Optimal Design of an Inductive MHD Electric Generator

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

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

Pola Tidur yang Buruk Meningkatkan Risiko Hipertensi

Pola tidur yang buruk yaitu gangguan tidur, kualitas tidur yang buruk, dan durasi tidur yang pendek dapat meningkatkan risiko hipertensi. Hipertensi sendiri kini menjadi penyakit yang menduduki posisi tinggi yang sering dialami oleh masyarakat. Tujuan dari penelitian ini untuk mengetahui hubungan perilaku tidur yang buruk dapat meningkatkan risiko kejadian hipertensi. Penelitian ini merupakan penelitian observasional yang bersifat analitik dengan desain case control. Sampel dalam penelitian ini berjumlah 76 orang yang terdiri dari penderita hipertensi dan bukan penderita hipertensi pada Poli Umum Puskesmas Tanah Kalikedinding Surabaya. Teknik pengambilan sampel yang dilakukan menggunakan simple random sampling. Hasil penelitian menggunakan uji statistik regresi logistik menunjukkan (p=0,000; OR=9,022) artinya pola tidur memiliki pengaruh paling besar terhadap kejadian hipertensi dibandingkan dengan umur dan jenis kelamin. Kekuatan pengaruh pola tidur responden menunjukkan bahwa responden yang memiliki pola tidur yang buruk memiliki risiko 9,022 kali lebih besar terserang hipertensi dibandingkan dengan yang memiliki pola tidur baik. Pola tidur buruk antara lain gangguan tidur, kualitas tidur yang buruk, dan durasi tidur yang pendek. Rekomendasi yang diberikan kepada responden yang memiliki pola tidur buruk harus memperbaiki pola tidur dengan gaya hidup yang sehat yaitu tidur sesuai kebutuhan dan menjaga pikiran supaya tidak mengalami tekanan karena stres yang berlebih

Forecasting-Aided Monitoring for the Distribution System State Estimation

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

Selection of features based on electric power quantities for non-intrusive load monitoring

Non-intrusive load monitoring (NILM) is a process of determining the operating states and the energy consumption of single electric devices using a single energy meter providing aggregate load measurements. Due to the large spread of power electronic-based and nonlinear devices connected to the network, the time signals of both voltage and current are typically non-sinusoidal. The effectiveness of a NILM algorithm strongly depends on determining a set of discriminative features. In this paper, voltage and current signals were combined to define, according to the definitions provided in Standard IEEE 1459, different power quantities, that can be used to distinguish different types of appliance. Multi-layer perceptron (MLP) classifiers were trained to solve the appliance detection problem as a multi-class event classification problem, varying the electric features in input. This allowed to select an optimal set of features guarantying good classification performance in identifying typical electric loads

A real time bolometer tomographic reconstruction algorithm in nuclear fusion reactors

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

Pemanfaatan Limbah Budidaya Ikan Lele (Clarias Gariepinus) sebagai Pakan Alami Ikan Peres (Osteochillus SP.) pada Sistem Resirkulasi

The objective of this research was to analyze the utilization of waste catfish farming as a commodity by utilizing phytoplankton growing up from the utilization of waste catfish  farming on cultivating a different stocking. This research was implemented on Fish Seed Hall (BBI) Lukup Rhino Subdistrict of Central Aceh district Pegasing in October – November 2015. This research used the completely randomized design which consists of 4 treatments and 3 replicates. Treatment is provided in the form of A fish Density: 1 head/1 liter of wastewater recirculation system cultivating catfish, fish Density B : 1 head/1.5 liter of wastewater recirculation system of cultivating catfish, fish Density C : 1 head/2 liters of wastewater recirculation aquaculture system of catfish, fish Density D : 1 head/2.5 liters of wastewater recirculation system of cultivating catfish stocked up on fruit with as many as 12 aquarium water volume 30 litres. Based on the results of research on the growth of weight gain the best results on the treatment of D with a value of 0.38 g and the lowest found in treatment A with a value of 0.28 gr, survival with the best results on the treatment A with 91.11% and the lowest refractory treatment C by the value 84.44%, the length of the intestine relatively with the best results at the treatment  A with 323% results and the lowest refractory treatment  C by the value of the 276%, the abundance of phytoplankton obtain Aphanocapsa sp. as phytoplankton most and least Oscillatoria sp, while the biggest part of the index getting most phytoplankton Aphanocapsa sp and the least Asterococcus sp. Penelitian ini bertujuan untuk menganalisis pemanfaatan limbah ikan lele sebagai komoditas tambahan dengan memanfaatkan fitoplankton yang tumbuh dari pemanfaatan limbah budidaya lele pada padat tebar yang berbeda. Penelitian ini dilaksanakan di Balai Benih Ikan (BBI) Lukup Badak Kecamatan Pegasing Kabupaten Aceh Tengah pada bulan Oktober – November 2015. Penelitian ini menggunakan Rancangan Acak Lengkap (RAL), yang terdiri dari 4 perlakuan dan 3 kali ulangan. Perlakuan yang diberikan adalah berupa A : Kepadatan ikan 1 ekor/ 1 liter pada sistem resirkulasi air limbah budidaya lele, B : Kepadatan ikan 1 ekor/ 1,5 liter pada sistem resirkulasi air limbah budidaya lele, C : Kepadatan ikan 1 ekor/ 2 liter pada sistem resirkulasi air limbah budidaya lele, D : Kepadatan ikan 1 ekor/ 2,5 liter pada sistem resirkulasi air limbah budidaya lele yang ditebar pada akuarium sebanyak 12 buah dengan volume air 30 liter. Berdasarkan hasil penelitian pada pertumbuhan bobot mendapatkan hasil yang terbaik pada­ perlakuan D dengan nilai 0,38 gr dan yang terendah terdapat pada perlakuan A dengan nilai 0,28 gr, kelangsungan hidup dengan hasil terbaik pada perlakuan A 91,11 % dan yang terendah terdapat pada perlakuan C dengan nilai 84,44 %, panjang usus relatif dengan hasil terbaik pada perlakuan A dengan hasil 323 % dan yang terendah terdapat pada perlakuan C dengan nilai 276 %, kelimpahan fitoplankton mendapatkan Aphanocapsa sp sebagai fitoplankton terbanyak dan yang paling sedikit Oscillatoria sp, sedangkan indeks bagian terbesar mendapatkan fitoplankton terbanyak Aphanocapsa sp dan yang paling sedikit Asterococcus sp

Computational Fluid Dynamics Simulations of an Innovative System of Wind Power Generation

Abstract: In this work an innovative system for wind power generation in urban areas is proposed. The generation system substitutes the roof of the building and it consists of a static part, the stator, and a moving part, called impeller or rotor, which is a centripetal turbine with vertical axis of rotation. The rotary motion of the rotor is transferred through a shaft to a generator that produces electricity. Since the objective is to conveying the air flow in the stator in order to avoid the formation of vortices, the logarithmic spiral has been chosen as the shape for the stator blades. A 2D and a 3D model of the system are analyzed in order to evaluate the efficiency of the new system proposed considering both the influence of the profile of the building and the effect of impedance of the duct on the available power to the impeller

Effects of Uncertainty of Outlet Boundary Conditions in a Patient-Specific Case of Aortic Coarctation

Computational Fluid Dynamics (CFD) simulations of blood flow are widely used to compute a variety of hemodynamic indicators such as velocity, time-varying wall shear stress, pressure drop, and energy losses. One of the major advances of this approach is that it is non-invasive. The accuracy of the cardiovascular simulations depends directly on the level of certainty on input parameters due to the modelling assumptions or computational settings. Physiologically suitable boundary conditions at the inlet and outlet of the computational domain are needed to perform a patient-specific CFD analysis. These conditions are often affected by uncertainties, whose impact can be quantified through a stochastic approach. A methodology based on a full propagation of the uncertainty from clinical data to model results is proposed here. It was possible to estimate the confidence associated with model predictions, differently than by deterministic simulations. We evaluated the effect of using three-element Windkessel models as the outflow boundary conditions of a patient-specific aortic coarctation model. A parameter was introduced to calibrate the resistances of the Windkessel model at the outlets. The generalized Polynomial Chaos method was adopted to perform the stochastic analysis, starting from a few deterministic simulations. Our results show that the uncertainty of the input parameter gave a remarkable variability on the volume flow rate waveform at the systolic peak simulating the conditions before the treatment. The same uncertain parameter had a slighter effect on other quantities of interest, such as the pressure gradient. Furthermore, the results highlight that the fine-tuning of Windkessel resistances is not necessary to simulate the post-stenting scenario