Rectangular Rods Research Articles

DETERMINATION OF YOUNG’S DYNAMIC MODULUS OF POLYMER MATERIALS BY RESONANCE VIBRATING-REED METHOD

The paper deals with its own oscillations of a rectangular rod with a cross section of a rectangular shape. The method of determining real part of Young's dynamic modulus and tangent of mechanical loss of samples in the form of rods of a number of polymer materials by means of resonant vibrating-reed method are proposed. Experimental setup, algorithm and software for determining the amplitude of the sample oscillations are developed. The accuracy of measurements was determined and a comparative analysis of results was performed with data obtained by other methods.

Rectangular Dielectric Rod Antenna Fed by Air-Substrate Parallel Strip Line

In this paper, a rectangular dielectric rod antenna fed by an air-substrate parallel strip line is proposed. The dielectric rod has a compact and regular structure, which is easy to fabricate. The matching of the antenna is mainly determined by the parallel strip line, which simplifies the design process. Fed by an air-substrate parallel strip line, the antenna obtains a relatively uniform magnitude distribution on the surface and a moderate phase constant. With the length of 6 wavelengths at the center frequency of 6 GHz, the antenna generates a high measured gain of 16.7 dBi. The measured 1 dB gain bandwidth is about 18.3%. Over the entire operating band from 5.4 to 6.6 GHz, a stable endfire radiation pattern and a good matching are achieved by the antenna.

Numerical Study of Flow Past Three Rectangular Rods at Unequal Gap Spacing

Objectives: To examine the effect of unequal gap spacing for flow past over three rectangular rods a fixed Re (Reynolds number) and Aspect Ratio (AR). Methodology: A two dimensional (2-D) numerical study of flow over three rectangular rods is conducted by using Single Relaxation Time Lattice Boltzmann Method (SRT-LBM). The gap spacing (g) between the rods is varied from 0.5 to 7 with fixed Reynolds number i.e., Re = 150 (Re = .U∞d/ υ., where U∞ is uniform velocity, d is size of an object and υ is the kinematic viscosity) and aspect ratio AR = 0.25 (where, AR = l/w, l is the length and w is the width of the rods). Different flow structures, power spectra analysis of lift coefficients and force statistics are studied for this analysis at small, moderate and large gap spacing. Findings: The present study revealed that the gap spacing between the rods has a great impact on the flow behaviour. Therefore, different flow patterns are observed and some of them are outlined as, i). Shear layer reattachment (SLR), ii). Semi developed single bluff body (SDSBB), iii). Fully developed vortex shedding (FDVS), iv). Semi developed irregular vortex shedding, v) Fully generated two row single bluff body, vi). Semi developed irregular single bluff body (SDISBB) and vii). Critical flow (CF) patterns. The critical flow behaviour is observed at the gap spacing (g1 , g2 ) = (5, 2.5), (here, g1 is the gap between upstream rods to middle one and g2 is the gap between middle rods to downstream rectangular rod). In force statistics analysis, the values of Cdmean and Strouhal number are computed at different spacing ratios. The value of mean drags coefficients for all three rodsat g1 = 3 is approximately same, but at g1 = 1 and 5, the maximum value of Cdmean is observed for C2 as compared to C1 and C3, that is 6.91. Furthermore, Strouhal number values are much less than the single rod (SR) value for all three chosen small, moderate and large gap spacing values. The maximum value of St is examined at (g1, g2) = (1, 1) i.e 0.19. Keywords: Drag Coefficient; Rectangular Rods, Single Relaxation Time Lattice Boltzmann Method, Vortex Shedding Suppression

Increase in terahertz radiation power of plasmonic photoconductive antennas by embedding buried three-stepped rods in electrodes.

In this work, a periodic structure with three-stepped metallic rods is designed for increasing terahertz (THz) radiation power of plasmonic photoconductive antennas (PCAs). Embedding this structure in electrodes of PCAs increases power of incident laser beam at 0.8 µm wavelength transmitted into the LT-GaAs substrate from 35% in a plasmonic PCA with rectangular rods to approximately 100%. Obtained analytical results in this study along with measurement results, reported in the literature, confirm that generated THz current of plasmonic PCA is increased up to 82% by using the buried three-stepped rods instead of rectangular rods. Consequently, THz radiation power is enhanced by 226%. Therefore THz radiation power of conventional plasmonic PCAs can be effectively enhanced by the designed buried three-stepped metallic rods.

Unsteady Combustion Modes in Rectangular Rods

Unsteady modes of gasless combustion in rectangular rods prepared from a mixture of two powdered reagents with an admixture of low-melting inert metal powder were explored by numerical modeling. Rods with square cross section were found to burn in a mode of spinning combustion. The number of spinning hot spots is defined by sample dimensions. On going to the configuration of long plates with the same cross area, a mode of spinning combustion gradually transformed to that of frontal one.

One-dimensional porous Co3O4 rectangular rods for enhanced acetone gas sensing properties

One dimensional porous Co3O4 rectangular microrods (MR) are designed and successfully prepared by a distinctive electrospun precursor-hydrothermal regulation-annealing treatment strategy while Co3O4 nanofibers (NF) are also synthesized for comparison by directly calcining precursors without hydrothermal treatment. The hydrothermal treatment before annealing process results in morphology and structure transition of Co3O4 products from compact solid nanofibers to porous rods. When applied as a gas sensing material, Co3O4 porous rods based sensors exhibit enhanced gas sensing properties in terms of rapid response time (3 s), recovery time (5 s), good selectivity and stability towards 100 ppm acetone gas at a relatively low working temperature of 200 °C. Meanwhile, the response of Co3O4 porous rods toward 100 ppm acetone reaches approximately 5 times higher than that of solid Co3O4 nanofibers. The enhanced acetone gas sensing properties of Co3O4 rectangular porous rods are believed to originate from its porous structure and large surface area, facilitating gas adsorption and surface reaction and causing significant change in the thickness of holes accumulation layer (HAL). Feasible morphology-adjusting strategy and enhanced acetone gas sensing performances further highlight the advantage of as-prepared Co3O4 porous rods in future acetone real-time monitoring.

Influence of non-linearity of hardening curve on elasticoplastic bend of rectangular rod

Influence of non-linearity of hardening curve on elasticoplastic bend of rectangular rod

The Natural Waves of a 1D Lattice of Rectangular Dielectric Rods

The problem about the eigen waves of the infinite periodic lattice of rectangular dielectric rods located in a plane waveguide is considered. The boundary value problem is solved with the partial domain method, and the dispersion equation for the propagation constant of an eigen wave is obtained. The fields of eigen waves are found. The expression for the characteristic impedance of the fundamental wave is obtained. Results of the numerical investigation of the behavior of the moderating ratio and the characteristic impedance of the fundamental wave of the lattice are presented.

Comparison of three-phase transformers with rectangular and circular rod contour of planar laminated magnetic cores (mass and cost indicators)

Purpose. In transformers of mass productions low power planar magnetic cores with a rectangular cross section of rods are used. With a capacity of more than 16 kV∙A and high power, transformers with circular forming loops of rods and winding coils are produced. In recent decades, in order to reduce the complexity of manufacturing, the transformers power with rectangular sections of magnetic circuits cores has increased. However, there is no analytical study of the effect of replacing circular core loops and winding coils on rectangular ones. Methodology. The influence analysis of the change in the rods configuration on the mass and cost is performed by the method of invariant and structural-parametric synthesis of electrical machines with optimized dimensionless indicators. Results. Indicators values comparison gives an objective assessment of the advantages or disadvantages of the considered variant with respect to base analog. Originality. It has been established that use of rectangular sections of rods and copper or aluminum windings forming loops in an electromagnetic system leads to an improvement in three-phase transformer mass performance of a relative to the analogue with circular generating loops. The change in mass-value indicators depends on the rods filling factor of the circular contour with rectangular packages of electrical steel. Practical value. Three-phase planar electromagnetic systems of 1–110 kV voltage class with rod cores and circular and rectangular generating circuits are distinguished by minimal mass and cost indicators by 5,76–5 % and 7,8–6,6 % and 2,5–2,3 % and 2,93–2,7 % with the rods filling factor 0,786 and 0,925 in variants with copper windings. These indicators, when used in aluminum windings, differ by 4–3,54 % and 6,3–4,9 % and by 1,8–1,75 % and 2,67–2,07 %.

To the approximation of rectangular and complex cross-sections of reinforced concrete structures under the action torsion with bending

Special analytical method for determining tangential tension stresses in reinforced concrete structures operating in conditions of complex resistance –torsion with bending is proposed in this paper. Its peculiarity consists in the approximation of rectangular and any complicated cross-sections of reinforced concrete structures with the help of their division into squares with the circles inscribed there in, connected together into a single monolithic figure. The dependence of tangential torsion stresses becomes valid on the distance to the centre of the circle under consideration within each j-th circle. The further the circle from the centre of the rectangle is located, the greater its moment of inertia becomes and the maximum stresses are reached in the middle of the rectangle the long sides. Such model makes it possible to remove the question of the necessity using of special tables also for their calculation in the elastic stage. Also it makes possible to separate the stress-strain state in a whole set of circular sections from the additional field associated with the deformation of the rectangular section. The authors corrected and significantly supplemented the dependencies for taking into account the deplanation of a rectangular cross-section rod. Attention is focused on the physical essence of longitudinal displacements caused by deplanation, an analogy with elementary movements caused by shearing forces is carried out. In the study, the classification of spatial cracks for reinforced concrete rod structures under the action torsion with bending was generalized; while the process of spatial cracks formation of the first, second, and third types is tied to the proposed method for determining tangential stresses (angular deformations) for complex cross-sections. The proposed dependencies allow us to search for the values of the model design parameters at of the stress-strain state stages of the reinforced concrete rod structure, including in the plastic and in the limiting stages. The components of the torsion stress (angular deformations) are again synthesized and separated by the proposed method for the convenience of analysis in principal stresses tensors (main strains). Transformational transitions from a cylindrical to a Cartesian coordinate system and the attraction of local coordinate systems made it possible to simplify the equations as much as possible. Moreover, the equations are constructed in such a way that the resolving system does not turn into a decaying system. The physical interpretation of the solution obtained, with respect to the problem of crack resistance, is that it allows us to search for the minimum generalized load that corresponds to the formation of the first, second or third spatial crack types and the coordinates of their formation point. As a result, the effectiveness of the proposed method is shown with approximating rectangular and complex cross sections of reinforced concrete structures under the action torsion with bending and taking into account physical nonlinearity, deplanation of cross-sections, pre stressing in longitudinal and transverse reinforcement and the influence of local stress fields.

Novel Single-Crystal Hollandite K1.46Fe0.8Ti7.2O16 Microrods: Synthesis, Double Absorption, and Magnetism.

Novel multifeatured hollandite K1.46Fe0.8Ti7.2O16 (KFTO) was synthesized by a simple hydrothermal method. Magnetic KFTO microrods were well controlled to long rectangular rods with pyramid-shaped tops. A KFTO growth mechanism was proposed on the basis of examining phase and morphology of the samples acquired at different reaction times. The KFTO morphology was confirmed by the calculated surface energies. The UV-vis diffuse reflectance spectra of KFTO microrods showed double absorption with band gaps of 2.01 and 2.16 eV, which was further confirmed by photoluminescence. First-principles studies revealed that the double absorption and magnetic properties originate from the d-d transitions of Fe3+ under the crystal field. The magnetic property could be applied in ferromagnetic semiconductor devices and the double absorption could be applied in visible-light harvesting. This work highlights the multifunctional KFTO microrods with low cost and environmental friendliness.

Numerical analysis of surface and edge states in slabs, stripes, rods and surface steps of topological insulators

By numerically solving the effective continuous model of a topological insulator with parameters corresponding to the band structure of the topological insulator Bi2Se3, we analyze possible appearance of one-dimensional states in various geometries. Massless Dirac fermions are found at the edges of thin ribbons with surface oriented not only along the van der Waals gap but also in the perpendicular direction. Thick rods and slabs with surface steps host massive modes localized on surface faces. We argue that the the origin of the massive modes is due to the difference in the Dirac point energy of adjacent faces. The absence of one-dimensional states near edges of a large rectangular rod and surface steps is demonstrated.

Biaxial layering transition of hard rodlike particles in narrow slitlike pores

The phase behavior of hard rectangular rods with length L and diameter D is studied in a narrow slit-like pore using the Parsons-Lee density functional theory. Using the restricted orientation approximation, we find strong adsorption at the walls with planar ordering, second order uniaxial-biaxial ordering transitions and first order layering transitions. The layering transition takes place between two fluids having n and n+1 layers, where the layer spacing is in the order of D. In the case of weak shape anisotropy (L/D=3), the coexisting fluids can be either uniaxial or biaxial, while both phases are found to be biaxial for L/D=6 and L/D=9. Interestingly, even two or more layering transitions can be observed with increasing density at a given shape anisotropy and pore width.

High-Performance Finned Tubes for Production Facility Heating Systems

The values of the optimal height of the ribs and their optimal placement step on the surface of the heating device are determined. It was possible to determine that the installation of rectangular rods with a step of 8.2 mm on the surface at an angle of 90 degrees to the horizon, leads to an increase in the local coefficient of convective heat transfer to 200% compared to the surface on which there are no rods. It was found that the simplex acts as a separate parameter that affects the local coefficient of convective heat transfer on a surface with rectangular bars.

Tratamento de fraturas e luxações toracolombares com uso de hastes retangulares e losangulares

O tratamento de fraturas e luxações da coluna toracolombar requer descompressão do saco dural e raízes, alinhamento do canal vertebral com estabilização e artrodese da coluna. Existem alguns procedimentos para esse propósito e, nos últimos anos, surgiram modificações e simplificações. Dentro desse aspacto, 15 pacientes foram tratados com fenestração, facetectomia e redução, utilizando-se hastes retangular ou losangular com fios sublaminares. Obtivemos correção ideal da deformidade com excelente estabilidade. Não utilizamos coletes e os pacientes foram mobilizados precocemente do leito para deambulação ou fisioterapia.

UTILIZATION OF FREE CONVECTION IN COOLING SYSTEMS FOR ELECTRONIC EQUIPMENT

The values of the optimal height of the ribs and the optimum pitch arrangement of ribs on the surface of the radiator were detected. Criterial dependences for calculation of heat transfer at the surface that is at an angle of 90 degrees to the horizon in the presence of rectangular bars with free air convection were obtained. In my research, an attempt is made to determine the values of the optimal height of the ribs and the optimal spacing of the ribs on the surface of the radiator, as well as to obtain empirical relations in a dimensionless form to calculate the local coefficient of convective heat transfer on the surface at an angle of 90 degrees to the horizon, under free air convection. It was possible to determine that the installation of rectangular rods with a step of 8.2 mm on the surface at an angle of 90 degrees to the horizon, leads to an increase in the local coefficient of convective heat transfer to 200% compared to the surface on which there are no rods. experimental work area , free- convection flow, heat transfer coefficient, radiator, heat carrier

Tunable beam propagating characteristics of two-dimensional rectangular-rod photonic crystals based on self-collimation effect

The light beam transmission characteristics of the two-dimensional photonic crystal structures consisting of a square lattice of rectangular dielectric rods are studied. Through optimizing the parameters of the structure, the self-collimated light propagation within a large frequency region is achieved, and the corresponding light propagation direction can be altered through rotating the rectangular rods in the square lattice, which is explained by the analysis of the equi-frequency surface contours. A compound structure composed of rectangular rods with different rotating angles is proposed in this paper, which has different kind of functions depending on the incident light beam’s spatial width and incident location. The single-channel collimating propagation with different forward directions, two-branch-channel splitting with adjustable energy ratio, three-branch-channel splitting with different output beams’ propagation directions can all be achieved. These kinds of devices can help expand the application of energy beam splitters in the optical circuits system and realize miniaturization integration.

Thin Films with Perpendicular Tetragonally Packed Rectangular Rods Obtained from Blends of Linear ABC Block Terpolymers.

A binary blend of poly(isoprene-block-styrene-block-(2-vinylpyridine)) (ISP) triblock terpolymers, having the same chain length but different compositions, was used to achieve an ordered lattice with 4-fold symmetry of rectangular-shaped rods of poly(isoprene) (I) and poly(2-vinylpyridine) (P). In given conditions, the I and P domains were oriented perpendicularly to the substrate, providing an appealing type of templates for nanopatterning. Thin films were prepared by spin coating, exposed to solvent vapor (providing morphological reorganization), and then characterized by atomic force microscopy, transmission electron microscopy, and grazing-incidence small-angle X-ray scattering. Selective I and P identifications were carried out by AFM and TEM on a model ISP, as well as development of a technique of electronic contrast enhancement to better assign the self-assembly structure in GISAXS.

Mathematical Modeling of a Linear-Induction Motor Based on Detailed Equivalent Circuits

Electric drives based on traction linear-induction motors are used in industry and city transport. The main advantages of this electric drive are unrestricted acceleration and vehicle climbing angles, as well as ecological cleanliness. The development of high-speed design and analysis software tools for linear electric motors is thus becoming quite timely. The use of the finite-element method for solving field problems in a three-dimensional setting and dynamic vehicle-operation regimes is time-consuming. It is proposed to use a detailed magnetic equivalent circuit of a linear-induction-motor longitudinal section with the introduction of the Bolton coefficient to correct for the transverse-edge effect in a solid secondary element. Model features based on multilayer magnetic equivalent circuits are shown, and the effect of the number of layers on the designed motor-traction force is evaluated. When selecting an appropriate pole pitch-to motor gap ratio, a two-level equivalent circuit turns out to be suitable. The secondary element is represented in the model as a set of rectangular rods connected in parallel. The influence of the calculation method of the secondary rods’ motional EMF on the motor-traction-force accuracy is shown. The greatest error is observed in a low-slip region (when the motor passes into a generative braking regime) and the simplest spatial derivative of the magnetic flux. When the derivative calculation formula becomes more complicated, the indicated error sharply decreases. Another way to reduce the calculation error of the motional EMF in the secondary element circuit is to increase the number of these circuits by decreasing the width of the elementary rod. The prominence of the detailed magnetic equivalent-circuit method and convenience of online viewing should be noted.

Ordering transitions of weakly anisotropic hard rods in narrow slitlike pores.

The effect of strong confinement on the positional and orientational ordering is examined in a system of hard rectangular rods with length L and diameter D (L>D) using the Parsons-Lee modification of the second virial density-functional theory. The rods are nonmesogenic (L/D<3) and confined between two parallel hard walls, where the width of the pore (H) is chosen in such a way that both planar (particle's long axis parallel to the walls) and homeotropic (particle's long axis perpendicular to the walls) orderings are possible and a maximum of two layers is allowed to form in the pore. In the extreme confinement limit of H≤2D, where only one-layer structures appear, we observe a structural transition from a planar to a homeotropic fluid layer with increasing density, which becomes sharper as L→H. In wider pores (2D<H<3D) planar order with two layers, homeotropic order, and even combined bilayer structures (one layer is homeotropic, while the other is planar) can be stabilized at high densities. Moreover, first-order phase transitions can be seen between different structures. One of them emerges between a monolayer and a bilayer with planar orders at relatively low packing fractions.