Windmill Structure Research Articles

Distinguishing the topological charge of vortex beam via Fourier back plane imaging with chiral windmill structure

In recent years, research on the interaction between orbital angular momentum (OAM) of light and matter has shown a continuous influx of investigations. OAM possesses distinct properties, such as a degree of freedom with multiple states, vortex characteristics, and topological properties, which expand its applications in optical communication, optical sensing, and optical manipulation. We have observed different phenomena in the chiral metal windmill structure under excitation of spin angular momentum (SAM)-OAM beam generated by Q-plate than under SAM excitation. Fourier back focal plane (FBP) imaging under SAM beam excitation easily identifies the chirality and geometric properties of the structure. When the SAM-OAM beam excites the structure, FBP not only identifies its chirality and geometric properties but also distinguishes different OAM topological charges and signs, as well as the degree of elliptic polarization. The Stokes parametric FBP imaging reveals asymmetric polarization distribution resulting from the interaction between a vortex beam and the chiral structure. Moreover, it clearly reflects the conversion process of SAM to OAM. The experimental results match well with simulation results. These findings hold valuable insights for the advancement of optical information storage and communication using OAM, opening up new possibilities for further exploration in this field.

Propagation characteristics of twisted cosine-Gaussian Schell-model beams

We introduce a new class of twisted sources with twisted cosine-Gaussian Schell-model correlation structure. The spectral intensity and the degree of coherence of the field upon propagation are discussed. Such novel twisted field is characterized by unfamiliar twist pattern and controllable far-zone lattice profile. It exhibits a Gaussian or a lattice-like intensity distribution in the source plane, while always turns into a 2×2 lattice profile in the far zone. Notably, the array profile twists around the propagation axis instead of each element rotating about its own lobe center, which is different from most of the twisted array models. Moreover, the splitting tendency in the intensity distribution could be flexibly modulated by the twisted factor, the source coherence and the beam width. The coherence distribution could rotate in the same direction as the intensity with appropriate choice of parameters. Finally, the cross-spectral density’s phase distribution exhibits a spiral windmill structure and coherent singularities could be observed upon propagation.

Windmill discharge migration pattern during plasma electrolytic oxidation of aluminium

Plasma electrolytic oxidation process is a surface modification technique using plasma-assisted oxidation to prepare the protective layers that improve the surface performances of valve metals such as aluminium, magnesium, and titanium. However, there is poor understanding and ability to control the process, and many uncertainties. The main objective of this paper is to present the discharge behavior with windmill structure, stable group movement and long-term stability. All processes were carried out on 6061 aluminium alloy by applying a bipolar pulsed current with a frequency of 200 Hz, positive and negative pulse durations of 2 ms, and equal pulse pauses. Utilizing current pulses having equal amplitudes between the positive and negative periods resulted in destructive discharges in the late stage. By adjusting the average positive current at a certain time, destructive discharges were eliminated. Meanwhile, various windmill discharge migration patterns were established, in which collective discharges aggregated into several clusters and rotated as a whole on the sample surface. The number of the clusters was correlated to the average positive current. A complete plasma electrolytic oxidation process was proposed to produce a series of coatings, in which the average positive current was reduced at a rate of 0.1 A·min−1 from 95 min to 100 min, and the windmill discharge migration pattern gradually emerged after 100 min. The proposed method increased the treatment duration from ~95 min to ~180 min compared to the process with no current adjustment. In addition, the thickness, relative content of α- and γ-Al2O3 phases, and Vickers hardness of the coatings were significantly enhanced, allowing for the preparation of high-quality coatings.

Equivalent Circuit Analysis of Metamaterial Structure

In this paper, an equivalent circuit model of swastika-like structure metamaterial is investigated. Mutual inductance between adjacent swastikas ring arrays is taken into consideration in the proposed equivalent circuit model. The analytical expression for calculating the effective permeability of the windmill structure is derived. By the derived expressions, the physical mechanisms of the magnetic resonance frequency versus structural parameters are well explained. Based on the equivalent circuit model, some strategies for the fast and efficient optimization metamaterial structures can be used to achieve a better target performance in the future.

ANSYS-based Force Analysis on a New Horizontal Axis Wind Turbine Shield

The importance of renewable energy sources cannot be denied in the era of increase of greenhouse gas emission and depletion of fossil fuels. The wind energy and design of new yet effective windmills become a necessity nowadays. This paper introduces a new configuration of wind turbine with a horizontal axis and ANSYS-based dynamic analysis of its high-speed protection shield that protects the turbine from overspending at extreme wind conditions. In comparison to traditional horizontal wind turbine structure, HAWT blades have a flat shape, and they are exposed to wind stream in such a way that the wind forces are strictly perpendicular to the blade surfaces. This structure extracts more wind energy and minimizes the useless forces affecting shaft joints in traditional wind turbines. The ANSYS-based force analysis presented in this paper proves the advantage of using of protection shield in such windmill structure.

Implementation Of Wind Mill Monitoring System Using IoT and Wi-Fi – Through Gsm Protocol

This endeavor presents examinations of using remote sensor frameworks for checking conditions inside wind farms, taking into considerations the specific of such applications. In these circumstances, which are wanted to gain a lot of ground or even work in inconvenient radio conditions with strong diminishing, the fundamental and direct correspondence among source and objective isn't continually possible, due to the partition repression. To beat these facts, we propose a system which continually screens the parameters of the windmill structure and transmits those data's to the cloud using IOT.This system discards the Range force for passing these parameters to the checking structure. [19],[20],[21]

Self-Assembly and Electronic Structure of Tribenzotriquinacenes on Ag(111)

The structure of two-dimensional layers of organic compounds on metal surfaces is of great interest for the fabrication of devices in the field of organic electronics. To progress in this area, a deeper understanding of intermolecular interactions and charge transfer processes between organic molecules and a metal substrate is required. Here, the two-dimensional self-assembly of tribenzotriquinacenes (TBTQs) on Ag(111) was studied by scanning tunneling microscopy under ultrahigh vacuum conditions. Highly ordered monolayers of tribenzotriquinacene (TBTQ) and centro-methyl tribenzotriquinacene (Me-TBTQ) were observed for the first time. At low to moderate coverage, both of these bowl-shaped molecules adsorb with the bowl opening faced downward, appearing in two orientations that are rotated by 14° from the high-symmetry axis of the Ag(111) surface. At high TBTQ coverage, extended islands with a self-assembled highly ordered windmill nanostructure dominate the surface, interspaced with nanometer-sized openings. This windmill structure is absent in Me-TBTQ, which immediately forms double-layered regions at high coverage. Scanning tunneling spectroscopy measurements, which probe the local density of states, identify a shift of the Ag(111) surface state in the presence of the TBTQ molecules. Investigations such as these into the self-assembly of curved aromatics provide a foundation for further work on the construction of multilayer nanostructures and the production of electronic devices.

An electromagnetic energy harvesting device based on high efficiency windmill structure for wireless forest fire monitoring application

In this paper, we introduce a miniature windmill-structured energy harvester for wireless monitoring of forest fires. The proposed energy harvester design can effectively scavenge the energy from ambient air flow using electromagnetism, thereby self-powering the wireless sensing nodes for fire alarming. To find an optimal structure with the highest aerodynamic efficiency and sensitivity to wind flow, miniature energy harvesters with various windmill structures were designed, simulated, 3D printed and experimentally characterized. In the performance test, with the optimized windmill structure, a peak output voltage of 5.2V and a peak output power of 60mW were achieved by the energy harvester with a load resistance of 150Ω. Moreover, a wireless transmission module was designed and connected to the windmill-structured energy harvester to constitute a wireless fire monitoring system. This module successfully transmitted an alarm signal upon detection of a fire in the feasibility test.

Parameter retrieval of chiral metamaterials based on the causality principle

The parameter retrieval method based on the causality principle and Kramers- Kronig relations, which has been proposed for extracting effective parameters of metamateri- als (MTMs) is extended to extract effective parameters of chiral metamaterials (CMMs) as well. Using Kramers-Kroning relations, the branch selecting problem which is the challenge of effective media parameters retrieval methods could be simply removed. To demonstrate the validity of the method, first, the constitutive parameters of a homogeneous chiral media are retrieved in the excellent agreement with the supposed parameters. Second validation is achieved by extracting the effective parameters of two well-known CMM structures whose effective parameters have been reported in the literature. The results are in excellent agree- ment with the reports of the previous works. Finally, a new type of CMMs called windmill structure is suggested, and its effective parameters are then extracted using the proposed method. V C 2012 Wiley Periodicals, Inc. Int J RF and Microwave CAE 00:000-000, 2012.

Wind load modeling for topology optimization of continuum structures

Topology optimization of two and three dimensional structures subject to dead and wind loading is considered. The wind loading is introduced into the formulation by using standard expressions for the drag force, and a strategy is devised so that wind pressure is ignored where there is no surface obstructing the wind. A minimum compliance design formulation is constructed subject to a volume constraint using the Solid Isotropic Material with Penalization model. The optimization problem is solved using the Method of Moving Asymptotes, modified by including a line search and by changing the formula for the update of asymptotes. To obtain black/white design, intermediate density values, which are used as design variables, are controlled by imposing an explicit constraint. Numerical examples of a windmill structure demonstrate that the proposed formulation rationally incorporates the effect of wind loading into the topology optimization problem as illustrated by void appearing in the optimal structure.

Design and Development of a Fibre Composite Windmill Structure

This paper presents the case study of designing the University of Southern Queensland windmill fibre composite tower — from developing the structural concept, and showing the importance of the early coordination between the design and manufacturing. With the main structural system based on sandwich construction, its behavioural issues and failure modes are discussed. As there is no design codes or guidelines that can be located in the literature, engineering judgement, understanding of the basic modes of failure, and the manufacturing limitations and tolerances are essential in developing the appropriate design. The finite element modelling considerations and their complementary experimental results are presented. The paper concludes with general discussion of using composites for the main structural elements.

Coverage dependent structures of oligopyridine adlayers on (111) oriented Ag films

The coverage dependent formation of ordered structures in vapor deposited 2,4'-bis(terpyridine)derivatives (2,4'-BTP) on (111) oriented Ag films was investigated by STM. Following a two-dimensional (2D) disordered gas phase at lowest coverages, a sequence of at least three ordered structures is observed with increasing coverage. These include a 'parallel chain structure' (PCS), a 'quasi-quadratic network' (QQN) structure, and a 'packed windmill structure' (PWS), with ideal coverages of 0.37, 0.4, and 0.44 molecules nm(-2). At intermediate coverages between 0.37 and 0.44 molecules nm(-2), these structures coexist in larger islands. The energetics of the different phases, whose structures are mainly determined by attractive C-H[dot dot dot]N bridges, are discussed in a picture including C-H[dot dot dot]N and C-H[dot dot dot]H-C interactions and lateral variations in the substrate-adsorbate interactions.

Alkali-metal-controlled self-assembly of crown-shaped ring complexes of lanthanide/[alpha-AsW9O33]9-: [K subset [Eu(H2O)2(alpha-AsW9O33)]6]35- and [Cs subset [Eu(H2O)2(alpha-AsW9O33)]4]23-.

Crowning glory: The L-shaped [Ln(H2O)2(α-AsW9O33)]6− (Ln=lanthanide) building unit provides an elegant approach to develop crown-shaped structures of [{Ln(H2O)2(α-AsW9O33)}n]6n− (n=even number of ≥4) which can encapsulate a cation. The watermill-propeller structure, left, is a K+ ion encapsulated by six [α-AsW9O33]9− ligands, whereas the windmill structure, right, is a Cs+ ion encapsulated by four [α-AsW9O33]9− ligands.

Two-state Conformational Changes in Inositol 1,4,5-Trisphosphate Receptor Regulated by Calcium

Inositol 1,4,5-trisphosphate receptor (IP3R) is a highly controlled calcium (Ca2+) channel gated by inositol 1,4,5-trisphosphate (IP3). Multiple regulators modulate IP3-triggered pore opening by binding to discrete allosteric sites within IP3R. Accordingly we have postulated that these regulators structurally control ligand gating behavior; however, no structural evidence has been available. Here we show that Ca2+, the most pivotal regulator, induced marked structural changes in the tetrameric IP3R purified from mouse cerebella. Electron microscopy of the IP3R particles revealed two distinct structures with 4-fold symmetry: a windmill structure and a square structure. Ca2+ reversibly promoted a transition from the square to the windmill with relocations of four peripheral IP3-binding domains, assigned by binding to heparin-gold. Ca2+-dependent susceptibilities to limited digestion strongly support the notion that these alterations exist. Thus, Ca2+ appeared to regulate IP3 gating activity through the rearrangement of functional domains.