Impact of PWM Control Frequency onto Efficiency of a 1 kW Permanent Magnet Synchronous Motor

The paper explains how to select the best PWM control frequency for specific Permanent Magnet Synchronous Motors (PMSM) to achieve its maximum efficiency. Examinations were carried out for a PMSM unit with the power of 1 kW, rated speed of 1000 rpm and rated torque of 6 Nm. The PWM frequency ranged from 4 kHz to 20 kHz with the increment of 1 kHz. Measurements were taken for each of the foregoing frequencies, for the load torques of 2 Nm, 4 Nm and 6 Nm and for the rotation speeds of 300 rpm, 500 rpm, 750 rpm, 1000 rpm and 1200 rpm to find out efficiency of the PMSM motor. The achieved results make it possible to properly adjust the PWM control frequency for each PMSM motor to operate the motor in the most efficient way and, in consequence, save energy consumed by that motor

Priority-Aware Packet Pre-marking for DiffServ Architecture Based on H.264/SVC Video Stream Structure

The H264/SVC codec allows for generation of hierarchical video streams. In the stream of this type video data belonging to different layers have different priority depending on their importance to the quality of the video and the decoding process. This creates new demands on the mechanisms of packet marking, and thus new challenges for the policy guaranteeing QoS parameters, such as those defined in the DiffServ architecture. Therefore, mechanisms of the traffic engineering used in the DiffServ network should, as far as possible, take into account internal distribution of priorities inside video streams. This may be achieved by implementing an appropriate method for packet pre-marking. The paper describes the Weighted Priority Pre-marking (WPP) algorithm for priority-aware SVC video streaming over a DiffServ network. Our solution takes into account the relative importance of the Network Abstraction Layer Units. It also does not require any changes in the implementation of the DiffServ marker algorithm. The results presented confirm that video transmission in the DiffServ domain, based on the WPP packet pre-marking, can provide better perceived video quality than the standard (best effort) streaming of multi-layered SVC video. In addition, a comparison with the transmission of the same video content encoded with the H264/AVC codec also points to the superiority of our proposed method. Document type: Articl

An Integrated Power Supplying System for a Plasma Reactor

Plasma reactors demand unique requirements of their power sources such as high-voltage output, variable frequency and a current limiting capability. This paper shows a new means of providing power to a plasma reactor based on a magnetic frequency tripler and transformer. The integration of the tripler and transformer allows one to obtain improved operating characteristics and power utilization compared to othr conventional types of power sources

The simulation study on the multipath adaptive video transmission

The article presents simulation studies of multipath video transmission implemented as a live monitoring system based on adaptive streaming mechanisms. The transmission network consists of the Wi-Fi infrastructure and a single LTE cell. Both wireless networks are used during the operation of the video monitoring system. The analysis of the obtained results allows us to compare the features of two currently used multipath transmission protocols, MultiPath Quick UDP Internet Connections (MPQUIC) and MultiPath TCP (MPTCP) in the context of their use in adaptive video streaming systems. Also, the article contains a summary of the perceived advantages and disadvantages of using several transmission networks simultaneously for the implementation of video surveillance and monitoring systems

An inexpensive environmental monitoring system with IoT agents

Air quality is of great importance for human health and life expectancy. It becomes crucial to monitor atmospheric dust in the air of cities. In connection with the development of mobile networks and low-cost sensory agents, it has become possible to create inexpensive environmental monitoring systems. The paper presents results of studies on the system monitoring dust concentration in city air. The system consists of moving IoT agents placed on vehicles (taxies, busses, private cars) and measure the dust concentration. Agents, using a wireless connection, are sending the data to the recording server. The server application collects the data and visualises them on the map in a certain colour, depending on the dust concentration in the air and the values acceptable by standards. The system architecture, the algorithm of measurements and the agent-server data exchange protocol were presented in the article, as well as the example of data visualisation

Finite state machine logic synthesis for complex programmable logic devices

This book is a monograph devoted to logic synthesis and optimization for CPLDs. CPLDs' macrocell can also be interpreted as programmable AND-fixed OR structure, well known as PAL-based structure. The question is: what should be done when the number of implicants representing function exceeds the number of product terms available in a logic block. The answer is ... in the book. Logic synthesis and optimization methods dedicated for PAL-based structures are proposed. The methods strive to find the optimum fit for the combinational logic and finite state machines to the structure of the logic device and aim at area and speed optimization. The theoretical background and complete strategies are richly illustrated with examples and figures

Jammers signal power modelling in the Wi-Fi band

The distribution of the signal coming from jamming sources is an issue of critical importance to the security and jammer localisation. The paper presents the results of simulations of signal power distribution in the Wi-Fi band conducted for two commercially available jammers, CRJ4000 and CKJ-1502A12. Calculated distributions of signal power were compared with the results from the measurements. The comparison made it possible to assess the correctness of the designed models and out of the simulations. The paper presents the results of simulations and measurements for different scenarios of jammers settings

Sensitive Metal-Semiconductor Nanothermocouple Fabricated by FIB to Investigate Laser Beams with Nanometer Spatial Resolution

The focused ion beam (FIB) technique was used to fabricate a nanothermocouple (with a 90 nm wide nanojunction) based on a metal–semiconductor (Pt–Si) structure, which showed a sensitivity up to 10 times larger (with Seebeck coefficient up to 140 µV/K) than typical metal–metal nanothermocouples. In contrast to the fabrication of nanothermocouples which requires a high-tech semiconductor manufacturing line with sophisticated fabrication techniques, environment, and advanced equipment, FIB systems are available in many research laboratories without the need for a high-tech environment, and the described processing is performed relatively quickly by a single operator. The linear response of the manufactured nanothermocouple enabled sensitive measurements even with small changes of temperature when heated with a stream of hot air. A nonlinear response of the nanothermocouple (up to 83.85 mV) was observed during the exposition to an argon-laser beam with a high optical power density (up to 17.4 Wcm−2), which was also used for the laser annealing of metal–semiconductor interfaces. The analysis of the results implies the application of such nanothermocouples, especially for the characterization of laser beams with nanometer spatial resolution. Improvements of the FIB processing should lead to an even higher Seebeck coefficient of the nanothermocouples; e.g., in case of the availability of other suitable metal sources (e.g., Cr)