A new hybrid iron fluoride bipyridine with mixed valence: Fe2F5(2,2'-bipyridine)2H2O

Hydrothermal synthesis of iron fluoride compound, Fe2F5(2,2'-bipyridine)2H2O, and its characterization by single crystal X-ray diffraction is reported. The compound is found to crystallize in the triclinic space group . The monohydrate fluoroferrate of bipyridine is built up from Fe4F10N8 tetrahedron connected by eight nitrogen atoms of four 2,2'-bipyridine molecules and separated by H2O molecules. The main feature of this atomic arrangement is the coexistence of two oxidation states of iron cations and hybrid class II with 0-D dimensionality. Thermal and IR spectral analysis have been carried out for the title compound to confirm the hematite compound as residual and the presence of organic molecule , respectively. Magnetic characterization does not reveal any ferromagnetic component in the range of magnetic field from -20 kOe to 20 kOe at room temperature

Synthèse et caractérisation physico-chimique des nouveaux fluoroferrates hybrides à base de molécules organiques

Thèse présentée par Mouna Smida Yangui pour obtenir le grade de Docteur en Chimie à l’Université de Sfax.Peer reviewe

Pitch Angle Control for Variable Speed Wind Turbines

<p><strong><span lang="EN-US">Abstract.</span></strong><span lang="EN-US">Pitch control is a practical technique for power regulation above the rated wind speed it is considered as the most efficient and popular power control method. As conventional pitch control usually use PI controller, the mathematical model of the system should be known well.</span></p><p><span lang="EN-US">This paper deals with the operation and the control of the direct driven permanent magnet synchronous generator (PMSG).</span></p><p><span lang="EN-US">Different conventional strategies of pitch angle control are described and validated through simulation results under Matlab\Simulink.</span></p

Fluoroferrate templated with HAmTAZ: X-ray single crystal, thermal behaviour, vibrational study and magnetic characterization

A new metal–organic compound FeF6(HAmTAZ)3 which (HAmTAZ = 3-amino-1,2,4-triazole) was hydrothermally synthesized from an equimolar mixture of FeF2 and FeF3 with HAmTAZ, aqueous HF and ethanol solvent at 410 K yielded a new hybrid class I fluoroferrate. The structure was characterized by single-crystal X-ray diffraction data. The crystal structure of FeF6(HAmTAZ)3 crystallizes in the trigonal system space group R3c with a = b = 12.5230 (6) Å, c = 18.5950 (16) Å, γ = 120° and Z = 6. The structure was built up from isolated octahedral FeF6 separated by [HAmTAZ]+ cations. The thermal analysis has shown that the decomposition undergoes two steps between 475 and 775 K. IR and mass spectrometry have been used to confirm the presence of the organic molecule in the crystal lattice and determine the evacuated vapours during the decomposition, respectively. The magnetization of the title compound has no revealed any ferromagnetic component in the range of magnetic field from −20 to 20 KOe at room temperature.This research work is supported by the Tunisian Ministry of Higher Education and Research and the Spanish MINECO (MAT2006-150AM).Peer Reviewe

A new hybrid iron fluoride bipyridine with mixed valence: Fe2F5(2,2'-bipyridine)2H2O

810-815Hydrothermal synthesis of iron fluoride compound, Fe2F5(2,2'-bipyridine)2H2O, and its characterization by single crystal X-ray diffraction is reported. The compound is found to crystallize in the triclinic space group . The monohydrate fluoroferrate of bipyridine is built up from Fe4F10N8 tetrahedron connected by eight nitrogen atoms of four 2,2'-bipyridine molecules and separated by H2O molecules. The main feature of this atomic arrangement is the coexistence of two oxidation states of iron cations and hybrid class II with 0-D dimensionality. Thermal and IR spectral analysis have been carried out for the title compound to confirm the hematite compound as residual and the presence of organic molecule , respectively. Magnetic characterization does not reveal any ferromagnetic component in the range of magnetic field from -20 kOe to 20 kOe at room temperature

Structure, Thermal Behavior and Characterization of a New Hybrid Iron Fluoride FeF4(2,2 '-bipyridine)(H2O)(2)

New crystal of FeF4(2,2′-bipyridine)(H2O)2 was prepared by hydrothermal synthesis. Crystalline structure determination is performed from single crystal X-ray diffraction data. The unit cell is monoclinic space group P21/n, with cell parameters a=0.9046(5) nm, b=0.7502(5) nm, c=1.9539(5) nm, β=93.307(5)°, V=1.3238(12) nm3 and Z=4. The structure of FeF4(2,2′-bipyridine)(H2O)2 is built up from FeF4N2 octahedra coordinated by two nitrogen atoms of the 2,2′-bipyridine molecules, and four fluorine atoms as well as uncoordinated H2O molecules. Thermal analysis of the title compound showed that the decomposition introduced four steps. IR spectra confirmed the presence of 2,2′-bipyridine molecules. The optical absorption was measured at the corresponding λmax using UV-Vis diffuse reflectance spectrum.Supported by the Project from the Ministry of Superior Education and the Research of Tunisia and Spanish MINECO (No. MAT2006-150AM).Peer Reviewe

Hydrothermal synthesis, thermal decomposition and optical properties of Fe2F5(H2O)(Htaz)(taz)(Hdma)

Crystal structure of Fe2F5(H2O)(Htaz)(taz)(Hdma) which crystallizes in the triclinic sys-tem space group P1 with unit cell parametersa= 8.8392(5) A ̊,b= 9.1948(5) A ̊,c= 9.5877(5) A ̊,a= 82.070(3)°,b= 63.699(3)°,c= 89.202(3)°,Z= 2, andV= 690.91(7) A ̊3, was synthesizedunder hydrothermal conditions at 393 K for 72 h, by a mixture of FeF2/FeF3, 1,2,4-triazole mole-cule (Htaz), and hydrofluoric acid solution (HF 4%) in dimethylformamide solvent (DMF). Themain feature of this material is the coexistence of two oxidation states for iron atoms (Fe2+,Fe3+) in the unit cell, which associate by opposite fluorine corners of FeF5N and FeF2N4octahe-dra, and/or triazole molecule which originates the 2D produces material. The structure determina-tion, performed from single crystal X-ray diffraction data, lead to theR1/WR2reliability factors0.031/0.087. Thermal stability studies (TG/DTG/DTA) show that the decomposition provides inthe temperature range 473–773 K and no mass loss was detected before 473 K. Mass spectrometry(MS) has been used. The optical absorption of the solid was measured at the correspondingkmaxusing UV–vis diffuse-reflectance spectrum.This work was supported by the minister of superior educationand research of Tunisia and Spanish MINECO (MAT2013-40950R

Hydrothermal synthesis, thermal decomposition and optical properties of Fe2F5(H2O)(Htaz)(taz)(Hdma)

International audienc

Optimal DG Location and Sizing to Minimize Losses and Improve Voltage Profile Using Garra Rufa Optimization

Distributed generation (DG) refers to small generating plants that usually develop green energy and are located close to the load buses. Thus, reducing active as well as reactive power losses, enhancing stability and reliability, and many other benefits arise in the case of a suitable selection in terms of the location and the size of the DGs, especially in smart cities. In this work, a new nature-inspired algorithm called Garra Rufa optimization is selected to determine the optimal DG allocation. The new metaheuristic algorithm stimulates the massage fish activity during finding food using MATLAB software. In addition, three indexes which are apparently powered loss compounds and voltage profile, are considered to estimate the effectiveness of the proposed method. To validate the proposed algorithm, the IEEE 30 and 14 bus standard test systems were employed. Moreover, five cases of DGs number are tested for both standards to provide a set of complex cases. The results significantly show the high performance of the proposed method especially in highly complex cases compared to particle swarm optimization (PSO) algorithm and genetic algorithm (GA). The DG allocation, using the proposed method, reduces the active power losses of the IEEE-14 bus system up to 236.7873%, by assuming 5DGs compared to the active power losses without DG. Furthermore, the GRO increases the maximum voltage stability index of the IEEE-30 bus system by 857% in case of the 4DGs, whereas GA rises the reactive power of 5DGs to benefit the IEEE-14 bus system by 195.1%

Analyzing grid connected shaded photovoltaic systems with steady state stability and crow search MPPT control

The field of research in maximum power point tracking (MPPT) methods is making significant progress with a wide range of techniques, from simple yet inefficient approaches to more complex but effective ones. Therefore, it is important to suggest a simple and effective strategy to control the global maximum power point (GMPP) of a photovoltaic (PV) system especially under partial shading conditions (PSC). This paper proposes a novel metaheuristic MPPT called the Crow Search Algorithm (CSA) to ameliorate the tracking performance of a grid connected shaded PV system. The CSA is a nature inspired method based on the intelligent behaviors of crows in its search process for hidden food sources. This novel method succeeds to mitigate the adverse impacts of partial shading on the performance of PV systems by accurately tracking the GMPP. Based on the small-signal dynamic model, the stability of the proposed system is analyzed. Simulation results for three different levels of partial shading, including zero, weak, and severe shading, demonstrate the better performance of the suggested CSA compared to fuzzy logic controller (FLC) and Inc-Cond techniques. In fact, the comparison is carried out in terms of simplicity of implementation, high efficiency, and low power loss, decreasing considerably the convergence time