Annular Elements Research Articles

A new fast simulation method of wind turbine wake based on annular vortex element

A fast simulation method of wind turbine wake field based on the combination of lifting line and annular vortex elements is proposed to simulate the bound circulation on the blade by means of lifting line, and to simulate the evolution of the wake field by releasing the annular vortex elements through the blade. The method can be iterated until convergence is sufficient by distributing the vortex elements basin-wide through periodicity in the initialization stage. The accuracy and applicability conditions of the method are verified by comparing the above method with wind tunnel tests and software simulation results using different methods. The method is clear and simple, with low computational cost and high computational accuracy.

Highly-accurate and non-invasive flowrate monitoring for miniature pipelines using piezoelectric micromachined ultrasonic transducers

Noninvasive and real-time flowrate measurement for small pipes is crucial in medical diagnostics and aviation hydraulic system health monitoring. However, current bulk PZT-based ultrasonic flowmeters are unsuitable for these scenarios due to their large size, high power consumption, and poor integration with ICs. This paper proposes a highly accurate and universal ultrasonic flowrate measurement technique for pipes with small diameters (≤ 15 mm) using piezoelectric micromachined ultrasonic transducers (PMUTs) by taking advantage of their miniaturized size, low power consumption, and superior integration capability. A clamp-on testing method is proposed for ultrasound transmitting and receiving. The inside liquid flowrate is measured based on the propagation time difference between the upstream and downstream ultrasound waves. To enhance accuracy, a unique PMUTs chip with a center circular element and an outer annular element is developed to improve acoustic pressure. Additionally, the incident angle and working frequency of ultrasound waves are optimized to reduce the interference caused by ultrasound wave superposition at the PMUTs and pipe wall interface. This optimization also improves acoustic energy transmission and response. The flowrate of water in a steel pipe is successfully measured, demonstrating excellent linearity (99.69%) between flowrate and time difference, with a high accuracy of 2%. Furthermore, flowrate testing for pipes with different diameters and pipe wall materials is experimentally demonstrated, showing widespread usability. The developed PMUTs-based flowmeter is versatile and compatible with common pipes, allowing compact integration in tight spaces, making it highly promising for practical applications.

SAFE PERFORMANCE OF WORKS IN CONSTRUCTION AND HOUSING AND COMMUNAL SERVICES USING THE ORIGINAL SCAFFOLDING DESIGN

Our development relates to construction, namely scaffolding and scaffolding used when working at height. It is intended for fencing the work area when carrying out various types of work, for example, when performing brickwork from scaffolding. In construction, where safety and efficiency play a crucial role, the correct selection and use of scaffolding are integral to every successful project. We have proposed a patent-protected solution. It is a scaffolding railing consisting of vertical support posts hinged with horizontal crossbars, characterised by the fact that each support post is made in the form of a telescopic connection of pipes of different diameters with the possibility of extending them from each other and is fixed with the help of an existing locking device. The hinge connection of horizontal crossbars with them, except the upper row of such bars that are railing, is made in random order, for example, by attaching a hinge to the upper end of the upper tube of the smallest diameter, and is carried out using additional ring elements mounted on the corresponding telescopic connecting tubes. The inner diameter of each of these annular elements, exceeding the outer diameter of the tube on which it is mounted, is less than the outer diameter of the next subordinate telescopic tube. Thus, it can move only vertically in a telescopic connection within this and above pipes. It makes it possible to support each of the ring elements with horizontal crossbars attached to them under their weight at a certain level of height of the vertical support post, determined by the height of the underlying tube of the telescopic connection. At the same time, the lower horizontal crossbar is hinged to the ring element of the largest diameter, put on the lower tube of the telescopic connection, and rested directly on the working flooring made in the form of a sideboard. The proposed device is not technically complex to implement. Its use increases the workers’ productivity, improves the working conditions, and ensures the safety of various construction works. Keywords: safety, construction, ease of use, prototype, fencing, scaffolding.

New Designs of Spectacle Lenses for the Control of Myopia Progression: A Scoping Review.

Myopia control with new designs of spectacle lenses is a flourishing area of research. The present work reviews the effectiveness of new designs (DIMSs, defocus-incorporated multiple segments; CARE, cylindrical annular refractive element; HALs/SALs, highly/slightly aspherical lenslets; DOT, diffusion optics technology) aiming at slowing myopia progression. A search through the PubMed database was conducted for articles published between 1 January 2003 and 28 February 2023. Publications were included if they documented baseline central refraction (SER) and/or axial length (AL) data, and the change in these parameters, in myopic children wearing new designs of spectacle lenses (treatment group) compared to myopic children using single-vision lenses, SVLs (control group). The selection process revealed nine suitable articles. Comparing the mean and standard error values of the treatment and control groups, the highest differences in the change in the SER and AL were -0.80 (1.23) D [95% CI: -1.053 to -0.547; p < 0.001] and 0.35 (0.05) mm [95% CI: 0.252 to 0.448; p < 0.001], respectively; the effect of treatment provided by a HAL design, compared to SVLs, led to a deceleration of 54.8% in the SER and 50.7% in the AL. However, the heterogeneity of the results prevents reaching strong conclusions about the effectiveness of these new designs.

Axial Ratio Improvement of Circularly Polarized Antenna Using Parasitic Elements for 5G Applications

A circular polarization (CP) antenna that can switch between right-handed circular polarization (RHCP) and left-handed circular polarization (LHCP) modes has been designed and introduced for 5G applications in the 3.5 GHz frequency band in this work. The proposed antenna comprises a crossed dipole fed by a 90° hybrid coupler. The axial ratio (AR) enhancement of 190 MHz is achieved by vertically stacking a substrate with a distance of λ / 4 from the ground plane, including an annular ring-shaped parasitic element above a circular-shaped disc. Consequently, by creating surface current rotation on the parasitic elements, the CP performance of the antenna is improved. According to the experiments, a wide impedance bandwidth of 930 MHz (3.19-4.12 GHz) and an overlapped AR bandwidth of 23.5% for both modes are achieved. The overall size of the antenna is 100 × 92.5 × 24 m m 3 , and the gain is stable across the operating frequency band with a peak value of 6.78 dBic.

Failure envelope considering the ultimate tensile capacity of suction caissons in sand

Little analytical work has been done to elucidate the ultimate capacity of suction caissons under vertical tensile (V), lateral (H), and moment (M) loads in soils. In this paper, in order to reveal the effect of vertical tensile, lateral, and moment loads on the ultimate capacity of suction caissons in sand, an analytical investigation was made using a traditional bearing capacity theory. Taking account of the vertical equilibrium of an annular element of a skirt, through the vertical tractions inside and outside the skirt of a suction caisson when a vertical tensile load is applied, the vertical displacement of the soils adjacent to the skirt of the suction caisson was presented. The most appropriate bearing capacity equation for predicting the experimental results was shown for suction caissons having an embedment larger than a diameter in sand. For the deformation-load responses of suction caissons with various embedment ratios in sand, subjected to inclined tensile loads, there was a good agreement between the results obtained from laboratory tests and those predicted by the present method. The failure surfaces, considering the ultimate tensile capacity in the H-M, H-V, and M−V planes, and in the H-M−V space, for suction caissons in sand, were presented.

Extended depth of focus for high-end machine vision lenses by annular achromatic add-on diffractive elements

In modern machine vision systems high-end lens objectives allow superior imaging on state-of-the-art sensor arrays due to highly corrected optical aberrations and large apertures. The resultant shallow depth of focus is a disadvantage, usually leading to programmatic attempts of extending it, with compromised image resolution. Here we present a simple optical system equipped with novel, annular peripheral add-on diffractive elements, allowing highly extended range of sharp imaging without any pre- or post-processing. The separation of main refractive focusing power from the proposed filters enables sparse kinoform zones leading to easy manufacturing and negligibly low chromaticity in polychromatic imaging. The undisturbed central region of the refractive objective sustains the full native imaging quality of the test Zeiss Otus lens. Convergent numerical and experimental results are presented, showing improved readability of alphanumerical symbols in a wide range of w20 defocus parameters up to 24 wavelengths. Robust neural network-based method of image quality assessment is also proposed based on statistical optical character recognition, allowing high dynamics and easy implementation in experimental use as compared to established methods.

Precise autofocus method based on an annular DOE and a cylindrical lens

With the wide application of lithography technology in the field of large-scale microstructure processing, it is necessary to achieve nano-scale autofocus in the range of hundreds of micrometers, which poses a new challenge to the autofocus method. Therefore, a precise autofocus method based on an annular optical diffractive element (DOE) and a cylindrical lens is proposed in this paper. Different from the traditional centroid method, this method uses an annular DOE and a cylindrical lens to modulate the beam section, so that the shape changes of the spot in the horizontal and vertical directions are inconsistent, that is, an elliptical annular spot is formed. Only one detector is used to detect the long axis and short axis of the spot respectively, and then the coarse focus position and the fine focus position can be calculated respectively. Combining these two results, we can perform autofocus with nanometer precision over a large range. In addition, our autofocus system is simple in structure. The feasibility and practicability of the method are verified by simulation and experiment.

Design and Development of Hub-less Wheel

Abstract: The present invention is related to a cycle or an engine-driven vehicle that moves on a bearing surface and more particularly on a road. In the case of a motorcycle, the front steering wheel is fitted with a first crown-shaped roller bearing being comprised of an outer annular element that supports the rim and an interior annular element that is connected to an arm. The carries at its front end a second crown-shaped roller bearing of which the interior elements are made integral by way of a lug of the interior annual element of the roller bearing and of which the interior annular elements of bearing is made integral with the arms device allow transmitting the steering force at a point located as close as possible to the contact area between the rim and the road. In addition to that, the vehicle device becomes more compact. due to hub mass, it is difficult in comparison to without hub, which can be easily steered in manual, The power is transmitted with the aid of gear Drive mechanism which is more efficient that the chain mechanism. Keywords: Hub-lees Wheel, Rim, Tire, Try Wheel, Roller

The stability of low-pitched von Mises trusses with horizontal elastic supports

Abstract. Purpose. The work’s aim is to study the horizontal supports stiffness impact, which simulate the conditions for supporting the domes upper tier on the von Mises trusses' stability. Methodology. A three-hinged truss' deformed scheme under applying a concentrated vertical load in the ridge joint was considered. An analytical method was used to obtain a generalized equation for the three-hinged trusses' stability criterion to determine the critical load depending on the design system's parameters such as the rods' inclination angle, the rods' stiffness, and the horizontal elastic supports stiffness. A two transcendental equations' system for the dependence of the load on vertical and horizontal displacements taking into account the rods' compression was obtained. Such equations' system's analytical solution through a generalized parameter - a variable rods' angle tangent, made it possible to obtain one equation for the dependence of the vertical load on the vertical and symmetric horizontal supports' displacement. The truss' stability numerical studies were carried out depending on the structure's design geometry. Findings. An analytical expression of the dependence for the load on the structure, which was reduced to the rod’s stiffness depending on the rods’ angle to the horizontal stiffness of the supports, was obtained. The low-pitched double-rod three-hinged trusses' nonlinear deformation nature depending on the elastic supports' stiffness and the rods' angle was confirmed. It was found that with the two-rod low-pitched three-hinged systems’ nonlinear deformation nature the ridge joint's snap-through effect takes place. It was found that the relative reduced critical load value decreases along with the rods' inclination angle decrease depending on the horizontal supports' stiffness. Scientific innovation. On the theoretical studies basis of the three-hinged two-rod low-pitched trusses with elastic horizontal supports deformed scheme a generalized analytical equation for the such systems' solution was obtained. The generalized analytical solution models the dome system annular elements stiffness through the horizontal supports' stiffness and determines the general lower tier elements stiffness effect on the dome uppermost tier structural system stability. Practical value. The obtained analytical equation makes it possible to determine the dome annular elements rational design parameters to ensure the upper tier stability.

A simple model to predict the energy loss due to leading edge roughness

In this paper a simple model to predict losses in annual energy production due to leading edge roughness or leading edge erosion from wind turbines is presented. Because detailed information about wind turbines not always are available, the input to this model requires only a few parameters: rated power, rotor radius, two Weibull parameters and categories of local damages. Therefore, some assumptions are made in the model. It was validated against a common implementation of a BEM code and showed good agreement in the loss of annual energy production.Also, a categorisation methods was proposed. The categories ranged between a and e corresponding to an undamaged blade and a severely damaged blade, respectively. This categorisation was made locally on the blade. The blade is divided into annular elements and each annular element is graded with a category. By summing up the annular elements on the blade, each with their categories, the total loss in energy production was predicted.

Large-range and high-precision autofocus method based on an annular DOE for a laser direct writing system.

We present a large-range and high-precision autofocus method based on an annular diffractive optical element (DOE) for a laser direct writing system. By analyzing the shape of the return spot, the defocus direction and the defocus amount can be obtained at the same time. The experimental results show that the linear detection range of the proposed method can reach at least 76 µm, the sensitivity can reach 100 nm, the detection accuracy can reach 100 nm, and the noise fluctuation does not exceed 50 nm. Apparently, with the advantages of a large detection range, high detection, and good stability, the automatic focus detection method proposed in this paper can be widely applied in various wafer-scale complex microstructure preparation systems.

Simulating Interaction of Liquid Steel with Gate Wall at Harmonic Motion

The problem of determining the forces of interaction of a viscous fluid with the cylindrical pipe wall is considered. It is assumed that near the pipe wall, the fluid motion is completely determined by viscous forces. The pipe moves along the streamline. The annular fluid element motion law is a special case of the Navier–Stokes equation in a cylindrical coordinate system. The equation is solved by the Fourier method in Bessel functions. Considering the orthogonality of the eigenfunctions, an equation for the squared norm is found. As an example, the case is considered when the pipe is subjected to vibration. Equations have been obtained for the velocities and viscous friction forces in the laminar sublayer. It has been found that when the pipe moves harmonically, the velocities and shear stresses at the pipe wall do not reach their maximum synchronously. The distribution of velocities and stresses in the section of the steel-pouring ladle gate channel has been considered for three vibration modes. The solution provided can be, in particular, used to determine the fluid–pipe wall interaction forces when the pipe is technologically affected by vibration, impulse, etc., as well as study moving joints such as piston, plunger, etc.

Pressure drop experiment with externally and internally cooled annular fuel bundles

Canadian Nuclear Laboratories (CNL) has developed an externally and internally-cooled annular fuel (ICAF) bundle that is considered to have improved thermalhydraulic characteristics as compared to the fuel bundles used in the conventional pressurized heavy-water-moderated-and-cooled reactors (PHWRs), such as the CANDU® reactors. The ICAF bundle consists of 24 annular fuel elements (or rods) and a solid central rod. The coolant flows through both the internal and external channels of each annular fuel element; the total flow in the flow tube is split into the flow inside the internal channels of the annular elements and that in the outside subchannels of the fuel bundle. The most compelling argument for this design, compared to the conventional solid-rod design, is the significant reduction in maximum fuel temperature for equivalent linear element ratings, due to significantly-enhanced heat transfer from fuel surfaces to coolant. The primary objective of the ICAF bundle development is to achieve higher burnups and higher power densities using advanced fuel cycles, with comparable or improved thermalhydraulic safety margins. This paper presents the results of a pressure drop experiment performed to investigate the hydraulic behavior of the ICAF bundle. Experimental data were obtained for the pressure distribution, the bundle misalignment junction signature and the flow split. The data can be used to develop predictive models to be implemented into the thermalhydraulics analysis toolset, and to validate the toolset for safety analyses in establishing reactor operating power and evaluating safety margin.

Enhanced antimicrobial activity of konjac glucomannan nanocomposite films for food packaging

This paper aims at providing a new strategy for developing konjac glucomannan-based antibacterial films with excellent performances. Here, novel nanocomposite films based on photodynamic and photothermal synergism strategy were developed by incorporating graphite carbon nitride nanosheets/MoS2 nanodots (CNMo) into konjac glucomannan (KGM) matrix. Scanning electron microscope, transmission electron microscope, high resolution transmission, high angle annular dark field and element mapping confirmed the successful fabrication of CNMo. The steady and dynamic rheological behavior as well as the good stability of film-forming solution showed that the intermolecular hydrogen bonding was formed. The influences of CNMo content on the structural, mechanical and thermal properties as well as hydrophobicity of KGM films were investigated. This film has a broad-spectrum antibacterial activity. It could prolong the shelf life of cherry tomatoes. Moreover, hemolysis and cells experiment confirm that this film is safe. This strategy is expected to broaden the application of antibacterial packaging.

Frequency and port reconfigurable MIMO antenna for UWB / 5G / WLAN band IoT applications

In this communication, a new compact multiple-input-multiple-output (MIMO) antenna design with frequency and port reconfigurable feature has been presented. The design consists of four orthogonally placed annular ring-shaped UWB monopole elements. Wideband to narrowband switching of each monopole element is done by PIN diodes placed between the fed line and stepped-impedance resonating stubs (SIRS). The reconfigurable frequency states are: UWB, mid-band 5G and WLAN. In narrowband, frequency spectrum is tunable using varactor diodes placed at middle of SIRS. The antenna ports can be tuned to operate as 4-port, or 2-port MIMO and it is also possible that all the ports operate at different frequency simultaneously. The concept is proved by simulation and measurement results which includes S-parameters, radiation patterns, gains, and envelop correlation coefficients.

Low-Profile Circularly Polarized Isoflux Beam Antenna Array Based on Annular Aperture Elements for CubeSat Earth Coverage Applications

This article presents an antenna array to produce a circularly polarized (CP) isoflux beam for CubeSat earth coverage applications. Distinguished from conventional arrays formed by identical elements, the proposed one is based on sequential rotation-fed concentric annular aperture elements. By adjusting the excitation phase, magnitude, and polarization of each annular aperture element, the radiation patterns of the array can be shaped to form isoflux beams. Radiation pattern modeling method is developed to obtain array radiation parameters. Besides, to effectively characterize the impedance matching of the radiators of the array with multiple excitations, an overall reflection coefficient is deduced from signal decomposition. A prototype operating at C-band (5 GHz) is designed, fabricated, and measured. It consists of a radiator and a feeding network. The radiator is formed by two annular aperture elements, of which the inner one is realized by a circular patch antenna while the outer one is formed by eight planar inverted-F antennas (PIFAs). The feeding network drives annular aperture elements in the manner of sequential rotation. In this way, a CP isoflux beam array with a low profile ( 0.078 λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> ), lightweight, and ease-of-integration for CubeSat is realized. The proposed array can also be extended to realize other shaped beams.

Generation of an Ultra-Long Optical Needle Induced by an Azimuthally Polarized Beam

In this manuscript, a method of generating an ultra-long optical needle (depth-to-width ratio 37.5:1) is proposed and demonstrated by focusing an azimuthally polarized beam. In theory, the action mechanism between the incident beam and the amplitude modulation element, the spiral phase modulation element, the focusing lens were studied based on the Richards and Wolf's theory. The relationship between the intensity distribution of the optical needle and the structure parameter of the element were obtained, thus leading to the complete design model and design standard. In experiment, the annular amplitude modulation element and spiral phase modulation element were fabricated by lithography. The optical needle was obtained based on a custom-designed optical setup in our laboratory. The optical system consists of an annular aperture (3.9-mm inner diameter, 80-μm annular width), a spiral phase plate (topological charge of 1), and an objective lens with numerical aperture of 0.95. Finally, an optical needle with a subwavelength size (0.416λ) and an ultra-long depth of focus (15.6λ) was obtained, showing an excellent agreement with our theoretical model.

Analysis of capability for improvement of basic mathematical model of electrode of ferro-alloy furnace

The article analyzes the Mathematical Model of The Self-Baking Electrode which is defined as basic. Its advantages and disadvantages are determined. Criterias for creating more advanced mathematical model for equalizing the thermal field of the Electrode are proposed.&#x0D; The problem of calculating the thermal field is solved by the the method of elementary heat balances of electrode. For this goal the simulated area is divided into annular (cylindrical) elements along the radius and height of the electrode.The calculation of the temperature field of the electrode is carried out in two stages: I – with boundary conditions and currents for the parts of the electrode facing to the center of the smelting furnace; II – with boundary conditions and currents for the parts of the electrode facing to the lining. &#x0D; The mathematical model takes into account an effect of the ribs and the hood on the distribution of electric current and Joule’s Heat over the cross section of the Electrode. In case heating ferromagnetic materials under impact of an electromagnetic field, the magnetic permeability at first decreases relatively slowly, and then droping down sharply as a certain temperature (Curie Point) is reached. The material loses its magnetic properties completely and goes into into a paramagnetic state.&#x0D; The value of the electrode current changes according to the graph from the starting value to the working value and then remains constant. The current density of the electrode along the radius is unequal due to the action of the surface effect, as well as due to existence of a metal hood and ribs, the electrical conductivity of which is higher than conductivity of special carbon paste.&#x0D; The goal of the work is to create modern mathematical model of the secondary current network of electric smelting furnace which could improve baking conditions of the Electrode and to reach the state of its temperature field to equable. This would create a stable mode of operation of the furnace.The paper analyzes the main features of the mathematical model of the secondary network of the smelting furnace, identifies the stages of development and formulates the main assumptionssimplifications that could be accepted wile creating this model.

Influence of frictional contact on indentation of elastic layer under surface energy effects

The paper examines the influence of frictional contact on an indentation problem of a finite-thickness elastic layer under a rigid flat-ended cylindrical indenter considering surface energy effects based on Coulomb friction model. The continuum-based approach corresponding to the complete version of Gurtin-Murdoch surface elasticity model is adopted to demonstrate the influence from surface energy. Normal and radial displacement boundary conditions in the contact region corresponding to the frictional indentation problem is formulated in the term of integral equations by employing the relevant displacement Green's function obtained by the use of Hankel integral transform. The contact tractions are solved by applying a collocation technique together with the assumption of a piecewise distribution for the tractions within each discretized annular ring element. The accuracy of proposed solution scheme is validated with existing solutions from classical continuum mechanics for frictional indentation problem of an elastic half-space. Selected numerical results are presented to demonstrate the influence of friction effects on the elastic fields of the layer under the influence of surface energy. It is found that the consideration of frictional contact makes the layer stiffer when compared to the frictionless indentation, and the influence of friction effect is smaller when the surface energy effects are accounted for. In addition, the elastic fields of the layer are clearly size-dependent and the elastic layer becomes stiffer with the presence of surface stresses.