Effect of Location Accuracy and Shadowing on the Probability of Non-Interfering Concurrent Transmissions in Cognitive Ad Hoc Networks

Cognitive radio ad hoc systems can coexist with a primary network in a scanning-free region, which can be dimensioned by location awareness. This coexistence of networks improves system throughput and increases the efficiency of radio spectrum utilization. However, the location accuracy of real positioning systems affects the right dimensioning of the concurrent transmission region. Moreover, an ad hoc connection may not be able to coexist with the primary link due to the shadowing effect. In this paper we investigate the impact of location accuracy on the concurrent transmission probability and analyze the reliability of concurrent transmissions when shadowing is taken into account. A new analytical model is proposed, which allows to estimate the resulting secure region when the localization uncertainty range is known. Computer simulations show the dependency between the location accuracy and the performance of the proposed topology, as well as the reliability of the resulting secure region

Systems of Preventive Cardiological Monitoring: Models, Algorithms, First Results, and Perspectives

The results of work on creating methods, models, and computational algorithms for remote preventive health-monitoring systems are presented, in particular, cardiac preventive monitoring. The main attention is paid to the models and computational algorithms of preventive monitoring, the interaction of the computing kernels of a remote cluster with portable ECG recorders, implantable devices, and sensors. Computational kernels of preventive monitoring are a set of several thousand interacting automata of analog of Turing machines, recognizing the characteristic features and evolution of the hidden predictors of atrial fibrillation(AF), ventricular tachycardia or fibrillation (VT-VF), sudden cardiac death, and heart failure (HF) revealed by them. The estimation of the time for reaching the heart events boundaries is calculated on the basis of the evolution equations for the ECG multi-trajectories determined by recognizing automata. Evaluation time of heart event (HE) boundaries to achieve is calculated on the basis of the evolution equations for ECG multi-paths defined by recognizing machines. Ultimately, the computational cores reconstruct the ECG of the forecast and give temporary estimates of its achievement. Cloud computing cluster supports low-cost ECG ultra-portable recorders and does not limit the possibilities of using a more complex patient telemetry containing wearable and implantable devices: CRT and ICD, CardioMEMS HF System, and so on

Electrothermal Modelling for Doubly Fed Induction Generator Converter Reliability in Wind Power

Increased reliance upon renewable energy sources, chiefly wind, places a growing emphasis on the reliability of the technology used in Wind Turbines. The current Wind Turbine fleet is dominated by the Doubly Fed Induction Machine WT, which utilises a partially rated power electronic converter to vary the speed of the rotor and thus ensure the maximum energy capture available from the wind. This converter is associated with a significant percentage of WT failures. This thesis examines the low frequency temperature cycling occurring in one half of the back to back converter which results in a high failure rate of the rotor side converter as compared to the grid side converter. To this end a MATLAB/PLECS model was constructed to demonstrate the temperature cycling occurring in a 2.5MW DFIG WT. Lifetime of the semiconductor devices was extrapolated. An adaptation to the standard Maximum Power Point Tracking control method was suggested in which the lowest operating frequencies (less than 2.33Hz) were avoided. In doing so, lifetime was observed to increase at a minor cost to energy yield from the WT

Analysis of a total integration of renewable energy through a dynamic virtual power plant model and the use of hydrogen as a method of energy production stabilization

The growing need for change in the energy vector, the increasing popularity of renewable energies, as well as the European regulations to achieve zero emissions by 2050 (currently at 21.8% in Europe with a projection of 42.5% by 2030), prompt the analysis of scenarios for meeting the annual demand in three autonomous communities (Andalusia and Valencia) while considering the current electric grid and a new scenario with the most optimal distribution. This analysis involves simplifying the grid and utilizing a distributed virtual power plant (DVPP). These scenarios consider increasing the share of renewables up to 99% and implementing hydrogen-based storage technologies to evaluate their economic impact on the levelized cost of energy and how it increases as the share of renewables grows. Prices for each available technology have been obtained to achieve a more realistic approximation. Variables such as capital expenditures (CAPEX), operating expenses (OPEX), fuel costs where applicable, and replacement costs have been considered, as the project analyses the system with a 50-year outlook, and some technologies have a lifespan shorter than this period. The obtained results will be used to analyse the capacities of hydrogen plants in terms of power and storage, as well as their behaviour in balancing the grid as a supporting technology for intermittent generation sources such as wind and photovoltaic, and for managing potential energy surpluse