Opposite Direction Of Rotation Research Articles

ОЦІНКА ЕФЕКТИВНОСТІ ПОЛЯРИЗАЦІЙНОЇ СЕЛЕКЦІЇ ЦІЛІ НА ФОНІ ПАСИВНОЇ ПЕРЕШКОДИ ЗА ДОПОМОГОЮ ПРИСТРОЮ, ЯКИЙ ВРАХОВУЄ ПРОСТОРОВІ ЗМІНИ КУТА ФАРАДЕЄВСЬКОГО ОБЕРТАННЯ В ІОНІЗОВАНОМУ СЕРЕДОВИЩІ В ПЛОЩИНІ ПОЛЯРИЗАЦІЇ СИГНАЛУ

The paper analyzes the studies of incoherently scattered ionospheric radio signals of long duration. The depolarization of the incoherently scattered signal was experimentally of incoherently scattered detected, which is due to the spatial variation of the Faraday rotation angle in the ionosphere of the signal polarization plane. It is proposed to use this effect for polarization selection of simple geometric shapes against the background of interference reflections from inhomogeneities in the electron concentration of the ionized medium. Also, a device was developed that implements the proposed method of polarization target selection. The scheme of the proposed polarization selection device contains two circular polarization antennas of the opposite direction of rotation, two optimal filters, two quadrature channels of synchronous detectors, four multipliers, two adders, two narrowband filters and a functional converter. It is assumed that the transmitting antenna is linearly polarized. In order to determine the operability of the device under various conditions and to evaluate its efficiency, the signal-to-noise ratio at the output of the device is calculated in the case where the backscattering matrix of the target and the matrix of the interference element (for example, dipole, angle reflector, etc.) are not diagonal, m .e. when a cross-polarization component appears when the signal from the target or from the interference element is reflected.

Wavy movements of epidermis monocilia drive the neurula rotation that determines left–right asymmetry in ascidian embryos

Tadpole larvae of the ascidian, Halocynthia roretzi, show morphological left–right asymmetry in the brain structures and the orientation of tail bending within the vitelline membrane. Neurula embryos rotate along the anterior–posterior axis in a counterclockwise direction, and then this rotation stops when the left side of the embryo is oriented downwards. Contact of the left-side epidermis with the vitelline membrane promotes nodal gene expression in the left-side epidermis. This is a novel mechanism in which rotation of whole embryos provides the initial cue for breaking left–right symmetry. Here we show that epidermal monocilia, which appear at the neurula rotation stage, generate the driving force for rotation. A ciliary protein, Arl13b, fused with Venus YFP was used for live imaging of ciliary movements. Although overexpression of wild-type Arl13b fusion protein resulted in aberrant movements of the cilia and abrogation of neurula rotation, mutant Arl13b fusion protein, in which the GTPase and coiled-coil domains were removed, did not affect the normal ciliary movements and neurula rotation. Epidermis cilia moved in a wavy and serpentine way like sperm flagella but not in a rotational way or beating way with effective stroke and recovery stroke. They moved very slowly, at 1/7 Hz, consistent with the low angular velocity of neurula rotation (ca. 43°/min). The tips of most cilia pointed in the opposite direction of embryonic rotation. Similar motility was also observed in Ciona robusta embryos. When embryos were treated with a dynein inhibitor, Ciliobrevin D, both ciliary movements and neurula rotation were abrogated, showing that ciliary movements drive neurula rotation in Halocynthia. The drug also inhibited Ciona neurula rotation. Our observations suggest that the driving force of rotation is generated using the vitelline membrane as a substrate but not by making a water current around the embryo. It is of evolutionary interest that ascidians use ciliary movements to break embryonic left–right symmetry, like in many vertebrates. Meanwhile, ascidian embryos rotate as a whole, similar to embryos of non-vertebrate deuterostomes, such as echinoderm, hemichordate, and amphioxus, while swimming.

SIMULASI NUMERIK PADA DIFFUSER AUGMENTED WIND TURBINES DENGAN ROTOR GANDA KONTRA ROTASI

Wind energy is one form of renewable energy in Indonesia and its potential is very large to be utilized. Wind energy can be converted into electrical energy using wind turbines. Horizontal axis wind turbine will be the subject of this study, where the wind turbine model will be given additional diffuser. In addition, this wind turbine model will also be developed from a single rotor wind turbine into a double rotor wind turbine with opposite rotation direction or counter rotation. This research uses numerical simulation method using ANSYS Fluent software to know wind turbine performance. Simulations were performed at wind speeds of 3 m/s, with the ratio of the length and diameter of the inlet diffuser 0.5; 1; 1.5; 2; and 2.5. Based on the simulation results, it can be seen that the greater the ratio of inlet length and diameter, the mechanical power generated by the wind turbine rotor is greater. Double rotor wind turbine with a length ratio and 2.5 inlet diameter produces the highest performance on the front rotor and rotor rear. The greater the ratio of the length and diameter of the inlet, the mechanical power generated by the front rotor and the rotor inside the diffuser also increases.

Modeling of fluid flow in a biological reactor of rotational type

The technology using for the replacement of damaged tissues the own cells of the patient, which are placed in a three-dimensional frame - scaffold, is promising for solving the problem of the bone tissue regeneration. A new biological reactor of the rotational type, in which the scaffold tissue rotates in a medium for cultivating the cells, was designed for the development of this technique. A numerical algorithm based on the ANSYS program was developed, which enables one to estimate in a new bioreactor the level of the mechanical load on the cells, which affects their pro-perties. The algorithm enables the computation of the values of the shear stress and static pressure acting on the scaf-fold surface. The computations have shown that the necessary shear stress is reached in the proposed rotational biore-actor on the outer side of the inner cylinder (0.002−0.1 Pa) in the range of rotation frequencies 0.083 < f < 0.233 Hz. At the same time, computational results have revealed the presence of an inhomogeneity in the mechanical action distribution along the scaffold tissue, which is due to the appearance of two Taylor vortices with opposite rotation directions in the gap between the cylinders. The experiments on the flow field visualization inside the rotational bio-logical reactor have shown a qualitative agreement of the flow character with computational results. The proposed numerical algorithm may simulate with sufficient accuracy the fluid flow in a real system. The obtained dependencies can be used in practice for creating an optimal microenvironment of the cells cultivated in the biological reactor.

Double-sided friction stir spot welding of steel and aluminum alloy sheets

Double-sided friction stir spot welding (FSSW) of dissimilar Al/steel alloy sheets was developed, and the effects of different tool rotational directions and plunge forces on the welding quality were investigated and compared with single-sided FSSW. Experimental results show that the fracture load increases with the increasing of plunge force, and double-sided FSSW can sustain higher fracture load than single-sided FSSW regardless of the plunge force. Two rotational directions result in similar fracture load of the welded part if the plunge force is less than 1.16 kN. If the plunge force is larger than 1.16 kN, opposite rotational direction achieves higher fracture load of the welding point. The formation of intermetallic compounds under different welding conditions at the welding joint was analyzed.

Magnetization Reversal Modes in Short Nanotubes with Chiral Vortex Domain Walls.

Micromagnetic simulations of magnetization reversal were performed for magnetic nanotubes of a finite length, L, equal to 1 and 2 μm, 50 and 100 nm radii, R, and uniaxial anisotropy with “easy axis” parallel to the tube length. I.e., we considered relatively short nanotubes with the aspect ratio L/R in the range 10–40. The non-uniform curling magnetization states on both ends of the nanotubes can be treated as vortex domain walls (DW). The domain wall length, Lc, depends on the tube geometric parameters and the anisotropy constant Ku, and determines the magnetization reversal mode, as well as the switching field value. For nanotubes with relative small values of Lc (Lc/L < 0.2) the magnetization reversal process is characterized by flipping of the magnetization in the middle uniform state. Whereas, for relative large values of Lc, in the reverse magnetic field, coupling of two vortex domain walls with opposite magnetization rotation directions results in the formation of a specific narrow Néel type DW in the middle of the nanotube. The nanotube magnetization suddenly aligns to the applied field at the switching field, collapsing the central DW.

Numerical investigation and experimental test on aerodynamic noises of the bionic rear view mirror in vehicles

At present, there are some researches focusing on optimization of aerodynamic noises on rear view mirrors, but researches on bionic noise reduction of rear view mirrors are rarely reported. Therefore, with an original rear view mirror as the basic model, the paper applied a head convex hull of a dung beetle to the original rear view mirror cover to obtain a bionic rear view mirror, then conducted numerical computation for aerodynamic noises of the bionic rear view mirror and compared the computational results with the original model. Finally, in order to verify correctness of computational results of aerodynamic noises of the rear view mirror, wind tunnel test was conducted on the rear view mirror. Experimental and numerical simulation results were highly consistent in the whole frequency band, so the wind tunnel test could be replaced by numerical simulation. Only one obvious vortex was behind the bionic rear view mirror, but two obvious vortexes with the opposite rotation directions were behind the original rear view mirror. The bionic rear view mirror did not present vortexes near the lateral window, so impacts of vortexes on noises in the vehicle could be eliminated effectively. Pressure difference in front of and behind the bionic view mirror was smaller than the pressure difference in front of and behind the original rear view mirror. Pressure resistance caused by the convex structure outside the rear view mirror was reduced, so noise reduction could be promoted. The convex structure mainly affected the aerodynamic noise in mid-high frequency regions. Compared with the original rear view mirror, noise reduction effects of the bionic rear view mirror were obvious, where the noise reduction amplitude reached 10dB. Noise source size and intensity of the bionic rear view mirror were reduced obviously.

Double synchronization states of two exciters with horizontal asymmetric structure in a vibrating system

Synchronization of two exciters with asymmetric structure is more widely used in engineering, such as vibrating conveyer, dewatering screen, vibrating screen, however, the synchronization state of two exciters with asymmetric structure in the sub-resonant and super-resonant states is less considered, and it is a valuable research topic. Firstly, we establish a kind of weakly nonlinear vibrating system driven by two exciters with opposite rotation directions and asymmetrical structure. Using Lagrange equations, the differential equations of the vibrating system are obtained. Secondly, we apply Fourier series expansion to obtain the nonlinear elastic force of the nonlinear stiffness. Thirdly, we introduce the modified averaging method of small parameters and Hamilton’s principle to get the criterions of synchronization synchronization stability of two exciters. The theoretical analysis shows that the phase differences are stabilized in the vicinity of Pi phase difference in a super-resonant state when l0 approaches to le, otherwise, in the neighborhood of zero phase difference in a sub-resonant state. Then, the above theory is verified by experiments. The stable phase difference, amplitudes responses and energy consumption are also discussed. This research provides the foundation and guidance for the synchronization of two exciters with horizontal asymmetrical structure and engineering design.

К вопросу шелушения зерна в пневмомеханическом шелушителе

The article shows the theoretical study of percussive interaction of a grain, which is accelerated by the rotor peelers, with a deck. Theoretically, we defined fracture strength of grain structural elements in case of possible directions of grain and grain impact conditions on deck – under the condition of fixed deck, provided its rotation in the direction of rotor rotation, provided its rotation in the direction opposite the rotor rotation. The work and expended kinetic energy, required for such a failure, was found; the concept of grain recovery rate as the ratio of the kinetic energy before it hit the deck and after was given. Efficiency coefficient of the entire system was defined for different embodiments of grain pin on deck. It is proved that the most effective grain peeling will occur when the deck rotate in the opposite direction of the rotor rotation. In this case, the grain is moved, firstly, in air stream, generated by the rotor, as moving closer to the deck surface it moves in the air flow, generated by it, and changes its direction to reverse movement. That flow is easily controlled by changing the speed of the deck, which makes it possible to obtain a straight line (perpendicular to) hit the grain of it. The carried studies reveal more fully the grain interaction with the deck in the work area of rotor peelers.

Entropy Generation and Natural Convection of Air under a Magnetic Quadrupole Field in a Square Enclosure

The natural convection and entropy generation of air are numerically investigated in a two-dimensional square enclosure under a magnetic quadrupole field. In this study. The finite-volume method is applied to solve the coupled equation for flow, energy and entropy generation. Simulations are conducted to obtain solutions in terms of streamlines, isotherms, local entropy generation contours, total entropy generation, Bejan number for various ranges of the magnetic force parameter and Rayleigh number in a nongravitational field. Two symmetric cells with the same strength but opposite rotation directions are observed with the flow filed. Total entropy generation increases with increasing the magnetic force number. However, the average Bejan number holds the reverse trend. The magnetic field has a broad spectrum of applications in engineering areas to control natural convection. The local and total entropy generation presented in this study can be useful addition where one wants to minimize the irreversibility of the system.

Passive control of a single flexible flag using two side-by-side flags

Numerical simulations using an improved version of the immersed boundary method are performed to explore a passive control concept for a single flexible flag in a viscous uniform flow. In order to control a single flag passively, we utilize the distinct dynamics of two side-by-side flags, characterized by in-phase and out-of-phase flapping modes depending on their spanwise gap distance. When the two side-by-side flags are in an in-phase flapping mode with a small spanwise gap distance, the flapping amplitude of a single downstream flag is highly enhanced due to synchronization between the vortices shed from the upstream and downstream flags. However, when the two upstream flags flap in an out-of-phase flapping mode with a large spanwise gap distance, the flapping of the single flag is significantly weakened with a reduction of the dominant flapping frequency. Because the upstream flags induce consecutive counter-rotating vortex pairs with a high frequency due to their flapping mode (out-of-phase state), relatively strong interaction with an upcoming vortex of the opposite rotational direction leads to flapping inhibition of the single flag. For an intermediate spanwise gap distance, the vortex-to-vortex interaction between the flags becomes more complicated, and a change of the flapping phases of the two side-by-side flags depending on streamwise gap distance between the upstream and downstream flags occurs. The interactions between coupled flags are documented through the root-mean-square cross-stream tail positions, frequency, drag coefficient, vorticity and pressure contours of the flags with varying non-dimensional parameters relevant to the problem. The proposed passive control concept of a single flag using two side-by-side flags is applicable to the development of energy harvesting systems to extract more energy and flapping control systems to suppress vibration.

Vertical dense jet in flowing current

The discharge of brackish water, as a dense jet in a natural water body, by the osmotic power plants, undergoes complex mixing processes and has significant environmental impacts. This paper focuses on the mixing processes that develop when a dense round jet outfall perpendicularly enters a shallow flowing current. Extensive experimental measurements of both the salinity and the velocity flow fields were conducted to investigate the hydrodynamic jet behavior within the ambient current. Experiments were carried out in a closed circuit flume at the Coastal Engineering Laboratory (LIC) of the Technical University of Bari (Italy). The salinity concentration and velocity fields were analyzed, providing a more thorough knowledge about the main features of the jet behavior within the ambient flow, such as the jet penetration, spreading, dilution, terminal rise height and its impact point with the flume lower boundary. In this study, special attention is given to understand and confirm the conjecture, not yet experimentally demonstrated, of the development and orientation of the jet vortex structures. Results show that the dense jet is almost characterized by two distinct phases: a rapid ascent phase and a gradually descent phase. The measured flow velocity fields definitely confirm the formation of the counter-rotating vortices pair, within the jet cross-section, during both the ascent and descent phases. Nevertheless, the experimental results show that the counter-rotating vortices pair of both phases (ascent and descent) are of opposite rotational direction.

Rotating Snakes Illusion-Quantitative Analysis Reveals a Region in Luminance Space With Opposite Illusory Rotation.

The Rotating Snakes Illusion employs patterns with repetitive asymmetric luminance steps forming a “snake wheel.” In the underlying luminance sequence {black, dark grey, white, light grey}, coded as {0, g1, 100, g2}, we varied g1 and g2 and measured illusion strength via nulling: Saccades were performed next to a “snake wheel” that rotated physically; observers adjusted rotation until a stationary percept obtained. Observers performed the perceptual nulling of the seeming rotation reliably. Typical settings for (g1, g2), measured from images by Kitaoka, are around (20%, 60%). Indeed, we found a marked illusion in the region (g1≈{0%–25%}, g2≈{20%–75%}) with a rotation speed of ≈1°/s. Surprisingly, we detected a second “island” around (70%, 95%) with opposite direction of the illusory rotation and weaker illusion. Our quantitative measurements of illusion strength confirmed the optimal luminance choices of the standard snake wheel and, unexpectedly, revealed an opposite rotation illusion.

プレスワールフィンによる旋回流中のプロペラ翼形状最適化に関する研究

Various energy-saving technologies have been developed because improved fuel consumption contributes. Pre-swirl fins, which consist of multiple fins installed in front of a propeller, swirl inflow to the propeller in the opposite direction of the propeller rotation to recover the waste energy of a propelled ship. The propeller mast be designed in consideration of pre-swirl inflow, because velocity distributions flowing into the propeller are changed by pre-swirl fin. This paper describes a propeller optimization method in consideration of pre-swirl inflow using real-coded genetic algorithm. A propeller was designed by utilizing the present method. Propeller tests in which influence of pre-swirl inflow of the original and improved propellers were carried out.

Effects of Orbital Motion on the Velocity Field of Boundary Layer Flow over a Rotating Disk

The purpose of this study is to investigate experimentally the effects of orbital motion on the velocity field of boundary layer flow over a rotating disk. The characteristics of velocity field at a fixed orbital angular section measured by a hot-wire anemometer show that the structure of the 3-dimensional boundary layer flow is deformed elliptically and displaced in a certain direction that is not in the orbital radial direction, but the direction of deformation depends on the combination of orbital and rotational directions. For coincide orbital and rotational directions, there are regions where the intensity of low-frequency disturbances increases rapidly in a certain central region (laminar region under pure rotation). The transient vortices, which form streaks on the coating film, are considered to be destroyed by low-frequency disturbances. However, for opposite orbital and rotational directions, the low-frequency disturbances are not observed in any section. As the adding orbital speed increases, the intensity of velocity fluctuations in the turbulence region becomes larger in the expected except in a certain region. This location of the region also depends on the direction of deformation or the combination of orbital and rotational directions.

Microstructure, crystallographic texture and mechanical behaviour of friction stir processed Mg-Zn-Ca-Zr alloy ZKX50

The feasibility of applying friction stir processing (FSP) to locally homogenise and to refine the microstructure of a recently developed Mg-Zn-Ca(-Zr) alloy, ZKX50, has been examined. The application of a single pass of FSP resulted in dissolution of coarse intermetallic particles at dendrite boundaries and grain refinement, from an average grain size of ~60µm in the as-cast state to ~1.2µm. The microstructure in the processed zone exhibited banding as well as a variation in grain size across the stir zone (SZ). A second, fully overlapping FSP pass at a lower rotational speed, with the same or the opposite rotational direction, caused further microstructural refinement down to submicron levels and a more homogeneous grain size distribution. A strong basal fiber texture developed as a result of the first FSP pass; application of a second pass enhanced the crystallographic texture induced by the first one. Single-pass FSP resulted in doubling the microhardness within the SZ relative to that of the as-cast material, however, the hardness distribution within the SZ was non-uniform, in agreement with the banded microstructure observed. The application of a second pass brought about a further increase in microhardness, reflecting the more pronounced grain refinement observed. Tensile tests with loading along the processing direction did not result in an enhancement of the tensile strength over that of the base material, whilst the ductility as measured by the tensile elongation was doubled. Tensile tests on notched specimens with load applied in the transverse direction returned higher strength values. This anisotropy in tensile properties was explained in terms of the evolution of micro-texture.

Computational simulations of hydrogen circular migration in protonated acetylene induced by circularly polarized light.

The hydrogens in protonated acetylene are very mobile and can easily migrate around the C2 core by moving between classical and non-classical structures of the cation. The lowest energy structure is the T-shaped, non-classical cation with a hydrogen bridging the two carbons. Conversion to the classical H2CCH(+) ion requires only 4 kcal/mol. The effect of circularly polarized light on the migration of hydrogens in oriented C2H3 (+) has been simulated by Born-Oppenheimer molecular dynamics. Classical trajectory calculations were carried out with the M062X/6-311+G(3df,2pd) level of theory using linearly and circularly polarized 32 cycle 7 μm cosine squared pulses with peak intensity of 5.6 × 10(13) W/cm(2) and 3.15 × 10(13) W/cm(2), respectively. These linearly and circularly polarized pulses transfer similar amounts of energy and total angular momentum to C2H3 (+). The average angular momentum vectors of the three hydrogens show opposite directions of rotation for right and left circularly polarized light, but no directional preference for linearly polarized light. This difference results in an appreciable amount of angular displacement of the three hydrogens relative to the C2 core for circularly polarized light, but only an insignificant amount for linearly polarized light. Over the course of the simulation with circularly polarized light, this corresponds to a propeller-like motion of the three hydrogens around the C2 core of protonated acetylene.

ON THE ROTATION OF SUNSPOTS AND THEIR MAGNETIC POLARITY

ABSTRACT The rotation of sunspots of 2 yr in two different solar cycles is studied with the data from the Helioseismic and Magnetic Imager on board the Solar Dynamics Observatory and the Michelson Doppler Imager instrument on board the Solar and Heliospheric Observataory. We choose the α sunspot groups and the relatively large and stable sunspots of complex active regions in our sample. In the year of 2003, the α sunspot groups and the preceding sunspots tend to rotate counterclockwise and have positive magnetic polarity in the northern hemisphere. In the southern hemisphere, the magnetic polarity and rotational tendency of the α sunspot groups and the preceding sunspots are opposite to the northern hemisphere. The average rotational speed of these sunspots in 2003 is about 0.°65 hr−1. From 2014 January to 2015 February, the α sunspot groups and the preceding sunspots tend to rotate clockwise and have negative magnetic polarity in the northern hemisphere. The patterns of rotation and magnetic polarity of the southern hemisphere are also opposite to those of the northern hemisphere. The average rotational speed of these sunspots in 2014/2015 is about 1.°49 hr−1. The rotation of the relatively large and stable preceding sunspots and that of the α sunspot groups located in the same hemisphere have opposite rotational direction in 2003 and 2014/2015.

Friction and 2D position measurements in small journal bearings

Shaft position and friction torque as a function of radial loading and rotational speed are important parameters in the theory of lubrication. However, to date values for small bearings taking into account manufacturing tolerances are not available. The method described in this work allows precise friction torque and 2D position measurements on small journal bearings under variation of the important parameters: speed, radial loading, lubricant and gap width. The system developed is able to capture simultaneously the friction torque as well as the 2D relative displacement between shaft and bearing using laser-triangulation which reveals the displacement trajectory under variation of speed and the dynamic behavior (half-frequency whirling and critical speeds). If displacement is considered for the friction torque measurement, an improvement in measurement accuracy is achieved when compared to previously reported techniques. Geometrical tolerances, which are of high importance in miniature bearings, are identified by two measurements in opposite direction of rotation and corrected.

Effect of the shaft eccentricity and rotational direction on the mixing characteristics in cylindrical tank reactors

Strategy of the shaft eccentricity is introduced to enhance the mixing characteristics in a flat bottomed cylindrical vessel without baffles. The mixing is ensured by a six-curved blade impeller. Three solutions which are models of food emulsions are used as working fluids. These solutions have a shear thinning behavior modeled by the power-law. The effects of fluid properties, stirring rates, impeller rotational direction and impeller eccentricity on the 3D flow fields and power consumption are investigated. Three values of impeller eccentricity are considered, namely 0%, 24% and 48% of the vessel diameter. It is found that the opposite clockwise rotational direction reduces the power consumption, compared with the clockwise rotational direction. Also, the obtained results show that an impeller placed at an eccentric position between 24% and 48% of the vessel diameter and at the third of the vessel height may ensure the best mixing characteristics.