entry of REEs into food chains, which ultimately influences their intake and metabolism in the living organisms. Objectives: Extensive scientific collections and intensive look in to the latest explorations agglomerated in this document aim to depict the distribution of REEs in soil, sediments, surface waters and groundwater possibly around the globe. Furthermore, it draws attention towards potential risks of intensive industrialization and modern agriculture to the exposure of REEs, and their effects on living organisms. It also draws links of REEs usage and their footprints in natural resources with the major food chains involving plants, animals and humans. Methods: Scientific literature preferably spanning over the last five years was obtained online from the MEDLINE and other sources publishing the latest studies on REEs distribution, properties, usage, cycling and intrusion in the environment and food-chains. Distribution of REEs in agricultural soils, sediments, surface and ground water was drawn on the global map, together with transport pathways of REEs and their cycling in the natural resources. Results: Fourteen REEs (Ce, Dy, Er, Eu, Gd, Ho, La, Lu, Nd, Pr, Sm, Tb, Th and Yb) were plighted in this study. Wide range of their concentrations has been detected in agricultural soils (\u3c 15.9–249.1 μg g−1) and in groundwater (\u3c 3.1–146.2 μg L−1) at various sites worldwide. They have strong tendency to accumulate in the human body, and thus associated with kidney stones. The REEs could also perturb the animal physiology, especially affecting the reproductive development in both terrestrial and aquatic animals. In plants, REEs might affect the germination, root and shoot development and flowering at concentration ranging from 0.4 to 150 mg kg−1. Conclusions: This review article precisely narrates the current status, sources, and potential effects of REEs on plants, animals, humans health. There are also a few examples where REEs have been used to benefit human health. However, still there is scarce information about threshold levels of REEs in the soil, aquatic, and terrestrial resources as well as living entities. Therefore, an aggressive effort is required for global action to generate more data on REEs. This implies we prescribe an urgent need for inter-disciplinary studies about REEs in order to identify their toxic effects on both ecosystems and organisms

Self‐calibrating circuit for phase correction to support phased array antenna systems

Abstract A self‐calibrating circuit system for use within active phased array antennas is presented. The system addresses the issue of unwanted channel phase imbalances and random phase errors which can deteriorate array performance. Basically, unwanted insertion phase offsets that can originate within each RF channel, due to the supporting and active circuit components and possible temperature variations, can be eliminated by our designed, simulated, and experimentally verified self‐calibrating circuit. With existing technologies and calibration approaches, it is practically difficult and time consuming to check the phase feeding accuracy, as typically a large number of data sets are required to achieve similar channel corrections. As an alternative, our proposed circuit system allows for the consecutive phase shift between RF channels to be inspected and self‐corrected within a feedback loop managed by a MATLAB‐Arduino program. The active S‐band feed system can self‐calibrate in about 25 s (or less), using commercially available phase sensors and voltage controlled phase shifters. To the best knowledge of the authors, no similar computer controlled feed‐back circuit to support the self‐correction of active phased arrays has been previously reported

A Computer Controlled Phase and Magnitude Self-Calibration Methodology for Phased Array Antennas

A circuit-based calibration system is presented for active phased arrays. In particular, to achieve the desired (and corrected) consecutive phase differences and relative magnitudes between RF channels, a computer controlled circuit system was developed for dynamic adjustment. The proof-of-concept demonstrator uses a phase sensor, phase shifters (PSs), and variable gain amplifiers, along with other active hardware, to realize a self-calibrating circuit system which achieves the required magnitude and phase for each array element. In addition, measured magnitude and phase imbalances are less than 0.10 dB and 3∘, respectively. The computer-controlled feed network is then used to demonstrate that the system can automatically calibrate an active antenna array for various beam steering examples. Also, the S-band feed system can self-calibrate due to any monitored magnitude and phase drifts due to temperature changes and practical component ageing, or, other general channel offsets. This can be considered advantageous and simpler when compared to more established approaches which characterize the coupling between elements or the response of the entire array in the near- or far-field for example