Journal articles: 'Circular Beams'

1

Bandres, Miguel A., and Julio C. Gutiérrez-Vega. "Circular beams." Optics Letters 33, no. 2 (January 11, 2008): 177. http://dx.doi.org/10.1364/ol.33.000177.

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Florencio, Rafael, Daniel Martinez-de-Rioja, Eduardo Martinez-de-Rioja, Jose A. Encinar, Rafael R. Boix, and Vicente Losada. "Design of Ku- and Ka-Band Flat Dual Circular Polarized Reflectarrays by Combining Variable Rotation Technique and Element Size Variation." Electronics 9, no. 6 (June 12, 2020): 985. http://dx.doi.org/10.3390/electronics9060985.

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In this work circularly polarized flat reflectarray antennas are designed to work at downlink frequencies in Ku- and Ka-band. The design approach for circular polarization radiation combines both the variable rotation technique (VRT) and the element size variation technique (ESVT). The reflectarray element employed consists of a rotable split ring operating at 12 GHz (Ku-band) that surrounds two orthogonal sets of parallel dipoles of variable size operating at 20 GHz (Ka-band). Rotations of split rings and different sizes of dipoles are exploited as degrees of freedom by VRT and ESVT for designing focused beams dual band dual circular polarized reflectarrays. The split ring can be used to achieve single focused beams for circular polarization by VRT at 12 GHz, and the set of orthogonal dipoles can be used to achieve two focused beams for dual circular polarization by ESVT at 20 GHz. In this way, the reflectarray element has been used to design two flat dual band circularly polarized reflectarrays that generate three pencil beams either in the same direction or in different directions: one pencil beam with right-hand circular polarization (RHCP) at 12 GHz and two pencil beams with both RHCP and left-hand circular polarization (LHCP) at 20 GHz. The designed reflectarrays are carried out under local periodicity assumption by means of in-house electromagnetic software that applies the Method of Moments in the Spectral Domain. Validations of the in-house electromagnetic software show significant CPU time savings with respect to CPU time consumption provided by commercial software of general purpose as CST electromagnetics software. Numerical results of radiation patterns produced by the designed reflectarrays show efficiencies around 65% and a bandwidth of 6% for a main beam cross-polarization discrimination of 25 dB. The numerical results are satisfactorily validated by CST software and a tolerance errors study has been numerically carried out with acceptable results.

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Abdulrahman, Mazin B., Layth A. Al-Jaber, and Saba S. Hasan. "The Effect of Opening Size and Location on the Performance of Reinforced Concrete T-Beams under Pure Torque." Tikrit Journal of Engineering Sciences 27, no. 2 (March 15, 2020): 46–53. http://dx.doi.org/10.25130/tjes.27.2.06.

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In modern buildings, transverse openings are often used in order to pass the pipes of health services, electrical cables or air conditioning ducts and other prepuce. The presence of these openings leads to a weakening of the beam so it must work to investigate the behavior of these beams in order to know how the presence of openings affects beam resistance. In this research, the behavior of reinforced concrete T-beams with circular openings exposed to pure torsional moment is studied. The experimental program involves testing of five beams with same dimensions and reinforcements. One of them is solid beam and used as reference for comparison with other beams with an opening and the other four T- beams containing circular openings of deferent dimension(100 and 150) and location(Lc/2 and Lc/3). Practical results show that the Tbeam with circular openings of diameter (100mm) with different locations (Lc/2 and Lc/3), where Lc is the clear span of the beam, have an ultimate torsional capacity lower than that for solid beam by about (23% and 30%) respectively. The increase of the openings size causes a significant decrease in torsional capacity, where the beams with circular openings of diameter (150mm) with different locations (Lc/2 and Lc/3) have an ultimate torsional capacity lower than that for solid beam by about (56 % and 61%) respectively. Practical results show also that the presence of circular openings with diameter of 47% and 71% from the total depth increases the angle of twist significantly as compared with reference beam for the same applied torque level.

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Xu, Yiqing, and Guoquan Zhou. "Circular Lorentz–Gauss beams." Journal of the Optical Society of America A 36, no. 2 (January 14, 2019): 179. http://dx.doi.org/10.1364/josaa.36.000179.

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Hieu, Nguyen Tran. "Simplified design method and parametric study of composite cellular beam." Journal of Science and Technology in Civil Engineering (STCE) - NUCE 12, no. 3 (April 30, 2018): 34–43. http://dx.doi.org/10.31814/stce.nuce2018-12(3)-04.

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Nowadays, with the development of cutting and welding technologies, steel beams with regular circular openings, called cellular beams, have been widely used for construction. The cellular beams could be designed either as steel beam or composite beam when headed shear connectors connect concrete slab to top flange of steel beam. This paper presents a procedure to design cellular composite beams according to EN 1994-1-1. In addition, a parametric study is carried out to evaluate the influence of circular opening geometry to ultimate load and failure mode of a series of cellular composite beams. As a result, an optimal dimension of cellular beam is proposed. Article history: Received 28 February 2018, Revised 22 March 2018, Accepted 27 April 2018

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Baxy, Ajinkya, and Abhijit Sarkar. "Free vibrations of circular curved beams." MATEC Web of Conferences 211 (2018): 04006. http://dx.doi.org/10.1051/matecconf/201821104006.

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The study of free vibrations of curved beams has relevance in engineering applications like modeling turbo machinery blades, propellers, arch design, etc. Vibration characteristics of structures are generally evaluated using the Finite Element Method. The governing equations for the curved beam using the inextensional theory are available in the literature. These equations are solved analytically for two different boundary conditions, namely (a) simplysupported, (b) cantilever. The results obtained for all the cases are compared against the FEM simulation results. It is found that the present solutions are in agreement with the FEM solutions up to an opening angle of 40°.

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Pydah, Anup, and Aditya Sabale. "Closed-form exact solutions for thick bi-directional functionally graded circular beams." Multidiscipline Modeling in Materials and Structures 15, no. 1 (January 7, 2019): 79–102. http://dx.doi.org/10.1108/mmms-12-2017-0156.

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PurposeThere exists a clear paucity of models for curved bi-directional functionally graded (BDFG) beams wherein the material properties vary along the axis and thickness of the beam simultaneously; such structures may help fulfil practical design requirements of the future and improve structural efficiency. In this context, the purpose of this paper is to extend the analytical model developed earlier to thick BDFG circular beams by using first-order shear deformation theory which allows for a non-zero shear strain distribution through the thickness of the beam.Design/methodology/approachSmooth functional variations of the material properties have been assumed along the axis and thickness of the beam simultaneously. The governing equations developed have been solved analytically for some representative determinate circular beams. In order to ascertain the effects of shear deformation in these structures, the total strain energy has been decomposed into its bending and shear components and the effects of the beam thickness and the arch angle on the shear energy component have been studied.FindingsClosed-form exact solutions involving through-the-thickness integrals carried out numerically are presented for the bending of circular beams under the action of a variety of concentrated/distributed loads.Originality/valueThe results clearly indicate the importance of capturing shear deformation in thick BDFG beams and demonstrate the capability of tuning the response of these beams to fit a wide variety of structural requirements.

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Huang, T. W., C. T. Zhou, and X. T. He. "Self-shaping of a relativistic elliptically Gaussian laser beam in underdense plasmas." Laser and Particle Beams 33, no. 2 (April 28, 2015): 347–53. http://dx.doi.org/10.1017/s026303461500018x.

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AbstractSelf-shaping and propagation of intense laser beams of different radial profiles in plasmas is investigated. It is shown that when a relativistic elliptically Gaussian beam propagates through an underdense plasma, its radial profile will self-organize into a circularly symmetric self-similar smooth configuration. Such self-similar propagation can be attributed to a soliton-like structure of the laser pulse. The anisotropic electron distribution results in a circular electric field that redistributes the electrons and modulates the laser pulse to a circular radial shape.

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Safdar, Shakeel, Lin Li, M. A. Sheikh, and Zhu Liu. "An Analysis of the Effect of Laser Beam Geometry on Laser Transformation Hardening." Journal of Manufacturing Science and Engineering 128, no. 3 (December 6, 2005): 659–67. http://dx.doi.org/10.1115/1.2193547.

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The effect of transformation hardening depends upon both heating and cooling rates. It is desirable to have a slow heating rate and a rapid cooling rate to achieve full transformation. To date laser transformation hardening has been carried out using circular or rectangular beams which result in rapid heating and cooling. Although the use of different beam intensity distributions within the circular or rectangular laser beams has been studied to improve the process, no other beam geometries have been investigated so far for transformation hardening. This paper presents an investigation into the effects of different laser beam geometries in transformation hardening. Finite element modeling technique has been used to simulate the steady state and transient effects of moving beams in transformation hardening of EN 43A steel. The results are compared with experimental data. The work shows that neither of the two commonly used beams, circular and rectangular, are optimum beam shapes for transformation hardening. The homogenization temperature exceeds the melting point for these beam shapes for the usual laser scanning speeds and power density. Triangular beam geometry has been shown to produce the best thermal history to achieve better transformation and highest hardness due to slower heating without sacrificing the processing rate and hardening depths.

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Ni, Yongzhou, Yimin Zhou, Guoquan Zhou, and Ruipin Chen. "Characteristics of Partially Coherent Circular Flattened Gaussian Vortex Beams in Turbulent Biological Tissues." Applied Sciences 9, no. 5 (March 7, 2019): 969. http://dx.doi.org/10.3390/app9050969.

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The characteristics of partially coherent circular flattened Gaussian vortex beams in turbulent biological tissues are investigated, and the analytical formula for the cross-spectral density of this beam is derived. According to the cross-spectral density matrix, the average intensity and degree of polarization can be obtained. By numerical simulation, the distributions of the normalized average intensity and degree of polarization of partially coherent circular flattened Gaussian vortex beams are demonstrated on the research plane of turbulent biological tissues. The effects of the two beam parameters, the topological charge, the two transverse coherent lengths, and the structural constant of biological turbulence on the normalized average intensity and degree of polarization are analyzed. This study is of great significance for the potential application of partially coherent circular flattened Gaussian vortex beams in medical imaging and medical diagnosis.

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11

Silverman, I. K. "FLEXURAL VIBRATIONS OF CIRCULAR BEAMS." Journal of Sound and Vibration 210, no. 5 (March 1998): 661–72. http://dx.doi.org/10.1006/jsvi.1997.1340.

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12

Teng, Houan, Yixian Qian, Yanping Lan, and Yiming Cai. "Abruptly autofocusing circular swallowtail beams." Optics Letters 46, no. 2 (January 7, 2021): 270. http://dx.doi.org/10.1364/ol.415709.

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13

Du, Yongzhao, Yuqing Fu, and Chaoying Zheng. "Beam qualityM2factor matrix for non-circular symmetric laser beams." Laser Physics 27, no. 2 (December 20, 2016): 025001. http://dx.doi.org/10.1088/1555-6611/27/2/025001.

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14

Al-Ansari, Mohammed Salem, and Muhammad Shekaib Afzal. "Simplified Irregular Beam Analysis and Design." Civil Engineering Journal 5, no. 7 (July 21, 2019): 1577–89. http://dx.doi.org/10.28991/cej-2019-03091354.

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This paper presents simple method to estimate the strength design of reinforced concrete beam sections based on structural safety and reliability. Irregular beam shaped sections are commonly used nowadays in the construction industry. This study reveals the simplified method to analyze and design the different irregular shaped beam sections. In this study, the selected irregular beam shaped sections are divided mainly into three groups, beams with straight edges, beams with sloped edges and circular beams. Each group contains the most commonly used beam shaped sections in that category. Six beams sections (B-1 to B-6) are selected for group-1 whereas five beam sections (B-7 to B-11) and a circular beam section (B-12) are chosen for group 2 and 3 respectively. Flexural beam formulas for three groups of reinforced concrete beams are derived based on section geometry and ACI building code of design. This study also analyzed numerical examples for some of the sections in each group category using the proposed simplified method to determine the strength design of the irregular beams. The results obtained using simplified method for all of the three groups are compared with the finite element software (SAP v2000). The percentage difference of simplified method with the finite element software ranges within 5% to 10%. This makes the simplified method for irregular shaped beam sections quite promising.

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Zhang, Yuan, Bingyan Wei, Sheng Liu, Peng Li, Xin Chen, Yunlong Wu, Xian’an Dou, and Jianlin Zhao. "Circular Airy beams realized via the photopatterning of liquid crystals [Invited]." Chinese Optics Letters 18, no. 8 (2020): 080008. http://dx.doi.org/10.3788/col202018.080008.

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Gao, Penghui, Lu Bai, and Jinlu Li. "Comparison of propagation properties of circular edge dislocation beams and circular−linear edge dislocation beams." OSA Continuum 3, no. 11 (October 20, 2020): 2997. http://dx.doi.org/10.1364/osac.408827.

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Al-Bayati, Nabeel A., Dhiyaa H. Muhammad, and Nawfal A. Abdul Jabbar. "Retrofitting of SCC Deep Beams With Circular Openings Using CFRP." Engineering and Technology Journal 39, no. 7 (July 25, 2021): 1092–104. http://dx.doi.org/10.30684/etj.v39i7.74.

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The main objectives of this study are: encouraging the production and use of self-compacting concrete, use of materials which are lightweight, easy to use, and highly efficient in the retrofitting of reinforced concrete buildings. Six deep beams specimens (L= length of 1400mm, h= height of 400mm, and b= width of 150mm) were cast using self-compacting concrete. The location of the openings is in the middle of assumed load path. Five patterns were adopted to arrange carbon fiber reinforced polymer (CFRP) strips. The cylinder compressive strength of the concrete was approximately equal for all beams and was about (44 MPa) at 28 days age. All the beams have the same steel reinforcement for shear and flexure. There have been many tests for fresh and hardened concrete. The reinforced concrete deep beams were tested up to (60%) of the ultimate load of control beams to simulate degree of damage, and then released the load. After that, the beams were retrofitted using (CFRP) strips, and then the beams were tested to failure. The study was focused on determining the vertical mid-span deflection, ultimate load, the load that causes first shear and flexural cracks, and mode of failure. The results showed that, the best increase in the ultimate failure load was (27.27%) and achieved using the inclined strips pattern and the pattern of vertical and horizontal strips together. Reduction in the deflection values for the retrofitted beams compared to the control beam by about (12-13%) due to restrictions imposed by CFRP strips and the...

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Al-Bayati, Nabeel A., Bassman R. Muhammed, and Muroj F. Oda. "Effect of Shear Span to Effective Depth Ratio on the Behavior of Self-Compacting Reinforced Concrete Deep Beams Containing Openings Strengthened with CFRP." Association of Arab Universities Journal of Engineering Sciences 26, no. 1 (March 31, 2019): 1–9. http://dx.doi.org/10.33261/jaaru.2019.26.1.001.

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Results of test on seven simply supported self-compacting reinforced concrete deep beams, including six of these beams containing circular openings in center of load path are reported in this paper. The objective of the tests was determined the influence of, changing shear span to effective depth ratio a/d, the existence of circular openings in shear span and using inclined strips of carbon fiber polymer (CFRP) on behavior of deep beams. The general trend in crack pattern, the load-deflection response, and the mode of failure of reinforced SCC deep beams were also investigated. All specimens had the same geometry, details of the flexure and shear reinforcement in both vertical and horizontal directions and they were tested under symmetrical two-point loads up to failure. The experimental results revealed that the web openings within shear spans caused an important reduction in the deep beam capacity by 50% when compared with the corresponding solid beam. The increase a/d ratio from 0.8 to 1.2 decreases the ultimate load by 21.7% and 22.5 % for the reference unstrengthened beam and strengthened beam, respectively, also it was found that the externally inclined CFRP strips in deep beams increased the ultimate strength up to 39.5%, and enhanced the stiffness of deep beams with openings.

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Teixeira, P. W. G. N., C. E. M. Maffei, and M. C. Guazzelli. "Shear strength of reinforced concrete circular cross-section beams." Revista IBRACON de Estruturas e Materiais 5, no. 6 (December 2012): 781–97. http://dx.doi.org/10.1590/s1983-41952012000600004.

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A proposed adequation of NBR 6118, Item 7.4, related to shear strength of reinforced concrete beams is presented with aims to application on circular cross-section. The actual expressions are most suitable to rectangular cross-section and some misleading occurs when applied to circular sections at determination of VRd2, Vc and Vsw, as consequence of bw (beam width) and d (effective depth) definitions as well as the real effectiveness of circular stirrups. The proposed adequation is based on extensive bibliographic review and practical experience with a great number of infrastructure elements, such as anchored retaining pile walls, where the use of circular reinforced concrete members is frequent.

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Khalaf, Haidar Abdul Wahid, and Amer Farouk Izzet. "Performance of Reinforced Concrete Beams with Multiple Openings." Key Engineering Materials 857 (August 2020): 162–68. http://dx.doi.org/10.4028/www.scientific.net/kem.857.162.

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The present investigation focuses on the response of simply supported reinforced concrete rectangular-section beams with multiple openings of different sizes, numbers, and geometrical configurations. The advantages of the reinforcement concrete beams with multiple opening are mainly, practical benefit including decreasing the floor heights due to passage of the utilities through the beam rather than the passage beneath it, and constructional benefit that includes the reduction of the self-weight of structure resulting due to the reduction of the dead load that achieves economic design. To optimize beam self-weight with its ultimate resistance capacity, ten reinforced concrete beams having a length, width, and depth of 2700, 100, and 400 mm, respectively were fabricated and tested as simply supported beams under one incremental concentrated load at mid-span until failure. The design parameters were the configuration and size of openings. Three main groups categorized experimental beams comprise the same area of openings and steel reinforcement details but differ in configurations. Three different shapes of openings were considered, mainly, rectangular, parallelogram, and circular. The experimental results indicate that, the beams with circular openings more efficient than the other configurations in ultimate load capacity and beams stiffness whereas, the beams with parallelogram openings were better than the beams with rectangular openings. Commonly, it was observed that the reduction in ultimate load capacity, for beams of group I, II, and III compared to the reference solid beam ranged between (75 to 93%), (65 to 93%), and (70 to 79%) respectively.

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Biggs, James D. "Meridional Compression of Radio Pulsar Beams." International Astronomical Union Colloquium 128 (1992): 22–25. http://dx.doi.org/10.1017/s0002731600154691.

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AbstractWe have studied the radio pulsar emission beam assuming a) a magnetic dipole field geometry and b) that the beam geometry is defined by the field lines that are not contained within the light cylinder. In general, the beam is compressed in the meridional direction. When the magnetic and rotation axes are aligned the beam is circular and as, the angle between these axes increases, the ratio of meridional to longitudinal dimension decreases monotonically to the minimum value 0.62 when the axes are orthogonal. This beam shape is thus consistent with that inferred from the study of circular polarization in average pulse profiles by Radhakrishnan and Rankin. Evidence for meridional compression is also found in the extensive observational study of Lyne and Manchester (1988).The beam evolution was determined using this data set, the beamwidth being found proportional to P–1/2, where P is the pulsar period. This relation implies that the more rapidly rotating pulsars should have larger beams, and this should aid in their detection. The more numerous, slower pulsars should have somewhat smaller beams than previously determined. This implies that the pulsar birthrate is probably close to the highest current estimates (1 in 25yr).

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Dubigeon, S. "Torsional stiffness for circular orthotropic beams." AIAA Journal 30, no. 9 (September 1992): 2355–57. http://dx.doi.org/10.2514/3.11232.

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Song, Qilong, Yang Wang, Kai Liu, Jie Zhang, and Yang Wang. "Beam steering for OAM beams using time‐modulated circular arrays." Electronics Letters 54, no. 17 (August 2018): 1017–18. http://dx.doi.org/10.1049/el.2018.5386.

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BALLAGH, R. J., and A. W. McCORD. "SPATIAL SEPARATION OF POLARIZATION COMPONENTS BY NONLINEAR BEAM RESHAPING IN A J=1 TO J=0 MEDIUM." Journal of Nonlinear Optical Physics & Materials 01, no. 02 (April 1992): 393–420. http://dx.doi.org/10.1142/s0218199192000194.

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The diffractive reshaping that circularly polarized light beams undergo when coupled in a medium of homogenously broadened J=1→J=0 atoms is shown to be sensitively dependent on applied magnetic fields. In zero field, an elliptically polarized beam will retain its polarization everywhere in space, but a small longitudinal magnetic field can cause the beam to break up into spatially distinct regions of pure circular polarization. The beam behavior can be understood in terms of an encoding/diffraction sequence. An analytic solution for the atomic response function reveals the important roles played by transverse and longitudinal optical pumping.

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MALEKZADEH, P., M. R. GOLBAHAR HAGHIGHI, and M. M. ATASHI. "OUT-OF-PLANE FREE VIBRATION ANALYSIS OF FUNCTIONALLY GRADED CIRCULAR CURVED BEAMS SUPPORTED ON ELASTIC FOUNDATION." International Journal of Applied Mechanics 02, no. 03 (September 2010): 635–52. http://dx.doi.org/10.1142/s175882511000069x.

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As a first endeavor, the out-of-plane free vibration analysis of thin-to-moderately thick functionally graded (FG) circular curved beams supported on two-parameter elastic foundation is presented. The formulation is derived based on the first-order shear deformation theory (FSDT), which includes the effects of shear deformation and rotary inertia due to both torsional and flexural vibrations. The material properties are assumed to be graded in the direction normal to the plane of the beam curvature. The differential quadrature method (DQM), as an efficient and accurate method, is employed to discretize the equations of motion and the related boundary conditions. In order to assure the accuracy of the formulation and the method of solution, convergence behavior of the nondimensional natural frequencies is examined for FG circular curved beams and comparison studies with those of isotropic curved beams, available in the literature, are performed. The effects of the elastic foundation coefficients, boundary conditions, the material graded index and different geometrical parameters on the natural frequency parameters of the FG circular curved beams are investigated. The new results can be used as benchmark solutions for future research works.

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Wang, Zhongmin, and Rongrong Li. "Transverse Vibration of Rotating Tapered Cantilever Beam with Hollow Circular Cross-Section." Shock and Vibration 2018 (2018): 1–14. http://dx.doi.org/10.1155/2018/1056397.

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Problems related to the transverse vibration of a rotating tapered cantilever beam with hollow circular cross-section are addressed, in which the inner radius of cross-section is constant and the outer radius changes linearly along the beam axis. First, considering the geometry parameters of the varying cross-sectional beam, rotary inertia, and the secondary coupling deformation term, the differential equation of motion for the transverse vibration of rotating tapered beam with solid and hollow circular cross-section is derived by Hamilton variational principle, which includes some complex variable coefficient terms. Next, dimensionless parameters and variables are introduced for the differential equation and boundary conditions, and the differential quadrature method (DQM) is employed to solve this differential equation with variable coefficients. Combining with discretization equations for the differential equation and boundary conditions, an eigen-equation of the system including some dimensionless parameters is formulated in implicit algebraic form, so it is easy to simulate the dynamical behaviors of rotating tapered beams. Finally, for rotating solid tapered beams, comparisons with previously reported results demonstrate that the results obtained by the present method are in close agreement; for rotating tapered hollow beams, the effects of the hub dimensionless angular speed, ratios of hub radius to beam length, the slenderness ratio, the ratio of inner radius to the root radius, and taper ratio of cross-section on the first three-order dimensionless natural frequencies are more further depicted.

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Su, Changjiang, Yanqun Liu, Leilei Liu, Mei Yang, Hongxin Zhao, and Xiaoxing Yin. "Experimental Evaluation of Multipath Mitigation in TDOA-Based Indoor Passive Localization System Using A Beam Steering Broadband Circular Polarization Antenna." Electronics 7, no. 12 (December 1, 2018): 362. http://dx.doi.org/10.3390/electronics7120362.

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An experimental evaluation of multipath mitigation using a beam steering broadband circular polarization antenna (BSBCPA) in indoor passive localization system based on time differences of arrival (TDOA) is presented in this paper. The BSBCPA consists of a beam switch network, four identical hexagon patch elements and their respective feeding networks. By controlling the states of a radio frequency (RF) switch in the beam switch network, four steering circular polarization beams can be excited separately for azimuth omnidirectional coverage. Combining the spatial selectivity of steering beams and circular polarization in the BSBCPA, the positioning inaccuracy from indoor multipath propagation can be mitigated. In two different indoor environments with line of sight (LOS), complex multipath, when transmitting a 20 MHz bandwidth signal in WLAN, the 2D positioning mean error obtained is 0.7 m and 0.82 m, respectively. Compared with conventional omnidirectional linear polarization antenna (OLPA), the BSBCPA can at least improve positioning accuracy by 51%. The experimental results show that the proposed BSBCPA can significantly mitigate multipath propagation for TDOA-based indoor passive localization.

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Kravchuk, V. A. "Free oscillations of steel beams prestressed by wall stretching." Вестник гражданских инженеров 17, no. 6 (2020): 97–103. http://dx.doi.org/10.23968/1999-5571-2020-17-6-97-103.

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The article presents the study results of the impact of steel beam prestressing by wall stretching on changes in the circular frequency, frequency, period, and number of oscillations per minute for free oscillation, and for oscillation taking into account the resistance forces. The forced oscillations of the beam under impulse loading are investigated. There has been carried out a comparative analysis of the dynamic parameters of prestressed beams and conventional beams of equal cross-section with the same load-bearing capacity parameters. The analysis results of the influence of resistance forces on the oscillation process in prestressed beams and conventional beams are submitted. There has been established the time of oscillations damping in the compared beams at free oscillation, taking into account the resistance forces.

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Al-Bayati, Nabeel, Bassman Muhammad, and Murooj Faek. "Strengthening of self-compacting reinforced concrete deep beams containing circular openings with CFRP." MATEC Web of Conferences 162 (2018): 04015. http://dx.doi.org/10.1051/matecconf/201816204015.

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This paper shows the behavior of reinforced self-compacting concrete deep beams with circular openings strengthened in shear with various arrangements of externally bonded Carbon Fibre Reinforced Polymer (CFRP). Six simply supported deep beams were constructed and tested under two points load up to the failure for this purpose. All tested beams had same geometry, compressive strength, shear span to depth ratio, main flexural and web reinforcement. The variables considered in this study include the influence of fiber orientation, utilizing longitudinal CFRP strips with vertical strips and area of CFRP. The test results indicated that the presence of the circular openings in center of load path reduce stiffness and ultimate strength by about 50% when compared with solid one, also it was found that the externally bonded CFRP can significantly increase the ultimate load and enhance the stiffness of deep beam with openings.

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Pritykin, Alexej I. "State of Stress of Castellated Beams with Circular Apertures under Distributed Load and Pure Bending." Materials Science Forum 974 (December 2019): 521–28. http://dx.doi.org/10.4028/www.scientific.net/msf.974.521.

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The regularities of stress distribution in perforated beams with circular apertures under distributed load and pure bending. Such beams are made of different materials: carbon fiber is used in aircraft for these purposes, and steel is used in construction. Beams with different perforation parameters were considered and an empirical relation was obtained for equivalent von Mises stresses in castellated beams near the apertures’ outlines based on the analysis of FEM calculations. In this paper, beams made of C345 steel were considered. It is established that the maximum values of equivalent stresses near apertures under different loading types vary along the beam length in proportion to the values of the bending moment. The values of stress concentration coefficients for the pure bending are determined depending on the perforation parameters. The acceptability of the obtained empirical dependencies for equivalent stresses was verified using the FEM calculations based on the ANSYS software package. There is a good correlation between the results of FEM calculations and empirical dependence.

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Lee, Sen Yung, and Jeng Chung Chao. "In-Plane Vibrations of Nonuniform Circular Beams." AIAA Journal 39, no. 3 (March 2001): 543–46. http://dx.doi.org/10.2514/2.1344.

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Kotlyar, V. V., A. A. Kovalev, and M. A. Volynov. "VECTORIAL VORTEX HANKEL BEAMS WITH CIRCULAR POLARIZATION." Computer Optics 40, no. 6 (January 1, 2016): 765–71. http://dx.doi.org/10.18287/2412-6179-2016-40-6-765-771.

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Cervantes, M. A., A. A. Lipovka, and M. M. Tavares. "Circular aperture diffraction of multiple interfering beams." Optics Communications 185, no. 4-6 (November 2000): 233–37. http://dx.doi.org/10.1016/s0030-4018(00)01010-5.

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Arnau, J. V., A. M. Aliaga, and D. Sáez. "Non-circular rotating beams and CMB experiments." Astronomy & Astrophysics 382, no. 3 (February 2002): 1138–50. http://dx.doi.org/10.1051/0004-6361:20011681.

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Lee, Sen Yung, and Jeng Chung Chao. "In-plane vibrations of nonuniform circular beams." AIAA Journal 39 (January 2001): 543–46. http://dx.doi.org/10.2514/3.14768.

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Siguenza-Torres, Anibal, and Julio C. Gutiérrez-Vega. "Creation operators for Cartesian and circular beams." Journal of the Optical Society of America A 33, no. 5 (April 8, 2016): 832. http://dx.doi.org/10.1364/josaa.33.000832.

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Zhang, Jinggui. "Propagation Characteristics of Chirped Circular Airy Beams." IEEE Journal of Quantum Electronics 53, no. 2 (April 2017): 1–6. http://dx.doi.org/10.1109/jqe.2017.2657326.

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Kadlimatti, Ravi, and Patanjali V. Parimi. "Millimeter-Wave Nondiffracting Circular Airy OAM Beams." IEEE Transactions on Antennas and Propagation 67, no. 1 (January 2019): 260–69. http://dx.doi.org/10.1109/tap.2018.2876713.

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Haselhoff, Eltjo H., and Gerard J. Ernst. "Space charge effects in circular electron beams." Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment 318, no. 1-3 (July 1992): 295–300. http://dx.doi.org/10.1016/0168-9002(92)91069-l.

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Babu, J., and G. S. N. Raju. "Generation of cosecant beams from circular arrays." AEU - International Journal of Electronics and Communications 67, no. 2 (February 2013): 81–87. http://dx.doi.org/10.1016/j.aeue.2012.03.019.

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Babamohammadi, Sajjad, Nicholas Fantuzzi, and Graziano Lonardi. "Mechanical assessment of hollow-circular FRP beams." Composite Structures 227 (November 2019): 111313. http://dx.doi.org/10.1016/j.compstruct.2019.111313.

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Rashed, Yasser. "Dosimetric characterization of circular collimator radiosurgical beams." Research in Oncology 3, no. 1 (January 1, 2007): 54–60. http://dx.doi.org/10.21608/resoncol.2007.377.

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Huang, Yong. "Bending and free vibrational analysis of bi-directional functionally graded beams with circular cross-section." Applied Mathematics and Mechanics 41, no. 10 (September 12, 2020): 1497–516. http://dx.doi.org/10.1007/s10483-020-2670-6.

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Abstract The bending and free vibrational behaviors of functionally graded (FG) cylindrical beams with radially and axially varying material inhomogeneities are investigated. Based on a high-order cylindrical beam model, where the shear deformation and rotary inertia are both considered, the two coupled governing differential motion equations for the deflection and rotation are established. The analytical bending solutions for various boundary conditions are derived. In the vibrational analysis of FG cylindrical beams, the two governing equations are firstly changed to a single equation by means of an auxiliary function, and then the vibration mode is expanded into shifted Chebyshev polynomials. Numerical examples are given to investigate the effects of the material gradient indices on the deflections, the stress distributions, and the eigenfrequencies of the cylindrical beams, respectively. By comparing the obtained numerical results with those obtained by the three-dimensional (3D) elasticity theory and the Timoshenko beam theory, the effectiveness of the present approach is verified.

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Somolinos, Florencio, González, and Cátedra. "Multi-Beam Circular Polarized Reflectarray on Parabolic Reflector by Variable Rotation Technique." Applied Sciences 9, no. 13 (June 29, 2019): 2659. http://dx.doi.org/10.3390/app9132659.

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Multi-beams antennas are currently being used for direct broadcast satellite, personal communication satellite, military communication satellite, and high-speed internet applications. In this work, a circularly polarized (CP) multi-spot beam satellite parabolic reflectarray antenna is designed to provide six spot beams at 19.7 GHz. For this purpose, an easy technique to compute the required phase shifts to produce two focused beams in specular directions for a CP parabolic reflectarray is proposed. These required phase shifts are added to the reflected fields by the variable rotation of the reflectarray elements printed on the surface of a parabolic antenna which are fed by a dual-CP feed-horn. For this purpose, a reflectarray cell made of a conductive cross embedded in a grounded multilayered substrate is optimized to produce very linear phase-shift and low cross-polarization level. To demonstrate the multibeam capacity, a 1.8-meter offset parabolic reflectarray made of the optimized reflectarray element was designed to generate six focused beams in dual-CP with three dual-CP feed-horns. The six main spots fulfill the typical multi spot satellite requirement with angular separation less than 0.56°, 0.4 dB loss in the gain, and cross-polarization level below 35 dB with respect to the maximum of radiation.

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Abdul-Razzaq, Khattab Saleem, Abdullah A. Talal, Wisam H. Khaleel, and Yahyia M. Hameed. "Reinforced Concrete Semi Circular Deep Beams - Finite Element Investigation." Diyala Journal of Engineering Sciences 14, no. 1 (March 15, 2021): 130–47. http://dx.doi.org/10.24237/djes.2021.14112.

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This paper represents a parametric study utilizing finite element analysis for twenty-five reinforced concrete semi-circular deep beams. The parameters that were taken into consideration in the current work are radius, height, width, concrete compressive strength and number of supports. It is found that decreasing radius of beam by 16-66% leads to decrease the midspan positive moment, support negative moment, torsional moment and midspan deflection by about 0.3-20%, 2.4-25%, 2-24% and 29-85%, respectively, while the load capacity increases by about 23-158%. The midspan positive moment, support negative moment, torsional moment and load capacity increase by about 20-682%, 20-81%, 20-81% and 21-84%, respectively, whereas midspan deflection decreases by 7-17% when the beam height increases by about 16-66%. The positive moment, negative moment, torsional moment and load capacity increases by about 43-197%, 40-185%, 29-187% and 46-214%, respectively, whereas deflection decreases by about 1.4-3.3% when the beam width increases by about 16-66%. The positive moment, negative moment, torsional moment and load capacity increases by about 10-84%, 9-77%, 9-79% and 11-92%, respectively, whereas deflection decreases by about 0.1-0.5% when the compressive strength increases by 20-220%. Finally, it is found that the positive moment increases by about 36-47% when number of supports increased by 33-66%, while the negative moment increases by about 16-31% when number of supports decreases by 14-29%, whereas the torsional moments and deflection decreases by about 6-55% and 37-84%, respectively when number of supports increases by 33-133%, while load capacity increases by 156-969% when number of support increases by 33-133%.

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Lisiecki, A. "Comparison of Titanium Metal Matrix Composite Surface Layers Produced During Laser Gas Nitriding of Ti6Al4V Alloy by Different Types of Lasers." Archives of Metallurgy and Materials 61, no. 4 (December 1, 2016): 1777–84. http://dx.doi.org/10.1515/amm-2016-0287.

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Abstract The article presents the results of a comparative study of the nitriding process of titanium alloy substrate using two lasers with different characteristics of laser beams. One of the applied lasers was a high power diode laser emitting at a dominant wavelength of 808 nm, with a rectangular laser beam spot, and multimode energy distribution across the spot. The second laser was a solid state Yb:YAG disk laser emitting at a wavelength of 1.03 μm, with a circular beam spot, characterized by near Gaussian energy distribution across the spot. In a case of both lasers single stringer beads with a similar width and at similar energy input were produced. As a result of melting of the substrate with a laser beam in a pure gaseous nitrogen atmosphere composite surface layers with in situ precipitated titanium nitrides embedded in the metallic matrix of titanium alloy were produced, in both cases. However, the surface topography and structure is different for the surface layers produce by different lasers at the same processing parameters and width of laser beams.

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AL-Dhabyani, Ahmed Ali, and Abdulwahab AL-Ansi. "Numerical Analysis for Reinforced Concrete Beams with Circular Openings in Flexural and Shear Zones Strengthened by Steel Plates." Journal of Science and Technology 23, no. 2 (December 16, 2018): 31–48. http://dx.doi.org/10.20428/jst.23.2.2.

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In the modern building construction, openings in beams are necessary to accommodate several service pipes and ducts. Due to these openings, high stress concentration occurs at its edges. Local cracks also appear around the openings as a result of the reduction in the beam stiffness, the load carrying capacity and the shear capacity. There are many studies which were conducted to develop and test different strengthening methods for the beams opining to increase the ultimate load capacity of the beams. However, from a practical point of view, it is better to have one strengthening method having the same specifications to be used in both; shear and flexural zones for circular opining beams in buildings. In spite of the prior studies, no study has addressed this issue; therefore, there is a need to study such a case. In this paper, an analytical study was conducted to investigate the behavior of the reinforced concrete (RC) beams with circular openings in flexural and shear zones strengthened by steel plates. A 3D FE modeling (ABAQUS 6.12) software was used to simulate five different specimens of RC beams. The study results showed that when the openings were strengthened by steel plates, the ultimate load carrying capacity increased, but the deflection was decreased when compared to the openings without strengthening. In addition, the model reliability was verified via good agreements between the experimental and numerical results.

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Griso, Georges, Larysa Khilkova, Julia Orlik, and Olena Sivak. "Asymptotic Behavior of Stable Structures Made of Beams." Journal of Elasticity 143, no. 2 (February 5, 2021): 239–99. http://dx.doi.org/10.1007/s10659-021-09816-w.

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AbstractIn this paper, we study the asymptotic behavior of an $\varepsilon $ ε -periodic 3D stable structure made of beams of circular cross-section of radius $r$ r when the periodicity parameter $\varepsilon $ ε and the ratio ${r/\varepsilon }$ r / ε simultaneously tend to 0. The analysis is performed within the frame of linear elasticity theory and it is based on the known decomposition of the beam displacements into a beam centerline displacement, a small rotation of the cross-sections and a warping (the deformation of the cross-sections). This decomposition allows to obtain Korn type inequalities. We introduce two unfolding operators, one for the homogenization of the set of beam centerlines and another for the dimension reduction of the beams. The limit homogenized problem is still a linear elastic, second order PDE.

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Abdulrahman, Mazin B., and Husham M. Rashid. "Repairing of Reactive Powder Concrete T-Beams Containing Web Opening by CFRP Strips." TJES Vol26 No.1 2019 26, no. 1 (March 1, 2019): 9–19. http://dx.doi.org/10.25130/tjes.26.1.02.

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In modern buildings, transverse openings are often used beams for the purpose of supplying and service pipes. Due to the presence of the openings in the concrete beams lead to the formation of cracks around the openings due to the stresses concentration in a small area above and below of the opening. The repairing, maintenance, and upgrading of structural members, are maybe one of the most pivotal problems in civil engineering applications. In this research, an experimental work is conducted to study the behavior of the reinforced RPC T-beams that containing openings and repair this beams using CFRP strips. The Experimental program of the present study includes two parts, the first part includes testing of seven reinforced reactive powder concrete RPC T-beams, which casted and tested, one beam is without opening as a reference beam and the rest, were provided with an opening. and these beams are divided into two groups. The first group was used to study the effect of the openings shape (circular and square) and the second group was used to study the effect of the openings locations, which consists three locations (Lc/2, Lc/3 and Lc/4).These are measured from the support center to the openings center. While the second part including a repaired all beams in the first part the using carbon fiber polymer. The test results indicated that the presence of openings in the beams web caused a reduction in the reinforced RPC T-beams ultimate load carrying capacity with about (10-55)%, Also lead to increasing in deflection compared to control beam before repairing at same loading. Studying the shape effect showed that the beams with square openings have average ultimate load carrying capacity lower by 36% compared with the control beams.While beams with containing circular openings have average ultimate load carrying capacity lower 29%. From the test results, it could be concluded that the presence of the openings in the shear region led to a decrease in ultimate load carrying capacity a about 38% to 49% for opening of opening at (Lc/3 and Lc/4) respectively. While the presence of openings in the flexural region led to a decrease in the ultimate load carrying capacity rate of 11%. Related to the repairing study part it was found that the average ultimate load carrying capacity for repairing beams was 103% compared with the not repaired beams.

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Liao, Wen Yuan, Dong Hua Zhou, and Long Qi Li. "Analysis of Composite Beam with Different Web Openings." Advanced Materials Research 919-921 (April 2014): 15–18. http://dx.doi.org/10.4028/www.scientific.net/amr.919-921.15.

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In order to investigate the bearing behavior of composite beam with different web openings. Six composite beams were analyzed by using the finite element program ANSYS and the shape of openings was different. The results show that the shape of opening has a significant influence on the bearing capacity and deformation capacity of composite beams with web openings. Because stress concentration is relatively small, the force performance of circular web opening is more reasonable and has the largest bearing capacity and deformation capacity.

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Journal articles on the topic 'Circular Beams'

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