1,040 research outputs found

    Dynamic control of modern, network-based epidemic models

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    In this paper we make the first steps to bridge the gap between classic control theory and modern, network-based epidemic models. In particular, we apply nonlinear model predictive control (NMPC) to a pairwise ODE model which we use to model a susceptible-infectious-susceptible (SIS) epidemic on nontrivial contact structures. While classic control of epidemics concentrates on aspects such as vaccination, quarantine, and fast diagnosis, our novel setup allows us to deliver control by altering the contact network within the population. Moreover, the ideal outcome of control is to eradicate the disease while keeping the network well connected. The paper gives a thorough and detailed numerical investigation of the impact and interaction of system and control parameters on the controllability of the system. For a certain combination of parameters, we used our method to identify the critical control bounds above which the system is controllable. We foresee that our approach can be extended to even more realistic or simulation-based models with the aim of applying these to real-world situations

    Optimal Design of an Inductive MHD Electric Generator

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    In this paper, the problem of optimizing the design of an inductive Magneto-Hydro-Dynamic (MHD) electric generator is formalized as a multi-objective optimization problem where the conflicting objectives consist of maximizing the output power while minimizing the hydraulic losses and the mass of the apparatus. In the proposal, the working fluid is ionized with periodical pulsed discharges and the resulting neutral plasma is unbalanced by means of an intense DC electrical field. The gas is thus split into two charged streams, which induce an electromotive force into a magnetically coupled coil. The resulting generator layout does not require the use of superconducting coils and allows you to manage the issues related to the conductivity of the gas and the corrosion of the electrodes, which are typical limits of the MHD generators. A tailored multi-objective optimization algorithm, based on the Tabu Search meta-heuristics, has been implemented, which returns a set of Pareto optimal solutions from which it is possible to choose the optimal solution according to further applicative or performance constraints

    Optimization of a power line communication system to manage electric vehicle charging stations in a smart grid

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    In this paper, a procedure is proposed to design a power line communication (PLC) system to perform the digital transmission in a distributed energy storage system consisting of fleets of electric cars. PLC uses existing power cables or wires as data communication multicarrier channels. For each vehicle, the information to be transmitted can be, for example: the models of the batteries, the level of the charge state, and the schedule of charging/discharging. Orthogonal frequency division multiplexing modulation (OFDM) is used for the bit loading, whose parameters are optimized to find the best compromise between the communication conflicting objectives of minimizing the signal power, maximizing the bit rate, and minimizing the bit error rate. The off-line design is modeled as a multi-objective optimization problem, whose solution supplies a set of Pareto optimal solutions. At the same time, as many charging stations share part of the transmission line, the optimization problem includes also the assignment of the sub-carriers to the single charging stations. Each connection between the control node and a charging station has its own frequency response and is affected by a noise spectrum. In this paper, a procedure is presented, called Chimera, which allows one to solve the multi-objective optimization problem with respect to a unique frequency response, representing the whole set of lines connecting each charging station with the central node. Among the provided Pareto solutions, the designer will make the final decision based on the control system requirements and/or the hardware constraints

    A real time bolometer tomographic reconstruction algorithm in nuclear fusion reactors

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    In tokamak nuclear fusion reactors, one of the main issues is to know the total emission of radiation, which is mandatory to understand the plasma physics and is very useful to monitor and control the plasma evolution. This radiation can be measured by means of a bolometer system that consists in a certain number of elements sensitive to the integral of the radiation along straight lines crossing the plasma. By placing the sensors in such a way to have families of crossing lines, sophisticated tomographic inversion algorithms allow to reconstruct the radiation tomography in the 2D poloidal cross-section of the plasma. In tokamaks, the number of projection cameras is often quite limited resulting in an inversion mathematic problem very ill conditioned so that, usually, it is solved by means of a grid-based, iterative constrained optimization procedure, whose convergence time is not suitable for the real time requirements. In this paper, to illustrate the method, an assumption not valid in general is made on the correlation among the grid elements, based on the statistical distribution of the radiation emissivity over a set of tomographic reconstructions, performed off-line. Then, a regularization procedure is carried out, which merge highly correlated grid elements providing a squared coefficients matrix with an enough low condition number. This matrix, which is inverted offline once for all, can be multiplied by the actual bolometer measures returning the tomographic reconstruction, with calculations suitable for real time application. The proposed algorithm is applied, in this paper, to a synthetic case study

    The Use of Big Book to Increase Students English Early Reading Skills

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    The purpose of this research was to find out the effectiveness of Big Book in increasing students' english early reading skills. The method used was a pre experimental design. The sample of this research was class B kindergarten of Rumah Matematika dan Sains. The tool of data collecting was oral reading test. T-test and effect size formula used to measure the effectiveness of the treatment. After the treatment, the students' english early reading skills increased, they aware of the letter sounds, and they become familiar with the words . The data showed their score in letter sounds ,familiar word reading, and sentences reading increased. The findings showed that the t-test 27.879 was higher than the ttable (27.879 > 2.930). the effect size results was 1.39 (ES > 0.80) which was classified as high. Based on the results the use of big book was effective to increase students english early reading skills

    Forecasting-Aided Monitoring for the Distribution System State Estimation

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    In this paper, an innovative approach based on an artificial neural network (ANN) load forecasting model to improve the distribution system state estimation accuracy is proposed. High-quality pseudomeasurements are produced by a neural model fed with both exogenous and historical load information and applied in a realistic measurement scenario. Aggregated active and reactive powers of small or medium enterprises and residential loads are simultaneously predicted by a one-step ahead forecast. The correlation between the forecasted real and reactive power errors is duly kept into account in the definition of the estimator together with the uncertainty of the overall measurement chain. The beneficial effects of the ANN-based pseudomeasurements on the quality of the state estimation are demonstrated by simulations carried out on a small medium-voltage distribution grid

    Studi Perubahan Nilai Tanah Dan Penggunaan Lahan Pada Daerah Rawan Genangan Banjir Rob Di Kecamatan Semarang Utara

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    North Semarang sub-district has a topography with a slope of 0-2%. The lower area of sea surface will be flooded if the sea surface keep increase with landsubsidence, and also caused by optimallyzation landuse around the coastal area.This research using some secondary data. From the process of merging spotheight with the landsubsidence value every year and then classified by the highest tides, the average of sea level and the lowest tides so obtained the form of tidal inudation area. The fix tidal inudation area model will be overlay with the map of landuse and the land value of North Semarang sub-district. The method used is analysis data based on Geographic Information System with seeing the real condition of the field.The research result shows that the safe area has decrease by 35,5 acres within a period of 7 years. It caused by land use changes such as increase of industry area by 45,3 acres within a period of 5 years. The selling price of land in subcript tidal inudation area such as Tanjung Mas village has increased by Rp. 28.000,00 with AD ground code within a period of 5 years whereas the safe area with AD ground code such as Plombokan village has increased by Rp. 559.000,00 within a period of 5 years
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