A Low Cost Shading Analyzer and Site Evaluator Design to Determine Solar Power System Installation Area

Shading analyzer systems are necessary for selecting the most suitable installation site to sustain enough solar power. Afterwards, changes in solar data throughout the year must be evaluated along with the identification of obstructions surrounding the installation site in order to analyze shading effects on productivity of the solar power system. In this study, the shading analysis tools are introduced briefly, and a new and different device is developed and explained to analyze shading effect of the environmental obstruction on the site on which the solar power system will be established. Thus, exposure duration of the PV panels to the sunlight can be measured effectively. The device is explained with an application on the installation area selected as a pilot site, Denizli, in Turkey

Učinkovito upravljanje brzinom induktivnog motora korištenjem metode adaptivnog upravljanja s referentnim modelom zasnovane na RBF-u

This paper proposes a model reference adaptive speed controller based on artificial neural network for induction motor drives. The performance of traditional feedback controllers has been insufficient in speed control of induction motors due to nonlinear structure of the system, changing environmental conditions, and disturbance input effects. A successful speed control of induction motor requires a nonlinear control system. On the other hand, in recent years, it has been demonstrated that artificial intelligence based control methods were much more successful in the nonlinear system control applications. In this work, it has been developed an intelligent controller for induction motor speed control with combination of radial basis function type neural network (RBF) and model reference adaptive control (MRAC) strategy. RBF is utilized to adaptively compensate the unknown nonlinearity in the control system. The indirect field-oriented control (IFOC) technique and space vector pulse width modulation (SVPWM) methods which are widespread used in high performance induction motor drives has been preferred for drive method. In order to demonstrate the reliability of the control technique, the proposed adaptive controller has been tested under different operating conditions and compared performance of conventional PI controller. The results show that the proposed controller has got a clear superiority to the conventional linear controllers.Ovaj rad prikazuje adaptivni regulator s referentnim modelom zasnovan na neuronskoj mreži za induktivne motore. Ponašanje tradicionalnih regulatora s povratnom vezom pokazalo se nedovoljno dobrom za upravljanje brzinom induktivnih motora zbog nelineatnosti strukture sustava, promjene okolišnih uvjeta, i efekta ulaznih poremećaja. Uspješno upravljanje brzinom induktivnog motora zahtjeva nealinearne upravljačke sustave. S druge strane, posljednjih godina pokazano je kako su upravljačke metode zasnovane na umjetnoj inteligenciji bitno uspješnije u primjenama upravljanja nelinearnim sustavima. U ovome radu razvijen je inteligentni regulator za upravljanje brzinom induktivnog motora s kombinacijom radijalne neuronske mreže (RBF) i strategije adaptivnog regulatora s referentnim modelom (MRAC). RBF je realiziran kako bi adaptivno kompenzirao nepoznatu nelinearnost u sustavu upravljanja. Tehnika indirektnog vektorskog upravljanja (IFOC) i metoda prostorno vektorske širinsko impulsne modulacije koje su široko korištene za induktivne motore visokih performansi preferirani su kao metode u ovome radu. Kako bi se prikazala pouzdanost tehnike upravljanja, predloženi adaptivni regulator ispitan je u različitih uvjetima rada i uspoređeno je vladanje s obzirom na konvencionalni PI regulator. Rezultati pokazuju kako predloženi regulator očito pokazuje bolje vladanje od konvencionalnih linearnih regulatora

THE CRYSTAL FIELD EFFECTS ON THE PHASE DIAGRAMS OF THE SPIN-2 BILAYER BETHE LATTICE

The bilayer spin-2 Ising model on the Bethe lattice is investigated by taking into account the intralayer coupling constants of the two layers J(1) and J(2), interlayer coupling constant between the layers J(3) and crystal field interaction Delta by using the exact recursion equations in a pairwise approach. The ground state (GS) phase diagrams of the model are obtained on the (J(2)/vertical bar J(1)vertical bar, J(3)/q vertical bar J(1)vertical bar) planes for given Delta values and on the (Delta/qJ, J(3)/qJ) plane when J(1) = J(2) = J, and thus 33 distinct GS configurations are found. The temperature-dependent phase diagrams are obtained for J(1) > 0, J(2) > 0, and for J(3) > 0 or J(3) < 0 on the (kT/J(1), J(3)/J(1)) planes for given Delta/qJ(1) and J(2)/J(1) and on the (Delta/J, kT/J) plane for given J(3)/J when J(1) = J(2) = J for the coordination number q = 3. It was found that the system exhibits both first- and second-order phase transitions and tricritical points. The paramagnetic phases are also classified by studying the thermal variations of the quadrupolar moments

A study of the bilayer Bethe lattice for spin-3/2 Ising model

The spin-3/2 Ising model on the bilayer Bethe lattice is studied in terms of the exact recursion relations with the intralayer bilinear interactions J(11) and J(22) of the two layers with ferromagnetic coupling and interlayer bilinear interaction J(12) between the layers with ferromagnetic or antiferromagnetic coupling. We first have obtained the ground state configurations of the model on the (J(22)/vertical bar J(11)vertical bar,J(21)q/vertical bar J(11)) planes for J(11) 0. Then the thermal behaviors of the order-parameters, the total and staggered magnetizations of the two layers and also the spin-spin correlation function between the nearest-neighbor spins of the adjacent layers, are studied to obtain the phase diagrams of the model on the (kT/J(11),J(12)/J(11)) plane for given values of J(22)/J(11) and the coordination number q. As a result, a few types of the critical temperatures of the model are obtained. (c) 2006 Elsevier B.V. All rights reserved

Synthesis of boron nitride nanotubes from unprocessed colemanite

Colemanite (Ca2B6O11·5H2O) is a natural and new precursor material for the synthesis of boron nitride nanotubes (BNNTs). BNNTs have been synthesized from unprocessed colemanite for the first time. The reaction parameters such as time, catalyst type, catalyst amount and temperature were optimized. It was found that the BNNT formation follows the base growth mechanism, which was initiated with a complex of boron nitride (BN) and iron atoms. The obtained BNNTs were characterized by using SEM, TEM, and spectroscopic techniques such as UV–vis, Raman, FTIR and XRD. The BNNTs were randomly oriented and multi-walled with an outer diameter of 10–30 nm and a wall thickness of 5 nm. This novel BNNT synthesis method can be used to obtain high yield, low cost and pure BNNTs

The spin-3/2 bilayer Bethe lattice with crystal field

The phase diagrams of the bilayer spin-(3)/(2) Ising model on the Bethe lattice is analyzed by taking into account the intralayer coupling constants of the two layers (J(1), J(2)), interlayer coupling constant between the layers (J(3)) and crystal field interaction (D) for the coordination number q = 3 by using the exact recursion equations. First, the distinct ground state phase diagrams of the model are obtained on the (J(2)/vertical bar J(1)vertical bar, J(3)/q vertical bar J vertical bar(1)) plane with J(1) > 0 for given crystal field values. Then, the phase diagrams of the system are obtained on the (kT/J(1),J(3)/J(1)) planes for given values of the crystal field and alpha = J(2)/J] on the honeycomb lattice, i.e., q = 3. It was found that the system presents both first- and second-order phase transitions, therefore, tricritical points, and splitting of the critical lines at negative values of the crystal field. The paramagnetic phases are also classified by studying the thermal variations of the quadrupolar moments. (c) 2007 Elsevier B.V. All rights reserved

SPIN-2ISING MODEL ON THE BILAYER BETHE LATTICE

A spin-2 system consisting of two layers of Bethe lattices each with a branching ratio of q Ising spins was analyzed by the use of the exact recursion relations in a pairwise approach. The upper layer interacting with nearest-neighbor (NN) bilinear interaction J(1) is laid over the top of the lower layer interacting with bilinear NN interaction J(2), and the two layers are tied together via the bilinear interaction between the vertically aligned adjacent NN spins denoted as J(3). The study of the ground state phase diagrams on the (J(2)/vertical bar J(3)vertical bar, J(1)/vertical bar J(3)vertical bar) plane with J(3) > 0 and J(3) 0 and on the (J(2)/J(1), J(3)/qJ(1)) plane with J(1) > 0 has yielded five distinct ground state configurations. The temperature dependent phase diagrams are obtained for the case with intralayer coupling constants of the two layers with ferromagnetic type J(1) and J(2) > 0, and the interlayer coupling constant of the layers with either ferromagnetic J(3) > 0 or antiferromagnetic type J(3) < 0 on the (kT/J(1), J(3)/J(1)) planes for given values of the J(2)/J(1) for various values of the coordination numbers. As a result, we have found that the model presents both second- and first-order phase transitions, therefore, tricritical points

A study of the bilayer Bethe lattice for spin-3/2 Ising model

The spin-3/2 Ising model on the bilayer Bethe lattice is studied in terms of the exact recursion relations with the intralayer bilinear interactions J(11) and J(22) of the two layers with ferromagnetic coupling and interlayer bilinear interaction J(12) between the layers with ferromagnetic or antiferromagnetic coupling. We first have obtained the ground state configurations of the model on the (J(22)/vertical bar J(11)vertical bar,J(21)q/vertical bar J(11)) planes for J(11) 0. Then the thermal behaviors of the order-parameters, the total and staggered magnetizations of the two layers and also the spin-spin correlation function between the nearest-neighbor spins of the adjacent layers, are studied to obtain the phase diagrams of the model on the (kT/J(11),J(12)/J(11)) plane for given values of J(22)/J(11) and the coordination number q. As a result, a few types of the critical temperatures of the model are obtained. (c) 2006 Elsevier B.V. All rights reserved