This paper describes a method for comparison exercise intensity (workload) based on oxygen consumption (V̇O 2 ) and carbon dioxide expenditure (V̇CO 2 ) during the bicycle ergometer and treadmill ergometer stress tests. During the stress test, values of heart rate (HR), pulmonary ventilation (V̇E), oxygen consumption and carbon dioxide expenditure were continuously measured from the start of the test until exhaustion. The main goal of the study was to find out whether it is possible to compare the value of the load intensity on a treadmill ergometer, where the load is characterized by the running speed and the incline, with the load on a bicycle ergometer, where the load is given in Watts. The results can also be used to possibly derive a mathematical model of the test subject. The results were confirmed by a number of measurements.
This paper presents three new non-isolated high step-up converters (NI-HSC) for electric vehicle charging applications. Higher duty ratios increase the overall gain of the step-up converter. However, this increases voltage and current stresses in the switching devices. This paper proposes three soft-switched high step-up converters (SS-HSC) improved with auxiliary cells, to reduce the switching losses and to improve the overall efficiency. The auxiliary cell provides soft-switching of the main MOSFETs. The zero voltage switching (ZVS) is achieved for all the MOSFETs during turn-on. Zero current switching (ZCS) turn-off is obtained for one main switch and the auxiliary switch. Principles of operation and simulation results are presented to evaluate the theoretical analysis. The designed converter systems are simulated with 100 V input voltage at 6 kW to obtain 600 V output voltage.
Power dividers are the most important tools in microwave systems such as mixers, frequency multipliers, and feeding networks in antennas. So far, in designing power dividers, various methods have been used to reduce the size and eliminate unwanted harmonics. In this paper, using a resonator structure and low pass filter, a Wilkinson power divider with I-shaped structure is designed, simulated, and fabricated. According to the results of the simulation, this structure has 6-harmonic elimination. The size of the designed power divider, due to the use of resonators, has dimensions of 0.06 × 0.07 λg 2 , which reflects a size reduction of 65% and indicates one of the advantages of this divider. The guided wavelength at the working frequency of the resonator is calculated at 0.97 GHz. This structure also has a relative working bandwidth of 42%, which indicates its wide operation band. The isolation value is −31 dB, which is another benefit of this power divider. This divider has been built and measured on the Rt-duroid 5880 substrate, where the responses from the simulation and real implementation have good match.
This paper presents an encryption algorithm based on a class of bio-inspired systems, namely cellular automata (CA). The proposed solution uses a combination of elementary evolution rules, specifically constructed to create a reversible system. Based on this propriety, encryption is performed by forward iteration of the system and the opposite process of decryption is done by backward iteration. The functionality of the system is achieved by using the same rule in both processes starting either from plaintext or from ciphertext along with some random initial data. To asses and test the system, a hardware implementation was performed based on reconfigurable devices. The main component of the system is the processing unit, implemented using a Field Programmable Gate Array (FPGA) which receives and sends back data to a software application developed using C# language.
This study paper explores the implementation of Intelligent Transportation Systems (ITS) in railway transportation, with a focus on level crossings, which have been a significant issue in railway safety. The paper discusses the limitations of current technologies such as laser technology and video surveillance and presents a novel solution utilizing a 79GHz Frequency Modulated Continuous Wave (FMCW) radar in combination with a CCTV camera for a dual sensor module. The FMCW radar is shown to be more accurate and cost-effective than previous technologies and can detect both large and small objects in the defined area at level crossings and difficult weather situations. The paper also presents a system architecture that takes into account vehicle detection time, which is crucial in reducing the risk of accidents and improving the safety of level crossings. This study aimed to compare the performance of different object detection modules under varying weather conditions. Three object detection methods were tested: a camera with the object detection algorithm Yolov5, FMCW radar with a built-in tracker, and manual observation. Four measurement sessions were conducted, each with a different combination of weather and time of day. The results showed that all modules performed similarly well under clear weather conditions, with the camera and radar modules detecting all vehicles approaching. However, under rainy and dark conditions, the radar module outperformed the camera, detecting 5 more objects.
