In this study, we present options for extending the endurance of a lightweight unmanned aerial vehicle (UAV), along with their advantages and disadvantages. We present a developed solution based on the use of gallium–arsenide (GaAs) solar modules installed on a UAV and connected to a custom-made maximum power point tracker (MPPT) with an integrated perturb and observe (P&O) algorithm. The mathematical behavior required to calculate the electrical energy production from solar energy on the UAV from known UAV angles of rotation, the position of the sun in the sky, solar irradiance measurements, the solar module area and the solar modules efficiency is presented. A comparison of the calculated and actual measured electrical energy production results during an aerial mapping mission is presented. We perform a number of aerial mapping mission flights and the experimental results confirm an energy efficiency value of more than 96.27% for the MPPT and extended flight endurance by up to 21.25%. In addition, onboard measurements and other data captured during flights confirm the proposed electrical energy production calculation.

In this work, we present an eye-image acquisition device that can be used as an image acquisition front-end application in compact, low-cost, and easy-to-integrate products for smart-city access control applications, based on iris recognition. We present the advantages and disadvantages of iris recognition compared to fingerprint- or face recognition. We also present the main drawbacks of the existing commercial solutions and propose a concept device design for door-mounted access control systems based on iris recognition technology. Our eye-image acquisition device was built around a low-cost camera module. An integrated infrared distance measurement was used for active image focusing. FPGA image processing was used for raw-RGB to grayscale demosaicing and passive image focusing. The integrated visible light illumination meets the IEC62471 photobiological safety standard. According to our results, we present the operation of the distance-measurement subsystem, the operation of the image-focusing subsystem, examples of acquired images of an artificial toy eye under different illumination conditions, and the calculation of illumination exposure hazards. We managed to acquire a sharp image of an artificial toy eye sized 22 mm in diameter from an approximate distance of 10 cm, with 400 pixels over the iris diameter, an average acquisition time of 1 s, and illumination below hazardous exposure levels.

Hardware description languages and tools require a considerable amount of teaching activities in a digital systems design course, which is difficult to accommodate in a limited time frame, and to use for e-learning. This paper presents our user-friendly and open-source web-based digital design tool, SHDL, which is used to describe and simulate hardware components and translate them into a standard language. SHDL is a teaching language and tool for digital design, which aims to improve the teaching and learning experience in digital systems design courses. The use and evaluation of the proposed online teaching model for the Digital Electronic Systems Design (DESD) course, using the SHDL tool for e-learning during the COVID-19 phase, is presented. Using the SHDL language and web tool, we have created many examples of digital circuits that prepare students to explore their own designs. The example components can also be used as digital system modules, leading to better modularity of the final project. The use of SHDL in the DESD course has shown that the proposed language leads to fewer syntax, simulation and synthesis errors in the designed circuits. The evaluation results show that at the end of the laboratory exercises, there was no longer a difference in knowledge between the students without prior VHDL experience and the other students. The results encourage us to continue using SHDL, and to complement the traditional DESD teaching methods with e-learning.

The ability to modify digital images can cause a serious problem in some applications. In this paper we propose a novel method derived from Wong’s authentication scheme that is capable of authenticating JPEG images as well as uncompressed images, but is not a watermarking method. The method offers great flexibility in terms of the size of the authenticator and the time needed to generate the authenticator, thus making it suitable for real-time image processing. We demonstrate this by implementing it in a programmable FPGA circuit.