Search

This paper is based on designing a modifi ed rotor for a drivetrain in a Type-III wind turbine system for maximum power generation to work eff ectively under low and high wind speed and its variation. In this paper three drive trains are designed for the gearbox to provide regulated torque and thrust force. For time to time variation in wind speed the voltage sag and during over speed condition voltage swell problem can be solved by using this modifi ed design. The pitch control, gear box and yaw of the wind turbine basically focused for modifi cation. Mainly the gear box for the rotor causes sluggish motion of the rotor during low wind speed. This paper explained the design of modifi ed rotor control for the gear box in DFIG based (Type-III) wind turbine. Also in this paper how the modifi ed rotor system can be helpful for reactive power control highlighted with comparison with existing models. For designing MATLAB Simulink platform is taken and validated using CFD mechanical design analysis. Using these types of modifi ed drive trains maximum power for the wind turbines is enhanced by 40–60% of its reference value. [ABSTRACT FROM AUTHOR]

Economic dispatch has a significant effect on optimal economical operation in the power systems in industrial revolution 4.0 in terms of considerable savings in revenue. Various non-linearity are added to make the fossil fuel-based power systemsmore practical. In order to achieve an accurate economical schedule, valve point loading effect, ramp rate constraints, and prohibited operating zones are being considered for realistic scenarios. In this paper, an improved, and modified version of conventional particle swarm optimization (PSO), called Oscillatory PSO (OPSO), is devised to provide a cheaper schedule with optimum cost. The conventional PSO is improved by deriving a mechanism enabling the particle towards the trajectories of oscillatory motion to acquire the entire search space. A set of differential equations is implemented to expose the condition for trajectory motion in oscillation. Using adaptive inertia weights, this OPSO method provides an optimized cost of generation as compared to the conventional particle swarm optimization and other new meta-heuristic approaches. [ABSTRACT FROM AUTHOR]

This paper highlights the study and implementation of various types of Fuzzy structures using rule based interfaces for steady state and transient analysis with Hardware in Loop validation. A mathematical modeling of Type III DFIG based modified wind turbine is designed to develop maximum efficiency during faults. The modified wind turbine is controlled by various controller s illustrated in this chapter. The Mode 1 and Mode 2 are basic controllers rather the mode 3 and mode 4 are proposed controllers using derivative and integral control to active power with PI and Fuzzy logic to reactive power. This control enhance the transient stability of the wind d turbine system. The active and reactive power can be controlled and faster response can be achieved under fault conditions. All the mode results are discussed and a comparison with proposed technique is highlighted in this work. The model is designed using MATLAB simulink and the case studies are explained by taking different wind speeds and fault conditions. The model is validated using TYPHOON hardware in Loop Real Time software to get comparative results. [ABSTRACT FROM AUTHOR]

Although atomically precise polyhydrido copper nanoclusters are of prime interest for a variety of applications, they have so far remained scarce. Herein, this work describes the synthesis of a dithiophosphate‐protected copper(I) hydride‐rich nanocluster (NC), [Cu30H18{S2P(OnPr)2}12] (1H), fully characterized by various spectroscopic methods and single‐crystal X‐ray diffraction. The X‐ray structure of 1H reveals an unprecedented central Cu12 hollow icosahedron. Six faces of this icosahedron are capped by Cu3 triangles, the whole Cu30 core being wrapped by twelve dithiophosphate ligands and the whole cluster has ideal S6 symmetry. The locations of the 18 hydrides in 1H were ascertained by a single‐crystal neutron diffraction study. They are composed of three types: capping μ3‐H, interstitial μ4‐H (seesaw) and μ5‐H ligands (square pyramidal), in good agreement with the DFT simulations. The numbers of hydrides and ligand resonances in the 1H NMR spectrum of 1H are in line with their coordination environment in the solid state, retaining the S6 symmetry in solution. Furthermore, two new Se‐protected polyhydrido copper nanoclusters, [Cu30H18{Se2P(OR)2}12] (2H: R=iPr 3H: R=iBu) were synthesized from their sulfur relative 1H via ligand displacement reaction and their X‐ray structures feature the exceptional case where both the NC shape and size are fully conserved during the course of ligand exchange. DFT and TD‐DFT calculations allow understanding the bonding and optical properties of clusters 1H–3H. In addition, the reaction of 1H with [Pd(PPh3)2Cl2] in the presence of terminal alkynes led to the formation of new bimetallic Cu−Pd alloy clusters [PdCu14H2{S2P(OnPr)2}6(C≡CR)6] (4: R=Ph; 5: R=C6H4F). [ABSTRACT FROM AUTHOR]

When a Double Fed Induction Generator (DFIG) primarily based Type-III Wind Turbine (WT) is connected to the grid without a digital power interface, the terminal voltage or reactive electricity output can't be managed accordingly. Many techniques have been developed to overcome the issue of low voltage due to faults. This paper tries to define such active methods by presenting a complete analysis of LVRT strategies for DFIG-based Wind Energy Conversion Systems (WECS) in terms of overall adaptive performance, operation complexity of controllers, and cost-effectiveness. This paper aims to highlight the methods of increasing the ability of LVRT relying on the configuration of the relationship into 3 major areas according to its grid integrations. Shunt connections of FACTS devices are used in WECS to study their effectiveness and benefits. The system models are simulated in MATLAB/Simulink and the results are discussed. [ABSTRACT FROM AUTHOR]

A single-phase lead-free ferroelectric compound, Fe 1 / 2 (NaLi) 1 / 4 TiO3, is found at room temperature. The solid state reaction technique helps to process the sample at the calcination and sintering temperatures of 900 and 950 ∘ C for 4 h respectively. The desired phase and crystal structure formation of the prepared sample are confirmed by analysis of X-ray diffraction (XRD) data and are found to be in orthorhombic structure. The correlation among phase formation and physical properties has been established by using complex impedance spectroscopy (CIS) method over a wide range of frequencies (from 100 Hz to 1 MHz) and different temperatures (25–280 ∘ C). The overlap depressed semicircular arcs represent the association of grain and grain boundary effects in the material. Activation energy (E a) is noted to be 1 eV for the prepared sample. The frequency dependent ac conductivity is followed by Jonscher's universal power law. DC conductivity versus temperature graph also indicates the negative temperature coefficient of resistance (NTCR) behavior of the material. [ABSTRACT FROM AUTHOR]

The strontium-modified barium titanate ( Ba 0. 7 Sr 0. 3 TiO 3) ceramic was fabricated by high temperature compound reaction route. The pattern of X-ray diffraction confirms a single-phase compound with better crystallization. The dielectric properties (permittivity/loss) are investigated as a function of temperature and frequency. The relaxation mechanism and correlation with the physical properties are studied using complex impedance spectroscopy. The Nyquist plot shows the association of various effects (grain and grain boundary) by fitting electrical circuits at various temperature regions. This study tells the nature and conduction mechanism of the prepared sample. The Jonscher's universal power law is being followed by the frequency-dependent ac conductivity. [ABSTRACT FROM AUTHOR]

A structural study of ligand exchange on chalcogen‐passivated copper nanoclusters is far less developed. Herein, we report the synthesis of polyhydrido copper nanoclusters [Cu20H11{Se2P(OiBu)2}9] (2) passivated by Se‐donor ligands via ligand replacement reaction on [Cu20H11{S2P(OiPr)2}9] (1) with NH4[Se2P(OiBu)2]. In parallel to the synthesis of 2, cluster [Cu20H11{S2P(CH2CH2Ph)2}9] (4) was produced by the ligand exchange reaction on a new derivative of 1, that is [Cu20H11{S2P(OnPr)2}9] (3). Solid state structures of both clusters 2 and 4 were unequivocally established by single‐crystal X‐ray diffraction studies and cluster 4 epitomizes exceptional case to preserve both the shape and size of the nanocluster during the course of ligand exchange. Structurally precise cluster 2 is the second example where the copper hydride nanocluster is stabilized by Se‐donor ligands. The anatomy of 2 can be visualized as a twisted cuboctahedral Cu13 core, two triangular faces of which are capped by a Cu6 cupola and a single Cu atom along the C3 rotational axis. [ABSTRACT FROM AUTHOR]

Relaxation mechanism, conductivity and magnetoelectric properties of (Nd1/2Li1/2)(Fe2/3Mo1/3)O3 multiferroic have been investigated systematically. This material was synthesized by a solid-state reaction route. Thermogravimetric analysis is enforced to perceive the percentage of weight change with rise in temperature in order to obtain the calcination temperature of the material. The preliminary structural study using X-ray diffraction data reveals the orthorhombic structure of the material. The complex plot of impedance data helped to distinguish the involvement of grain as well as grain boundary effects towards the overall electrical properties of the compound. Temperature-dependent electrical conductivity plots exhibit the presence of thermally activated conduction mechanism of the compound. The magnetic field dependence of magnetization (M–H loop) showed the presence of ferromagnetic nature of the material. The value of magnetoelectric coupling coefficient of prepared material is found to be 2.7 mV Cm−1 Oe−1. [ABSTRACT FROM AUTHOR]

Shape-memory polymers (SMPs) are stimuli-responsive shape-varying polymers. Now a days they become a great interest for fundamental research and technological innovation. Here a brief review of the recent trends in the arena of SMPs is presented with particular focus on their structure, shape-memory effects and practical application. A special attention is given to smart multi-responsive and multi-functional advanced SMP materials as they are of emerging technological class. Important applications of SMP in the field of biomedical engineering, polymer domain, and material replacement are explained in the applications part. Traditional shape memory polymers (SMPs) are those which are capable of memorizing a temporary shape and recovering to the initial shape upon heating. Though SMP is old concept initiated half a century ago but its applications in variety of fields is the topic where it’s lagging. As such, the intent of the present paper isn’t to supply an intensive review of the SMP analysis. Instead, the main focus is on light samples of recently emerged from memory phenomena, their thoughtful impact to the sector of SMP on each scientific and sensible fronts, and future outlook. [ABSTRACT FROM AUTHOR]

In the present communication, studies of some physical properties (i.e., crystal data, permittivity, impedance, electrical cobnduction and magnetic) of a multiferroic material with a chemical composition (SmLi)1/2(Fe2/3Mo1/3)O3 have been reported. Thermogravimetric analysis of the compound, prepared by cost effective ceramic technology processing, was executed to check the mass loss as well as the required decomposition temperature of the ingredients. An analysis of X-ray spectra or pattern suggests that the crystallization phase or cystal system of the compound at room temperature is orthorhombic. The broad studies of dielectric properties {relative dielectric constant (εr), and tangent loss (tan δ)} display their independence of temperature and frequency in the rage of (30-375 °C) and (1 kHz-1 MHz) respectively. The impedance spectroscopic technique has provided a considerable significant information regarding the grain, grain boundary contribution within the sample and relaxation mechanism of the compound. The occurrence of negative temperature coefficient behaviour (NTCR) is depicted by the further analysis of impedance parameters. The frequency-temperature dependence of conductivity follows the Johnson’s power Universal law. The Arrhenius plot (i.e., variation of electrical conductivity with temperature) is used to calculate the activation energy. Analysis of magnetization (M-H) loop shows weak ferromagnetism of the compound. The material possesses significantly high magnitude of magnetoelectric coefficient of 3.0 mV Cm− 1 Oe− 1. [ABSTRACT FROM AUTHOR]

Building upon our earlier studies of cobaltaheteroboranes, we explore the chemistry with heavier group 9 metals. Reaction of [Cp*M(µ‐Cl)Clx]2 (Cp* = η5‐C5Me5; M = Co, x = 0; M = Rh or Ir, x = 1) with [LiBH4·THF], followed by thermolysis with an excess of chalcogen powders (S or Se), affords dimetallaheteroboranes nido‐[(Cp*M)2B2H2E2], 1–4 (1: E = S; 2: E = Se, M = Co; 3 and 4: E = Se, M = Rh and Ir, respectively) in moderate‐to‐good yields. The solid‐state structures of these compounds show open‐cage triple‐decker clusters. Attempts to isolate the Te analogue have failed; however, in the case of cobalt, we have isolated an 11 skeletal‐electron‐pair nido‐[(Cp*Co)2B5H5Te2], 5. The X‐ray diffraction structure of 5 shows monocapped square antiprismatic geometry, with two Te atoms in the core. To close the central four‐membered B2E2 open ring of nido‐1 and nido‐2, we have performed a reaction with [Ru3(CO)12], which leads to the formation of closo‐[(Cp*Co){µ‐η5:η5‐B2H2E2M}M{µ‐Ru(CO)4}], 6 and 7 [6: E = S; 7: E = Se; M = Ru(CO)2]. In contrast, the reactions of nido‐2 and nido‐3 with [Fe2(CO)9] result in heterometallic clusters nido‐[(Cp*M)Fe(CO)3B2H2Se2], 8 and 9 (8: M = Co; 9: M = Rh), [(Cp*Co)Fe3(CO)8Se2], 10, and [(Cp*Co)Fe2(CO)7Se], 11. As nido‐8 also contains a four‐membered open ring B2Se2, we have treated this with [Ru3(CO)12], which yields closo‐[(Cp*Co){µ‐η5:η5‐B2H2Se2M}M{µ‐Fe(CO)4}], 12 [M = Ru(CO)2], which is analogous to that of 7. In addition, we have analyzed the divergence in the reactivity of nido‐[(Cp*M)2B2H2E2], 2–4, with the help of density functional theory calculations. [ABSTRACT FROM AUTHOR]

Several early-late heterodimetallaborane clusters have been isolated and structurally characterized through spectroscopic and crystallographic analysis. The thermolysis of [Cp2Zr(BH4)2] (Cp = η5-C5H5) with [Cp*IrB3H9] (Cp* = η5-C5Me5) and [(Cp*Rh)2B2H6] yielded arachno-[(Cp2Zr)(Cp*Ir)B3H9] ( 2) and arachno-[(Cp2Zr)(Cp*Rh)B4H10] ( 4), respectively. In a similar fashion, the reaction of [Cp2Hf(BH4)2] was performed with the same set of group 9 metallaboranes that led to the formation of arachno-[(Cp2Hf)(Cp*M′)B4H10] ( 5: M′ = Ir; 6: M′ = Rh). To the best of our knowledge, 2 is the first structurally characterized pentaborane(11) analogue containing zirconium, while the clusters 5 and 6 are the first examples with Hf in a hexaborane(12) core. The bonding between the Zr atoms and the boron ring was studied computationally by DFT methods, and 2 can be defined as a dimetallic analogue of arachno-B5H11 on the basis of the combined experimental and computational results. [ABSTRACT FROM AUTHOR]

A single phase multiferroic magnetoelectric compound, (Sm 0.5 Li 0.5 )(Fe 0.5 V 0.5 )O 3 , is found at room temperature. This sample is fabricated using solid state reaction route. Analysis of the structural properties of the sample by X-ray diffraction method confirmed the fabrication of the desired compound with orthorhombic unit cell structure. Morphological property of the sample is recorded by field emission scanning electron microscopy (FE-SEM). Impedance spectroscopy is employed to determine the various electrical parameters such as dielectric constant, loss tangent, impedance, electric modulus, etc. at different temperature (RT–400 °C) within a frequency range of (1 kHz–1 MHz). Furthermore, the bulk resistance as function of temperature and J – E characteristic showed the semiconducting behavior of sample with negative temperature coefficient of resistance (NTCR) type nature of the compound. The M – H loop of this sample indicates the ferromagnetic nature with very low coercive field. A dedicated magnetoelectric set up is used to measure the ME coefficient as a function of magnetic field and found a significant ME coefficient of 2.99 mV Cm −1  Oe −1 at room temperature. [ABSTRACT FROM AUTHOR]

The syntheses and structural characterization of the CS2-metal complexes [(η5-C5Me5M)(η2-S2CH2)(η3-S2CH)] ( 1: M = Mo; 2: M = W), which feature partially and fully reduced CS2, are reported. In addition, the cis and trans isomers of the dimetallic (sulfido)molybdenum complexes [(η5-C5Me5Mo)2(µ-S2CH2S)2] ( 3- cis and 4- trans) are described. The [Mo2S4] cores of 3- cis and 4- trans represent paddlewheel-like arrays. All the new compounds were characterized in solution by mass spectrometry, IR spectroscopy, and 1H and 13C NMR spectroscopy. Their structural architectures were established by X-ray crystallographic analysis. Quantum-chemical calculations by DFT methods on the model compounds 1′- 4′- trans showed good agreement with the experimentally observed structural parameters. The large HOMO-LUMO (HOMO = highest occupied molecular orbital, LUMO = lowest unoccupied molecular orbital) gaps are consistent with the high thermodynamic stabilities of these complexes. Further, the presence of short metal-metal cross-cluster bonds in the X-ray structures of 3- cis and 4- trans is supported by natural bond order (NBO) calculations. [ABSTRACT FROM AUTHOR]

Treatment of [Cp*IrCl2]2 (Cp* = pentamethylcyclopentadienyl) with Li[BH3(SePh)] at room temperature led to the isolation of a dimetala analogue of hexaborane(10), nido-[(Cp*Ir)(µ-SePh)2Ir{(Cp*Ir)SePh}B4H8] ( 1). Solid-state X-ray structure analysis of 1 showed an extended sandwich molecule with two iridium atoms between Cp* and a [B4Ir] ring. Further, in an effort to synthesize the Rh analogue of 1 under similar reaction conditions, we isolated arachno-[{(Cp*Rh)(µ-SePh)3}Rh(µ-SePh)B3H6] ( 2), a rhodium analogue of tetraboarane(10) in which the {RhB3} unit shows geometric equivalence with a metal π-allyl {MC3} species. Ir complex 1, having an Ir-Ir bond, can be considered similar to the dizinc sandwich complex [Cp*Zn-ZnCp*] in terms of the valence electron count at the metal centers. [ABSTRACT FROM AUTHOR]

A combined experimental and quantum-chemical study of a series of homometallic metallaheteroboranes [(Cp*M)2-E6B2H2] (M = Rh or RuH; E = S or Se; Cp* = η5-C5Me5), which are analogues of 1,3-bishomocubane, is reported. The thermolysis of nido-[(Cp*Rh)2B3H7] (1) in the presence of S or Se powder in toluene yielded bishomocubane clusters [(Cp*Rh)2-(μ-E)2(μ3-E)4B2H2], (3: E = S; 4: E = Se). In a similar fashion, the treatment of nido-[(Cp*RuH)2B3H7] (2) with S or Se powder in p-xylene yielded [(Cp*Ru)2(μ-E)2(μ3-E)4B2H2] (5: E = S; 6: E = Se) and [(Cp*Ru)2(μ3-Se)(μ4-Se)B3H5] (7). One of the noteworthy features of 3-6 is the presence of an electronprecise trichalcogenoborato ligand. All of the compounds have been characterized by mass spectrometry; IR spectroscopy; and 1H, 11B, and 13C NMR spectroscopy. The structures of 3, 4, 6, and 7 were established unequivocally by Xray crystallographic analysis. Quantum-chemical calculations by DFT methods for 3, 4, and 6 showed reasonable agreement with the experimentally observed structural parameters. The large HOMO-LUMO gaps are consistent with the high stabilities of these complexes. [ABSTRACT FROM AUTHOR]

Reaction of [(η5-C5Me5)CoCl]2 with a two-fold excess of [LiBH4·thf] followed by heating with an excess of Se powder produces the dicobaltaselenaborane species [{(η5-C5Me5)Co}2B2H2Se2], 1, in good yield. The geometry of 1 resembles a nido pentagonal [Co2B2Se2] bipyramid with a missing equatorial vertex. It can alternatively be seen as an open cage triple-decker cluster. Isolation of 1 permits its reaction with [Fe2(CO)9] to give heterometallic diselenametallaborane [{(η5-C5Me5)Co}Fe(CO)3B2H2Se2], 2. The geometry of 2 is similar to that of 1 with one of the [(η5-C5Me5)Co] groups replaced by the isolobal, two-electron fragment [Fe(CO)3]. Both new compounds have been characterized by mass spectrometry, and by 1H, 11B and 13C NMR spectroscopy. The structural architectures have been unequivocally established by crystallographic analysis. In addition, density functional theory calculations were performed to investigate the bonding and electronic properties. The large HOMO–LUMO gaps computed for both clusters are consistent with their thermodynamic stability. Natural bond order calculations predict the absence of metal–metal bonding interaction. [ABSTRACT FROM AUTHOR]

Synthesis and characterization of lithium and molybdenum modified antimony ferrite (SbLi) 1/2 (Fe 2/3 Mo 1/3 )O 3 were carried out using solid-state reaction techniques. The preparation conditions and mass loss of the homogeneous mixture of required ingredients were decided based on thermal analysis (TGA). The formation of single-phase compound was confirmed by preliminary structural analysis using X-ray diffraction data. Electric properties of the material were studied in a wide temperature range (30–500 °C) at different frequencies (100 Hz–1 MHz) using impedance spectroscopy technique. The dc conductivity was found to obey Arrhenius relation suggesting the material to be of NTCR type. The activation energy calculated from the dc conductivity curve for grain and grain boundary effect is 0.60 and 0.47 eV respectively. The Jonscher’s universal power law governs the nature of ac conductivity of the material. Remnant polarization was found to be 0.86 (μC/cm 2 ). The magnetic measurements revealed weak remnant magnetization (0.01516 emu/g). [ABSTRACT FROM AUTHOR]

Theregioselective 1,3-dipolar cycloaddition reaction of alkoxyalkynyl Fischer carbene complex 1with azidomethyl ferrocene 2and with azidomethyl pyrene 4under solvent-freeconditions yielded the triazolyl Fischer carbene complexes 3(C27H21O6N3FeW) and 5(C33H21O6N3W),respectively. The cation complexation properties of these receptorshave been systematically studied using electrochemical and spectroscopictechniques. The exceptional structural feature existing in these receptorsis the presence of a Fischer carbene moiety, connected to the ferroceneor pyrene moiety through a 1,2,3-triazole ring. Receptor 3contains a redox-active ferrocene moiety and is highly selectivetoward Pb2+ion, whereas receptor 5, havinga fluorescent pyrene unit, selectively recognizes Zn2+andCu2+ions. The binding ability of receptor 3can be inferred either from the redox shift (the anodic shift ΔE1/2= 55 mV) or the highly visual output responsefor Pb2+ion. Receptor 5displays considerablechelation-enhanced fluorescence (CHEF) upon binding with Zn2+and Cu2+ions in an aqueous environment. Further, theproposed binding modes of these receptors and their metal cation complexationproperties have been supported by 1H NMR titration andMALDI-MS and a DFT study. [ABSTRACT FROM AUTHOR]

The photolysis of [M2(CO)10] (M=Re or Mn) with BH3⋅thf at room temperature yields arachno -1 and 2, [(CO)8M2B2H6] ( 1: M =Re, 2: M =Mn). Both the compounds show a butterfly structure with seven skeletal electron pairs and 42 valence electrons. This result presents a new method for general access to low-boron-content metal-boron compounds without the cyclopentadienyl ligand at the metal centers. This new synthetic route is superior to the existing procedures because it avoids the use of [LiBH4] and metal polychlorides, for which the synthesis is very tedious. Compound 1 catalyzes the cyclotrimerization of a series of internal and terminal alkynes to yield mixtures of 1,3,5- and 1,2,4-substituted benzenes. The reactivity of 1 with alkynes demonstrates for the first time that the introduction of the [B2H6] moiety into the [Re2(CO)10] framework significantly enhances the catalytic activity. Note that [Re2(CO)10] catalyzes the same set of alkynes under harsh conditions over a prolonged period of time. Quantum-chemical calculations using DFT methods are applied to afford further insight into the electronic structure, stability, and bonding of 1 and 2. All the compounds are characterized by IR and 1H, 11B, and 13C NMR spectroscopy, and the geometry of 1 is established unambiguously through crystallographic analysis. [ABSTRACT FROM AUTHOR]