Journal articles on the topic 'Beam'
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1
Sharma, Prerana. "Cross Focusing of two Coaxial Gaussian Beams with Relativistic and Ponderomotive Nonlinearity." Zeitschrift für Naturforschung A 67, no. 1-2 (February 1, 2012): 10–14. http://dx.doi.org/10.5560/zna.2011-0064.
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This paper presents the cross focusing of two high power lasers by taking off-axial contributions of the laser beams in a collisionless plasma. Due to relativistic and ponderomotive nonlinearities the two laser beams affect the dynamics of each other and cross focusing takes place. The expressions for the laser beam intensities by using the eikonal method are derived. The contributions of the r2 and r4 terms are incorporated. By expanding the eikonal and the other relevant quantities up to the fourth power of r, the solution of the pump laser beam is obtained within the extended paraxial ray approximation. Filamentary structures of the laser beams are observed due to the relativistic and the ponderomotive nonlinearity. The focusing of the laser beams is shown to become fast in the extended paraxial region. Using the laser beam and the plasma parameters, appropriate for beat wave processes, the filaments of the laser beams are studied and the relevance of these results to beat wave processes is pointed out.
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HUANG, YEN-CHIEH. "LASER BEAT-WAVE BUNCHED BEAM FOR COMPACT SUPERRADIANCE SOURCES." International Journal of Modern Physics B 21, no. 03n04 (February 10, 2007): 287–99. http://dx.doi.org/10.1142/s0217979207042069.
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A periodically bunched electron beam is useful for generating high-brightness electron superradiance. This paper studies the generation and acceleration of density-modulated electron beams from a photocathode electron gun driven by a laser beat wave. Computer simulation shows the feasibility of accelerating and preserving the density-modulated electron beam in an accelerator. This paper also details the implementation of a beat-wave laser system with a variable beat frequency for driving a photocathode electron gun.
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XIE, Hao, Xiaotong SUN, Yanqing MEN, Yongliang HUANG, and Yuxin CAO. "Study on failure mechanism of reinforced concrete beam based on cohesive zone model." Xibei Gongye Daxue Xuebao/Journal of Northwestern Polytechnical University 40, no. 1 (February 2022): 175–81. http://dx.doi.org/10.1051/jnwpu/20224010175.
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The problem of crack propagation in reinforced concrete beams is common in practical engineering. It is very important to correctly describe the law of crack propagation, the mechanism of fracture failure and the internal stress and deformation characteristics of the beams. Based on cohesive zone mode, the mechanical mechanism of fracture failure of 3D reinforced concrete beams under external load is studied in this paper. By comparing the numerical simulation with the experimental results of the reinforced concrete beam, the crack distribution, expansion law and failure mode of the reinforced concrete beam under the conditions of different reinforcement ratio and spiral stirrup inclination angle are investigated. The results show that: ①a small amount of reinforcement and a superfluous amount of reinforcement will make the reinforced concrete beam show the characteristics of brittle failure, while the moderate reinforcement ratio can give full play to the ductility of the reinforced concrete beam, which is easier to bear the load of the beam; ②when the inclination angle of spiral stirrup is about 80°, the bearing capacity of normal section and oblique section of the beam reach the maximum value.
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Lyu, Yu-Ting, Tsung-Pin Hung, Her-Chang Ay, Hsiu-An Tsai, and Yih-Cherng Chiang. "Evaluation of Laminated Composite Beam Theory Accuracy." Materials 15, no. 19 (October 6, 2022): 6941. http://dx.doi.org/10.3390/ma15196941.
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Carbon fiber-reinforced polymer (CFRP) has been widely implemented in electric vehicle bodies and aircraft fuselage structures. The purpose of CFRP is to reduce the weight and impart rigidity in the final product. A beam structure is typically used to bear the structural load, and the rigidity of the beam can be changed by arranging the laminated fibers at different angles. In this study, a composite I-beam is used as an example in engineering components. Because the theoretical model of the superimposed composite I-beam is established, the theoretical formula is based on the theoretical assumptions of the two-dimensional composite beam, and is combined with the traditional composite plate theory to analyze the maximum bending stress, strain, and deflection. During the theoretical derivation, it is assumed that the flanges of the I-beams are divided into narrow and wide flanges. The beams are considered as structures of beams and flatbeds. When a narrow flange is loaded in the side, the wide flange has no lateral deformation, and the lateral moments are neglected. Therefore, the accuracy of this formula needs to be verified. The purpose of this study is to verify the accuracy of theoretical solutions for the deflection and stress analysis of composite beams. A finite element analysis model is used as the basis for comparing the theoretical solutions. The results indicate that when the aspect ratio of the beam is >15, the theoretical solution will have better accuracy. Without the addition of the material, when 0° ply is placed on the outermost layer of the flange of the nonsymmetric beam, the effective rigidity of the beam is increased by 4–5% compared with the symmetrical beam. The accuracy range of the theoretical solution for the composite beams can be accurately defined based on the results of this study.
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Prasetyawati, Erlina, and Mochamad Solikin. "PERILAKU LENTUR PADA BALOK BETON SERAT BESI BERLUBANG MENERUS DI DAERAH TARIK." Wahana Teknik Sipil: Jurnal Pengembangan Teknik Sipil 26, no. 2 (December 1, 2021): 133. http://dx.doi.org/10.32497/wahanats.v26i2.3128.
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Concrete beams that receive a positive bending force, at the top will experience a compressive force while at the bottom receive a tensile force. The theory that reinforced concrete is a structural system where the steel or reinforcement in the concrete functions to withstand tension, then the concrete below the neutral line does not receive a compressive force but transmits a tensile force to the reinforcement. This study analyzes and reduces the area in the tensile area by continuously installing 2 inch diameter PVC pipes and adding fiber to the concrete. This reduction in area is expected to reduce weight and material savings without reducing its strength. This research was carried out with a sample of 28 days old concrete blocks with quality f'c = 21.04 MPa with dimensions of 12 cm x 18 cm x 250 cm, with 4Ø10 mm reinforcement with quality fy = 450 MPa. Concrete beams are made in 3 variations in the form of solid beams, hollow beams without fiber, hollow beams with fiber. Each variation has 2 samples. From the test results, all beams experienced flexural cracks which were characterized by cracks perpendicular to the beam axis and flexural strength behavior which the difference was not significant. From the three variations of this beam, it shows that the results of the hollow beam with the addition of fiber have a greater first crack load. The addition of fiber is able to slow down the cracks that occur and contribute to withstand tensile stresses so that the beam still has strength to bear the load even though cracks have occurred. Based on the calculation simulation, in order to equalize the strength of the hollow beam with fiber, the dimensions of the solid beam need to be enlarged so that the solid beam becomes more expensive. This shows that hollow beams with fiber are more economical than solid beams.
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KUMAR, RAJ, H. D. PANDEY, R. P. SHARMA, and M. KUMAR. "Relativistic cross-focusing of two coaxial Gaussian laser beams in a plasma." Journal of Plasma Physics 60, no. 4 (November 1998): 811–18. http://dx.doi.org/10.1017/s0022377898007132.
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The paper presents a paraxial theory of the relativistic cross-focusing of two coaxial Gaussian laser beams of different frequencies in a homogeneous plasma. We discuss the self-focusing of a weaker laser beam in the plasma due to the optical inhomogeneities introduced by another stronger copropagating laser beam. In the presence of the second stronger beam (Pcr21<P2<Pcr22), the plasma behaves as an oscillatory waveguide for the first, weaker, beam (P1<Pcr11) as it propagates in the plasma. When both the beams are strong (Pcr11,21<P1,2<Pcr12,22), the nonlinearities introduced by the relativistic effect are additive in nature, such that one beam can undergo oscillatory self-focusing and the other simultaneously defocusing, and vice versa. A comparison reveals that cross-focusing due to relativistic nonlinearity is possible for a wider range of powers of the laser pulses than is cross-focusing due to ponderomotive nonlinearity. Relativistic cross-focusing is important in plasma beat-wave excitation and collective laser particle accelerators.
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Mei, Lidan, Nan Guo, Hongliang Zuo, Ling Li, and Guodong Li. "Influence of the Force Arm on the Flexural Performance of Prestressed Glulam Beams." Advances in Civil Engineering 2021 (January 15, 2021): 1–16. http://dx.doi.org/10.1155/2021/8831406.
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In recent years, extensive attention has been drawn to prefabricated buildings, particularly wood construction. Glulam beams are the major supporting components of modern wood buildings. Since the force arm is the most critical indicator to evaluate the resistance moment of the glulam beam string structure, it is necessary to further study the influence of the force arm on the mechanical properties of the glulam beam string structure. We tested the flexural performance of 15 prestressed glulam beams, which were divided into two groups (A and B) to, respectively, research the influences of the string arm and the end arm on the bearing capacity, failure mode, stress distribution, and deformation performance of glulam beams. The results showed that when the height of the end arm remained constant and the string arm increased from 90 mm to 130 mm and 170 mm, the bearing capacity of the beam increased by 6.77% and 17.22%, respectively. Moreover, as the depth of the compression zone of the glued timber beam gradually increased, the failure mode of the beam changed from the brittle tension failure of the beam bottom to the ductile compression failure of the beam top. When the height of the string arm remained constant and the end arm increased from 10 mm to 30 mm and 50 mm, the bearing capacity of the beam increased by 4.27% and 8.13%, respectively. The beam had no significant change in the failure mode, while it could bear the stress more uniformly. Based on the experimental results and principles of equilibrium, moment equilibrium, and similar triangle, we calculated the ultimate bearing capacity of the glulam beam and proposed a design method for durable wood structures.
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Du, Huanhuan, Jianyou Pan, Huaxun Shen, and Jie Dong. "Numerical Analysis of Flexural Behavior of Prestressed Steel-Concrete Continuous Composite Beams Based on BP Neural Network." Computational Intelligence and Neuroscience 2022 (May 10, 2022): 1–10. http://dx.doi.org/10.1155/2022/5501610.
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Prestressed steel-concrete continuous composite beam (PCCB) is a kind of beam, which makes reinforced concrete slab and steel beam bear load and coordinate deformation through connectors such as studs. Prestressed steel-concrete continuous composite beam is a kind of transverse load-bearing composite member formed by prestressed technology on the basis of ordinary composite beam. Aiming at the flexural behavior of prestressed steel-concrete continuous composite beams, a three-dimensional finite element numerical analysis model is established, and the whole process of the test is simulated based on BP neural network. The calculated results are in good agreement with the test. Using this model, the mechanical deformation performance of prestressed steel-concrete continuous composite beam is further analyzed, and the effects of some parameters (steel beam strength grade, concrete strength grade, concrete slab thickness, and transverse reinforcement ratio) on the flexural performance of prestressed steel-concrete continuous composite beam are discussed, which provides a reference basis for engineering design.
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Cao, Zhong Liang, Yan Ding, Qing Ming Hu, and Qiang Guo. "Modal Analysis of the Gantry Milling and Boring Machine Tool Beam Based on FEM." Applied Mechanics and Materials 151 (January 2012): 424–28. http://dx.doi.org/10.4028/www.scientific.net/amm.151.424.
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Fixed beam gantry for large CNC boring and milling machine to bear the beams on the rail side apron, and other parts ram weight under weight and size of deformation produced a result of the assembly accuracy of less than standard, use three-dimensional modeling software UG and finite element analysis software ANSYS for dynamic beam gantry milling machine CNC beam three-dimensional modeling and modal analysis, based on weight and apron beams, the weight of ram and other components in relative deformation amplitude, and the gantry milling machine processing characteristics and overall design of the structural characteristics of machine tools, assembly of the beam is proposed to note some issues and some ways to solve the assembly size requirements, through finite element analysis of the deformation and comparing the actual measured value, the experiment proved data on-site assembly solution with a good theoretical support.
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Singh, Arvinder, and Naveen Gupta. "Beat wave excitation of electron plasma wave by coaxial cosh-Gaussian laser beams in collisional plasma." Laser and Particle Beams 33, no. 4 (July 14, 2015): 621–32. http://dx.doi.org/10.1017/s0263034615000646.
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AbstractThis paper presents a scheme for beat wave excitation of an electron plasma wave (EPW) by cross-focusing of two intense cosh-Gaussian (ChG) laser beams in an under dense collisional plasma. The plasma wave is generated on account of beating of two ChG laser beams of frequencies ω1 and ω2. Starting from Maxwell's equations, coupled differential equations governing the evolution of spot size of laser beams with distance of propagation have been derived by using Moment theory approach in Wentzel–Kramers–Brillouin approximation. The collisional nonlinearity depends not only on the intensity of first laser beam, but also on that of second laser beam. Therefore, dynamics of first laser beam affects that of other and hence cross-focusing of the two laser beams takes place. Numerical simulations have been carried out to investigate the effect of laser as well as plasma parameters on cross-focusing of laser beams and further its effect on power of excited EPW. It has been found that decentered parameters of the two laser beams have significant effect on power of EPW.
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Smyth, Noel F., and Bryan Tope. "Beam on beam control: Beyond the particle approximation." Journal of Nonlinear Optical Physics & Materials 25, no. 04 (December 2016): 1650046. http://dx.doi.org/10.1142/s0218863516500466.
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The all-optical control of the trajectory of a nonlinear optical beam propagating in a nematic liquid crystal cell is studied using a combination of modulation theory and full numerical solutions of the governing nematic equations. In detail, the output position of a signal beam is controlled via its interaction with a second, co-propagating control beam. The input positions of both the signal and control beams are fixed, with the output position of the signal beam determined by the input angle of the control beam. A simple modulation theory based on treating the optical beams as mechanical particles in a potential well is found to give only adequate agreement with numerical solutions. However, extending this modulation theory to include the detailed profiles of the beams, so that the beams are treated as rigid bodies moving in a potential well, leads to simple, extended equations which determine the input angle of the control beam required for a given output position of the signal beam. The predictions of this extended particle theory, or rigid body theory, are compared with full numerical solutions of the nematic equations and excellent agreement is found.
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Podobedov, B., and R. H. Siemann. "Coherent beam-beam interaction with four colliding beams." Physical Review E 52, no. 3 (September 1, 1995): 3066–73. http://dx.doi.org/10.1103/physreve.52.3066.
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Du, Chuang, Wen Ling Tian, Xiao Wei Wang, and De Jun Wang. "Experimental Research on Ceramsite Concrete Beams." Applied Mechanics and Materials 166-169 (May 2012): 708–11. http://dx.doi.org/10.4028/www.scientific.net/amm.166-169.708.
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Six specimens, including 4 ceramsite concrete beams(one of beams mixed into the polypropylene fiber ) and 2 normal concrete beams, were tested to investigate the flexural behavior. The test results show that cracking load of ceramsite concrete beams is slightly smaller than the ordinary concrete beam and cracking load of ceramsite concrete beams has significantly improved after mixing into the polypropylene fibers. The ultimate load of ceramsite concrete beams are no less than ordinary concrete beam,and fibers have not effects on the increase of ultimate load. Load-deflection curves were compared,and the results show that stiffness of ceramsite concrete beam is less than ordinary concrete beam. Ductility of ceramsite concrete beam is poorer than ordinary concrete beam. Fibers improve the stiffness of ceramsite concrete beam. Cover thickness of concrete beam has little effect on the performance of ceramsite concrete beam.
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Ahmed, Ausama, and Abdul Muttailb I. Said. "The Effect of Opening Size and Expansion Ratio on the Flexural Behavior of Hot Rolled Wide Flange Steel Beams with Expanded Web." Engineering, Technology & Applied Science Research 14, no. 1 (February 8, 2024): 13033–40. http://dx.doi.org/10.48084/etasr.6698.
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In some design cases, such as in castellated beams, cellular beams, or steel beams with expanded web, it is advantageous to strengthen and enhance the performance of steel beams by increasing the web depth. However, expanding the web of a steel beam is a unique engineering strategy. This modification not only enhances its ability to bear heavy loads but also reduces any bending or flexing while enabling longer distances between supports. The expanded steel beams can be achieved by making a horizontal cutting in the steel beam web and then adding an increment plate (with the same web thickness), called spacer plate, between the two halves of the web sections, thus improving stiffness and strength. To evaluate the behavior of such beams, nine specimens of HEA steel beams with expanded web ratios of 150%, 200%, and 250%, and one specimen as a reference beam, were fabricated. The specimens were evaluated under two-point load over a clear span length of 280 cm. From the experimental work it was found that for steel beams with expanded web that have 18 openings with 80 mm, the beams with an expansion ratio of 150% had the best performance according to load-deflection behavior with a reduction in load capacity by only 11%. Additionally, the beams with expansion ratios of 200% and 250% had no economic viability according to the analysis of load-deflection behavior with a reduction in load capacity by 49% and 62%, compared with the solid expanded steel beam with the same expansion ratio. For the second type of steel beam with expanding web with 9 openings of 160 mm width, the beams with expansion ratios of 200% and 250% were observed to perform better than the first type with a reduction in load capacity by 28% and 50%. Using larger opening width and a smaller opening number is considered the best option for beams with expansion web ratios of 200% and 250%, while on the contrary, using smaller opening width and higher numbers seems to be a better option for beams with 150% expansion web ratio. Expanding the depth of a steel beam provides design flexibility, reduces deflections, and allows for longer spans. These benefits enhance material efficiency and open up new architectural possibilities.
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Zhang, Tao, and Xian Lei Cao. "The Design Method Study of Double Reinforcement Beam Section." Key Engineering Materials 474-476 (April 2011): 2311–14. http://dx.doi.org/10.4028/www.scientific.net/kem.474-476.2311.
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To simplify the reinforcement design process of double reinforcement beam section, the concept and application of double reinforcement bean section were introduced, and the appropriate application conditions of reinforced beam in practical engineering and the structural design requirements of beams with double reinforcement section designing were analyzed. The results show that the design value of the negative moment, the beam section size and strength grade of concrete shall meet his requirements of the structural design, then the relational expression is derived, applying this formula to judge whether they meet the preliminary requirements before the calculation of beam reinforcement. Compared with the engineering example shows that the design equations is more simple and accurate, but is the upper limit, and the results can provide a reference for the engineering design and related research.
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Abdulsahib, Imad A., and Qasim A. Atiyah. "Vibration Analysis of a Symmetric Double-Beam with an Elastic Middle Layer at Arbitrary Boundary Conditions." Mathematical Modelling of Engineering Problems 9, no. 4 (August 31, 2022): 1136–42. http://dx.doi.org/10.18280/mmep.090433.
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Vibration of double beams with an elastic connected layer has been studied in this paper by assuming that the beam is a Bernoulli-Euler beam. The natural frequencies equations of the symmetric double beam have been computed at arbitrary boundary conditions. The behavior of those frequencies has been investigated with a change in the stiffness of connected layer, modulus of elasticity of beam, length of beam, mass density of beam, and thickness of beam. The high effect of the elastic connected layer on the higher natural frequencies of a cantilever double beam is less than that in the clamped and free double beams. The increase in the thickness of upper and lower beams made a high increase in the values of lower natural frequencies in all types of beams. The change in the modulus of elasticity values of double beam becomes high on the lower natural frequencies but without enlarging the influence on the higher frequencies, especially in the cantilever double beam. The similar effect of change in the mass density of the beam resulted in the same influence on the higher and lower natural frequencies in all types of beams. The length of the beam enlarges the influence on the higher natural frequencies of clamped and free.
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Raad Shaker, Hussein, Layth A. Al-Jaberi, and Wissam AlSaraj. "Flexural behavior of steel fiber reinforced slag- based geopolymer concrete beams." Nexo Revista Científica 36, no. 06 (December 31, 2023): 1049–61. http://dx.doi.org/10.5377/nexo.v36i06.17462.
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This study includes tested nine reinforced concrete beams. It’s designed to fail in flexural under two-point load. All beams are classified according to the type of concrete and the percentage of PVA into three groups. The first group including four reinforced geopolymer concrete beams with percent of PVA was 0.2 %; second group including four reinforced geopolymer concrete beams with percent of PVA was 0.75 % and third group including one reinforced normal concrete beam. The results showed when comparing the geopolymer concrete beam with the normal concrete beam, noticed that the ultimate strength is equivalent to many times the normal concrete. The best percentage for improving the ultimate load for beam NO.6 (GSSB10) where the percentage of increase was 132% this beam is reinforced by steel bars 2ɸ12mm at top and 2ɸ16mm at bottom. As for the other beams, the percentage increase in ultimate load was for beam NO.1 (46%), beam NO.2 (99%), beam NO.3 (13%), beam NO.4 (60%), beam NO.5 (58%), beam NO.7 (32%) and beam NO.8 (66%). The maximum deflection in all samples was high compared with the normal concrete, where the ultimate deflection reached 30 mm, while in the normal concrete it was 9.65 mm.
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Badawy, Amr H., Ahmed Hassan, Hala El-Kady, and L. M. Abd-El Hafez. "The Behavior of Reinforced and Pre-Stressed Concrete Beams under Elevated Temperature." International Journal of Engineering Research in Africa 47 (March 2020): 15–30. http://dx.doi.org/10.4028/www.scientific.net/jera.47.15.
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The behavior of unbounded post tension and reinforced concrete beams under elevated temperature was presented. The experimental work was consisted of two major phases. In the first phase, the objective was studying the mechanical performance of prestressed beam, prestressed beam with steel addition and reinforced concrete beams respectively were studied. In the second phase, the residual mechanical performance of prestressed beam, prestressed beam with steel addition and reinforced concrete beams under elevated 400oC, for 120 minutes durations. The failure mechanisms, ultimate load capacity, and deflection at critical sections were monitored. The numerical prediction of the flexural behavior of the tested specimens is presented in this paper. This includes a comparison between the numerical and experimental test results according to ANSYS models. The results indicate that the prestressed beam with steel addition and reinforced concrete beams had higher resistance to beams under elevated 400oC than that of prestressed concrete beam in terms of ultimate capacity. It is also shown that the reinforced concrete beams have higher resistance to beams under elevated temperature than that of prestressed beam, prestressed beam with steel addition.
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Hamid, N. A. A., N. Salleh, N. Ali, S. R. Abdullah, S. H. Adnan, and Z. Jamellodin. "Strengthening of Reinforced Concrete Beams with Circular Opening at Flexure Zone by Various Types of Fiber Reinforced Polymer." IOP Conference Series: Earth and Environmental Science 1022, no. 1 (May 1, 2022): 012053. http://dx.doi.org/10.1088/1755-1315/1022/1/012053.
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Abstract This paper aims to investigate the flexural behaviour of reinforced concrete (RC) beams containing circular opening at mid-beam span and strengthened using externally bonded Textile Reinforced Concrete (TRC) sheets, Carbon Fibre Reinforced Polymer (CFRP) sheets and Carbon Fibre Reinforced Polymer (CFRP) plates. The flexural behaviour including ultimate load, deflection, crack pattern as well as failure mode was investigated. Five RC beams with the dimensions of 1700 mm length and cross section of 200 mm x 250 mm with design concrete strength of 64 N/mm2 were tested under 4-points loading. The tested RC beams consists of solid beam as a control beam, unstrengthened RC beam with circular opening and strengthened RC beams with circular opening. The circular opening with ratio of 0.32 is classified as small opening with diameter of 80 mm was kept constant for all beam specimens. The inclusions of circular opening at the middle of beam span slightly decreased the ultimate load of beam about 6.2% compared to control beam. The reduction of stiffness was also experienced in RC beam with opening. The application of strengthening in beams with circular openings manages to regain the beam capacity about 17.5 to 22.6% higher than the unstrengthened RC beams with opening.
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Patkar, Aniket, and Santosh Mukkawar. "Break even analysis & response of longer span frames with or without post-tensioned beams in multipurpose hall." IOP Conference Series: Materials Science and Engineering 1197, no. 1 (November 1, 2021): 012011. http://dx.doi.org/10.1088/1757-899x/1197/1/012011.
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Abstract In this paper analyzed the RC a nd PT Beam against variation in the clear span length of the beam. This work includes the design and estimate of Cost/Beam from 5m span up to 15m span length of the beam. Also, The response of the frame following two variation in its modelling. Initially, The primary model consists of a conventional RCC frame with all beams and columns as RCC. The secondarily model considers peripheral beams as RCC and interior beams with PT. Such as ETABS software used to designed RC beam element and ADAPT-PTRC used to designed PT beam element. However it has been note that variation of cost with respect to the span of beam where the break-even point between RCC and PT technique is approx 7m Span. Also the control on deflection of beam by restrict the depth of beam by using unbonded Post-tensioned prestress concrete beam method. There is very good understand all aspects PT beam better than as compared with to RC beam in deflection against longer span length of beams. This paper gives suggestion about to reach a decidedly conclusion regarding which technique is superior over one another.
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Al Amli, Ali Sabah, Laith Shakir, Ali Abdulredha, and Nadhir Al-Ansari. "Behavior of Reinforced Concrete Beams with effect of Stiffened Plates." Civil Engineering Journal 5, no. 12 (December 3, 2019): 2569–78. http://dx.doi.org/10.28991/cej-2019-03091433.
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This study presents experimental work including an investigation conducted on five simply supported reinforced concrete beams under pure torsion. First beam without strengthening as a control beam. The other four beams were strengthened externally by bolted thin steel plates. For this test the load was applied gradually. The torque was increased gradually up to failure of the beam. The variables were the thickness and height of the steel plate that was externally connected to both sides of the rectangular reinforced concrete beam. The test results for the beams discussed are based on torque-twist behavior. The experimental results show that the attachment of thin steel plates by mechanical means to beams provides a considerable improvement in the torsional behavior of the reinforced concrete beams. Comparable to the reference beam, the maximum increase in the cracking and the ultimate torque of the composite beam was recorded for the reinforced concrete beam that strengthen by steel plate of (150) mm height, (2mm) thickness and (50mm) spacing between shear connectors (B1). The results revealed that the cracking torque, ultimate torque, global stiffness of beam and beam ductility for all composite beams increase with the increase of the plate's thickness, plate's height.
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Karvekar, Arvind Vishnu. "An Experimental Study on Rehabilitation of RC Beam by Stitching Method." International Journal for Research in Applied Science and Engineering Technology 9, no. 8 (August 31, 2021): 2955–60. http://dx.doi.org/10.22214/ijraset.2021.37891.
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Abstract: The current work presents an experimental study on rehabilitation of RC beam by stitching method. For the study, a total of Twenty-Four RC beams were casted and cured for 28 days. Among the beams casted, three is control beam. Under two point loading, the control beam was tested for ultimate failure load and remaining twenty one beams were loaded for 75% of the ultimate failure load. The damaged beams were then rehabilitated by Stitching method using two different patterns. The rehabilitated beams were tested for ultimate failure load and the results are compared with control beam and the effectiveness of the rehabilitation is determined. From the result it is observed that as the diameter is gone increasing the flexural strength of the beam is gone increasing. As the depth of insertion of the bar inside the beam is gone increasing the flexural strength of the beam is gone increasing. It is concluded from this study that stitching methods is effective to restore the flexure capacity of damaged beams. Keywords: Rehabilitation, Reinforced Concrete Beam, Stitching Method
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Declercq, Nico F. "Rayleigh angle incident ultrasonic beam shape design influence on reflected beam." Acta Acustica 7 (2023): 41. http://dx.doi.org/10.1051/aacus/2023037.
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Current evolutions in transducer design, such as phased arrays, but more importantly, metamaterials-based acoustic lenses, potentially enable generating specific beam shapes earlier unconsidered. It is known that the Schoch effect, when a bounded incident beam on a submerged solid reflects at the Rayleigh angle, depends on the beam width and the frequency. This work numerically explores the consequence of the shape of such beams on the Schoch effect and invites further experimental work. The study investigates square shapes and beams with exponential flanks compared to Gaussian reference profiles and incorporates diffraction upon sound propagation to resemble reality better. It is shown that stunning differences occur depending on the beam shape, particularly for square beams.
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Xu, Xin, Zheng Liu, Xue Han, and Chao Ge. "Experimental Research on the Stiffness of CFRP Reinforced Concrete Beam." Advanced Materials Research 744 (August 2013): 436–39. http://dx.doi.org/10.4028/www.scientific.net/amr.744.436.
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This thesis analyses the destruction mode, the crack developing and beam deflection changes of 20 reinforced concrete beams including un-strengthened beam, direct strengthened beam and secondary load reinforced beam through tests and researches. The results show that using CFRP to strengthen the reinforced concrete beams will not only effectively increase the bearing capacity of the beam, but also inhibit the beam cracking and improve the flexural rigidity of the beam during normal use. In addition, the initial damage will have a certain impact on the stiffness of the strengthened beam.
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Nong, Shengwei, Baojun Li, Lingcai Kong, Jian Huang, Xiaohuang Chen, Zhimei Jiang, Jun Yang, Yang Zou, and Zhongya Zhang. "Behavior of Existing Box Beams Repaired with High-Strength Mortar Layer and Ultra-High-Performance Concrete (UHPC) Overlay: Experimental, Numerical, and Theoretical Investigations." Buildings 14, no. 7 (July 5, 2024): 2052. http://dx.doi.org/10.3390/buildings14072052.
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Box beams constructed earlier were prone to inadequate bending capacity owing to low construction standards, overloading, and environmental degradation. To resolve the challenge, three full-scale box slab beams in service for 15 years were strengthened with a high-strength mortar layer and an ultra-high-performance concrete (UHPC) layer in this paper. The flexural performances of unstrengthened beams (control beam) and strengthened beams (mortar beam, UHPC beam) were investigated by in situ four-point bending tests and numerical simulations. The experimental results showed that the cracking of box beams, strengthened with high-strength mortar and UHPC layers, was effectively mitigated. In comparison to the control beam, the cracking load of the mortar beam and the UHPC beam increased by 20%, and the ultimate load increased by 23.5% and 35.3%, respectively. The high-strength mortar layer had little influence on the elastic-phase stiffness of box beams. In contrast, the stiffness of the elastic phase of the box beam, strengthened by the UHPC layer, increased by 32.9%. In the numerical simulations, the load-deflection curves obtained from finite elements and tests coincided well. The characteristic loads showed relatively good agreement with the test results, with errors below 10%. Combined with the tests and numerical analyses, the proposed equations for predicting the ultimate bearing capacities of the control beam, mortar beam, and UHPC beam were presented with a better prediction accuracy.
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R, Manimaran. "Composite Delta Beam for Slim Floor Construction." International Journal for Research in Applied Science and Engineering Technology 12, no. 3 (March 31, 2024): 382–88. http://dx.doi.org/10.22214/ijraset.2024.58811.
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Abstract: The structural behaviour of the composite Flush Beam for slim floor as a whole has been investigated. The deformation behaviour of the structural members Steel beams with trapezoidal cross-sections and specially punched webs were developed as composite beams in slim floors. The estimation of the flexural stiffness and bending capacity of composite slim beams is rather complicated, because the influence of many factors should be taken into account. These factors include variable section dimensions, Profile of the beam, stiffness of the beam and interaction between steel and concrete. In this paper, analytical investigations have been conducted to investigate the deflection behaviour of Flush beam specimens under monotonic loading. A design procedure is developed for composite slim floor Flush beams based on cross-sectional analysis and the flexural properties of the slim floor beams are evaluated. From the analytical investigation it was found that the deflection of delta beam is 48% less than the conventional I-beam More over the stiffness of the Delta beam is 49.8% higher than the I-beam
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Jia, Lian Guang, Ya Gao, and Li Zhe Hou. "Mechanical Properties of Reinforced Steel Beams Influenced by the Degree of Unloading." Advanced Materials Research 146-147 (October 2010): 1293–99. http://dx.doi.org/10.4028/www.scientific.net/amr.146-147.1293.
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Several I-shaped steel beams reinforced by CFRP are unloaded at different levels and the mechanical properties are analyzed and compared. Five forms of I-shaped steel beam (beam without reinforced; reinforced beam in condition of non-unloading; reinforced beam in condition of 50% unloaded; reinforced beam in condition of 75% unloaded; reinforced beam in condition of completely unloaded) are analyzed and compared. Conclusions are made that the stiffness and yielding load of I-shaped steel beams reinforced by CFRP are improved and the bearing capacity is improved for certain degree when the beams are unloaded.
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Kim, Jongwon. "Beam tests of a beam position monitor for ISOL operation." Journal of Instrumentation 18, no. 04 (April 1, 2023): T04004. http://dx.doi.org/10.1088/1748-0221/18/04/t04004.
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Abstract A beam position monitor (BPM) is built and tested to monitor the stability of high intensity proton beams accelerated by a 70 MeV cyclotron for ISOL operation in the aspects of beam position and current. The prototype BPM has four pick-up electrodes with a length of 19 cm and uses Libera Spark™ to process signals. It was firstly tested using a moving wire method to calibrate beam positions and further tested when installed in the beam line together with a beam profile monitor during beam commissioning of the cyclotron. The prototype system produced well-defined signals for two transverse directions with a resolution of 0.1 mm and for beam intensity up to 600 μA. A beam-stop signal can be issued by the readout program for the Spark when beam instabilities evaluated by the program reach certain limits set for each operation. The non-destructive BPM monitoring of high-current beams will be integrated into the safety PLC after a series of ISOL operation are carried out.
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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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Guo, Nan, Chao Yang, Ling Li, Guodong Li, and Yan Zhao. "Experimental Study on Flexural Performance of Regulated Reinforced Glulam Beam after Long-Term Loading." Sustainability 13, no. 10 (May 17, 2021): 5556. http://dx.doi.org/10.3390/su13105556.
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Due to wood creep characteristics, the failure mode, bearing capacity, stiffness, and deformation of its components are doomed to be impacted by long-term loading. This paper conducted a comparative test on creep beams, regulated beams, and short-term beams based on the former long-term loading research. The results demonstrated that the glulam beam experienced tensile failure of the beam-bottom, while the horizontal joint failure and the local compressive failure of the beam-end happened in the reinforced glulam beam and the prestressed glulam beam. The bearing capacity of the creep beams decreased compared with that of the short-term beams; the decline in the bearing capacity of the ordinary glulam beams, the reinforced glulam beams, and the prestressed glulam beams ranged from 3.2% to 9.8%, from 1.6% to 13.2%, and from 2.9% to 9.2%, respectively. However, the bearing capacity of the regulated beam with the deformation restored to the initial value of the load increased by 4.6–14.1%. The prestressed regulation changed the distribution of the stress on the beam and thus enhanced its bearing capacity. The findings of this work could be used as a frame of reference for similar components in engineering applications.
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Holmes, A. J. T., and R. McAdams. "Space charge compensation of positive ion beams used in magnetic fusion applications." Nuclear Fusion 62, no. 6 (April 5, 2022): 066017. http://dx.doi.org/10.1088/1741-4326/ac544c.
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Abstract A model is presented for space charge neutralisation of positive ion beams. The model is used for the particular case of the beams used for magnetic based fusion applications. The beams consist, after a gas neutraliser, of ions and atoms at different energies. Account is taken of the contribution of all beam components to ionization of the background gas. Consideration is also given to not only beam heating of the plasma generated by the beam, due to Coulomb collisions, but also to Coulomb heating by fast electrons produced in ionization by all beam particles and stripping of the neutral components. Two approximations are considered for the motion of the secondary ions out of the beam potential; a drift approximation and a freefall approximation. All the beam plasma parameters can be calculated. The model is applied to a typical extracted beam of deuterium ions of 120 kV, 60 A. It is found that these beams are very highly compensated and that beam plasma heating by the electrons produced is generally greater than that due to the beam ions.
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Ali Sabah AL-Amili. "The Effect of Steel Plate on the Deflection of Self Reinforced Concrete Beam with and Without Opening." Diyala Journal of Engineering Sciences 6, no. 1 (March 1, 2013): 36–49. http://dx.doi.org/10.24237/djes.2013.06104.
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In this work aims at studying the influence of steel plate on the deflection of self- compacted reinforced concrete beams was investigated experimentally in this study to know the flexural behavior of these beams. Eight simply supported reinforced concrete beam were tested under the action of two point loads .The deflections of the beams with and without plate are measured. The steel plates of thickness (3 mm) with dimensions ( 170 × 350 mm) were used. These plates were sticked on the concrete beams using epoxy. The steel plate inside the beam was sticked with and without epoxy (epoxy type EP), while the beams were taken with and without opening (10 mm diameter). The results show that the plate increased the capacity of the beam by increased the value of failure load. Hence, the beam with internal plate with epoxy increased the failure load by 34.2% than beam without plate , and 24.6% than beam with internal plate without epoxy , and 19.7% than beam with external plate with epoxy .
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LIM, TEIK-CHENG. "ANALYSIS OF AUXETIC BEAMS AS RESONANT FREQUENCY BIOSENSORS." Journal of Mechanics in Medicine and Biology 12, no. 05 (December 2012): 1240027. http://dx.doi.org/10.1142/s0219519412400271.
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The mechanics of beam vibration is of fundamental importance in understanding the shift of resonant frequency of microcantilever and nanocantilever sensors. Unlike the simpler Euler–Bernoulli beam theory, the Timoshenko beam theory takes into consideration rotational inertia and shear deformation. For the case of microcantilevers and nanocantilevers, the minute size, and hence low mass, means that the topmost deviation from the Euler–Bernoulli beam theory to be expected is shear deformation. This paper considers the extent of shear deformation for varying Poisson's ratio of the beam material, with special emphasis on solids with negative Poisson's ratio, which are also known as auxetic materials. Here, it is shown that the Timoshenko beam theory approaches the Euler–Bernoulli beam theory if the beams are of solid cross-sections and the beam material possess high auxeticity. However, the Timoshenko beam theory is significantly different from the Euler–Bernoulli beam theory for beams in the form of thin-walled tubes regardless of the beam material's Poisson's ratio. It is herein proposed that calculations on beam vibration can be greatly simplified for highly auxetic beams with solid cross-sections due to the small shear correction term in the Timoshenko beam deflection equation.
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Koo, Ja Eun, Shin Kim, Ock Bae Ko, Danbi Lee, Young Pill Chong, Yoon-Koo Kang, Jooryung Huh, and Cheolwon Suh. "BEAC or BEAM Chemotherapy Followed by Autologous Stem Cell Transplantation in Non-Hodgkin’s Lymphoma Patients: Comparative Analysis on Efficacy and Toxicity." Blood 106, no. 11 (November 16, 2005): 5291. http://dx.doi.org/10.1182/blood.v106.11.5291.5291.
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Abstract Background: Non-Hodgkin’s lymphoma (NHL) is the major indication of high dose chemotherapy (HDC) followed by autologous stem cell transplantation (ASCT). However, little is known on the comparative efficacy and toxicity of various HDC regimens. Aims: This study aimed to compare the efficacy and toxicity of BEAC and BEAM regimen. Methods: Between April 1994 and February 2005, 97 NHL patients were received HDC with BEAC (N=69) or BEAM (N=28) followed by ASCT at Asan Medical Center. We matched one patient received BEAM with two patients received BEAC who has same International Prognostic Index (IPI). Thus total 84 patients (56 in BEAC group and 28 in BEAM group) were analyzed. Results: Of 84 patients, 55 (65.5%) were male, 29 (34.5%) were female and median age was 40.5 (15–65) years. Baseline characteristics such as age, sex, disease status at ASCT, histology, stage at ASCT, IPI were not different between two groups. Time to neutrophil engraftment (WBC>0.5′109/mm3) was significantly longer in BEAC group (14.5days) than in BEAM group (11.0days, p=0.002). Total amount of RBC transfusion was more in BEAC group than in BEAM group (6.5 units vs. 3.7 units, p=0.037). Time to platelet engraftment (platelet>20′109/mm3) and total amount of platelet transfusion were different between two groups. Patients received BEAM had more frequent WHO grade ≥ 2 diarrhea than those received BEAC (46.4% vs. 19.6%, p=0.010). But, other clinically important toxicity such as mucositis, nausea/vomiting, bleeding were not different between two groups. In addition, neutropenic fever and documented infection were not different between two groups. Two year overall survival (OS) rate was 30% in BEAC group and 66% in BEAM group. Two year event free survival (EFS) rate was 34% in BEAC group and 61% in BEAM group. Both OS and EFS was significantly superior in BEAM group than in BEAC group (p=0.049, p=0.032, respectively). Summary/Conclusions: BEAM appears to be a superior HDC regimen in the aspect of OS and EFS than BEAC while regimen related toxicity is similar except more frequent diarrhea in BEAM.
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Olanitori, Lekan Makanju, and Damilola David Fregene. "Behavior of under and over-reinforced concrete slender beams at failure." Nigerian Journal of Technological Research 16, no. 3 (September 28, 2021): 16–22. http://dx.doi.org/10.4314/njtr.v16i3.3.
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The focus of this paper is to examine the behavior of under and over-reinforced concrete slender beams at failure. The total number of the beams were five, with the provision of the following percentage of tension reinforcements: 1.01% for beam 1 (B1), 1.51% for beam 2 (B2), 2.01% for beam 3 (B3), 2.62% for beam 4 (B4) and 3.01% for beam 5 (B5). The beams were loaded with point loads at the center, with shear span/depth ratio of 3.8. The actual ultimate load of the experimental beam B1 was 141% of the estimated ultimate, while for beams B2, B3, B4 and B5, the actual ultimate loads were between 68% and 87% of the estimated ultimate loads for the beams respectively. The reinforced concrete beams B1, B2 and B3 had the capacity to sustain large deformation under constant loads before their ultimate failure, hence will give warning about the impending failure. For beams B4 and B5, although failed at higher loads had limited rotation capacity, hence will not give warnings about the impending failure. Therefore, 2.01% tension reinforcement is recommended as the maximum to be provided, so that the beam section can behave as a ductile section.
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Rahman, M. A., M. Jahangir Alam, and M. Akhtaruzzaman. "Characteristics Analysis of High Energy External Radiotherapy Beams in Water." Malaysian Journal of Medical and Biological Research 5, no. 1 (June 30, 2018): 51–60. http://dx.doi.org/10.18034/mjmbr.v5i1.450.
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High energy external radiotherapy beam is being used widely for cancer treatment. Biological effect of radiation is concerned with the evaluation of energy absorbed in the tissue. The study of photon and electron beam characteristics is necessary before calibration machine. The aim of this study was to analysis characteristics of depth dose of different energy beams in water to enhance the quality of the radiotherapy treatment planning. Beam is attenuated by the medium and the transmitted beam with less intensity causes lesser absorbed dose as the depth increases. Relative attenuation on certain points on the beam axis and certain percentage of doses on different depths for 4-15 MV photon beams and 4-18 MeV electron beams have been investigated. Depth dose characteristics of the beams do not show identical attributes as interaction of the beams with matters is mainly governed by beam quality. Attenuation and penetration parameters show variation with dosimetric parameters like field size due to scattering and source to surface distance due to inverse square law but the major parameter in interaction is energy. Detailed analysis of the beam characteristics helps to select appropriate beam for radiotherapy treatment when variety of beam energies available and hence to increase accuracy in radiotherapy treatment.
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Funakoshi, Y., N. Iida, M. Kikuchi, T. Mori, T. Natsui, Y. Ohnishi, M. Satoh, Y. Seimiya, and T. Yoshimoto. "Beam injection and beam quality in injector LINAC and in beam transport lines at SuperKEKB." Journal of Instrumentation 19, no. 02 (February 1, 2024): T02003. http://dx.doi.org/10.1088/1748-0221/19/02/t02003.
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Abstract At SuperKEKB, the maximum beam currents and the luminosity could be limited by the beam injection in the near future. We estimated requirements to the beam injection to achieve the next target luminosity of 1 × 1035cm-2s-1. Two cases of β y * = 1 mm and 0.8 mm are considered. A simulation shows that we need to suppress the emittance growth of the injecting positron beam in the beam transport (BT) line down to its design value to meet the requirement with β y * = 1 mm. In the case of β y * = 0.8 mm, we need to improve dynamic aperture of LER in addition to the suppression of the emittance growth. Efforts to improve the beam quantity and quality in LINAC and in BT are summarized. The present most serious problem concerning quality of the injecting beams is emittance growth in the BT lines for both electron and positron beams. Simulations and experiments show that the effects of ISR and CSR in the BT lines cause a large horizontal emittance growth of the electron beam. Several measures to suppress the emittance growth are under considerations.
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Zhang, Xizhi, Shaohua Zhang, and Sixin Niu. "Experimental studies on seismic behavior of precast hybrid steel–concrete beam." Advances in Structural Engineering 22, no. 3 (August 28, 2018): 670–86. http://dx.doi.org/10.1177/1369433218796411.
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This study aims to investigate the seismic behavior of precast hybrid steel–concrete beams. Five full-scale beam specimens, including four precast hybrid steel–concrete beams and a conventional precast concrete beam, were tested under cyclic loading. Furthermore, a new connection form was proposed to facilitate the constructability of the steel-to-concrete connection. The main experimental parameters were the steel beam length and the longitudinal reinforcement ratio. In addition, the influence of the reduced beam section of the steel beam on seismic behavior of precast hybrid steel–concrete beams was observed and investigated. Detailed analysis was performed on the basis of the observed failure modes and the relationships obtained from the experimental data, such as hysteretic curves, deformation curves, stiffness degradation curves, energy dissipation capacity, load curvature curves, and strain development curves. Experimental results showed that the failure mode of precast hybrid steel–concrete beams was different from that of precast concrete beams. The precast hybrid steel–concrete beam retained ductility comparable to that of precast concrete beams. Generally, the initial stiffness of precast hybrid steel–concrete beams was smaller than that of precast concrete beams, but the stiffness degradation was more stable. On the basis of measured crack propagation and failure mode, deformation curves, and the development of strain in steel beams and longitudinal reinforcements, the stress between the steel beam and concrete beam can be effectively transmitted to one another by the proposed connection form.
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Chu, Dapeng, Yong Mao, Haoxiang Li, Hong Bie, and Yongjin Zhou. "Dual-Polarized Multi-Beam Fixed-Frequency Beam Scanning Leaky-Wave Antenna." Sensors 23, no. 11 (May 25, 2023): 5070. http://dx.doi.org/10.3390/s23115070.
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A fixed-frequency beam-scanning leaky-wave antenna (LWA) array with three switchable dual-polarized beams is proposed and experimentally demonstrated. The proposed LWA array consists of three groups of spoof surface plasmon polaritons (SPPs) LWAs with different modulation period lengths and a control circuit. Each group of SPPs LWAs can independently control the beam steering at a fixed frequency by loading varactor diodes. The proposed antenna can be configured in both multi-beam mode and single-beam mode, where the multi-beam mode with optional two or three dual-polarized beams. The beam width can be flexibly adjusted from narrow to wide by switching between multi-beam and single-beam states. The prototype of the proposed LWA array is fabricated and measured, and both simulation and experimental results show that the antenna can accomplish a fixed frequency beam scanning at an operating frequency of 3.3 to 3.8 GHz with a maximum scanning range of about 35° in multi-beam mode and about 55° in single-beam mode. It could be a promising candidate for application in the space–air–ground integrated network scenario in satellite communication and future 6G communication systems.
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Li, Shengyuan, Henglin Lv, Tianhua Huang, Zhigang Zhang, Jin Yao, and Xin Ni. "Degradation of Reinforced Concrete Beams Subjected to Sustained Loading and Multi-Environmental Factors." Buildings 12, no. 9 (September 5, 2022): 1382. http://dx.doi.org/10.3390/buildings12091382.
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In the process of service, reinforced concrete structures have to bear both load and multi-environmental factors. The deterioration of reinforced concrete beams is critical to the durability, safety, and sustainability of reinforced concrete structures. The main aim of the present research is to determine the degradation mechanism of reinforced concrete beams subjected to sustained loading and multi-environmental factors. Reinforced concrete beam specimens were prepared, loaded and then exerted multi-environmental factors. At the end of each degradation period, the degradation of concrete (chemical contents of concrete beam surfaces, carbonation depth, compressive strength and maximum cracks) and the corrosion of steel bars (corrosion ratio and tensile strength) were continuously measured. Moreover, degraded reinforced concrete beams were flexural loaded in four-point bending failure tests. The degradation mechanism of reinforced concrete beams subjected to sustained loading and multi-environmental factors was analyzed. Thus, this study can promote a comprehensive understanding of reinforced concrete beams subjected to sustained loading and multi-environmental factors.
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Adachi, Ahoro, Takahisa Kobayashi, Kenneth S. Gage, David A. Carter, Leslie M. Hartten, Wallace L. Clark, and Masato Fukuda. "Evaluation of Three-Beam and Four-Beam Profiler Wind Measurement Techniques Using a Five-Beam Wind Profiler and Collocated Meteorological Tower." Journal of Atmospheric and Oceanic Technology 22, no. 8 (August 1, 2005): 1167–80. http://dx.doi.org/10.1175/jtech1777.1.
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Abstract In this paper a five-beam wind profiler and a collocated meteorological tower are used to estimate the accuracy of four-beam and three-beam wind profiler techniques in measuring horizontal components of the wind. In the traditional three-beam technique, the horizontal components of wind are derived from two orthogonal oblique beams and the vertical beam. In the less used four-beam method, the horizontal winds are found from the radial velocities measured with two orthogonal sets of opposing coplanar beams. In this paper the observations derived from the two wind profiler techniques are compared with the tower measurements using data averaged over 30 min. Results show that, while the winds measured using both methods are in overall agreement with the tower measurements, some of the horizontal components of the three-beam-derived winds are clearly spurious when compared with the tower-measured winds or the winds derived from the four oblique beams. These outliers are partially responsible for a larger 30-min, three-beam standard deviation of the profiler/tower wind speed differences (2.2 m s−1), as opposed to that from the four-beam method (1.2 m s−1). It was also found that many of these outliers were associated with periods of transition between clear air and rain, suggesting that the three-beam technique is more sensitive to small-scale variability in the vertical Doppler velocity because of its reliance on the point measurement from the vertical beam, while the four-beam method is surprisingly robust. Even after the removal of the rain data, the standard deviation of the wind speed error from the three-beam method (1.5 m s−1) is still much larger than that from the four-beam method. Taken together, these results suggest that the spatial variability of the vertical airflow in nonrainy periods or hydrometeor fall velocities in rainy periods makes the vertical beam velocities significantly less representative over the area across the three beams, and decreases the precision of the three-beam method. It is concluded that profilers utilizing the four-beam wind profiler technique have better reliability than wind profilers that rely on the three-beam wind profiler technique.
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E, Linzhongyang, Zhijing Wu, Fengming Li, and Guangping Zou. "A Finite/Spectral Element Hybrid Method for Modeling and Band-Gap Characterization of Metamaterial Sandwich Plates." Materials 16, no. 3 (January 27, 2023): 1098. http://dx.doi.org/10.3390/ma16031098.
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In this study, elastic metamaterial sandwich plates with axially deformed Timoshenko beam cores, considering both the out-of-plane and in-plane deformations of the face plates, are designed and the vibration band-gap properties are explored. The beam cores act as local resonators that can bear axial force, bending moment and shearing force. The finite element method (FEM) and the spectral element method (SEM) are combined to create the finite/spectral element hybrid method (FE-SEHM) for establishing the dynamic model and calculating the frequency response functions (FRFs) of the elastic metamaterial sandwich plate with axially deformed beam cores. It is observed that the metamaterial sandwich plate possesses both the axial and transverse vibration band-gaps of the beams, and the two kinds of band-gaps are independent. Compared with the metamaterial sandwich plates with rod cores, those with axially deformed beam cores have more extensive application ranges for vibration reduction.
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Yang, E. Chuan, Xiang Zhao, and Ying Hui Li. "Free Vibration Analysis for Cracked FGM Beams by Means of a Continuous Beam Model." Shock and Vibration 2015 (2015): 1–13. http://dx.doi.org/10.1155/2015/197049.
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Based on Euler-Bernoulli beam theory and a continuous stiffness beam model, the free vibration of rectangular-section beams made of functionally graded materials (FGMs) containing open edge cracks is studied. Assuming the material gradients follow exponential distribution along beam thickness direction, the conversion relation between the vibration governing equations of a FGM beam and that of an isotropic homogenous beam is deduced. A continuous function is used to characterize the bending stiffness of an edge cracked FGM beam. Thus, the cracked FGM beam is treated as an intact beam with continuously varying bending stiffness along its longitudinal direction. The characteristic equations of beams with different boundary conditions are obtained by transfer matrix method. To verify the validity of the proposed method, natural frequencies for intact and cracked FGM beams are calculated and compared with those obtained by three-dimensional finite element method (3D FEM) and available data in the literature. After that, further discussions are carried out to analyze the influences of crack depth, crack location, material property, and slenderness ratio on the natural frequencies of the cracked FGM beams.
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Jayaramappa, N. "Experimental Studies on Reinforced Concrete and Ferrocement Beams." IRA-International Journal of Technology & Engineering (ISSN 2455-4480) 5, no. 3 (December 30, 2016): 77. http://dx.doi.org/10.21013/jte.v5.n3.p4.
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<div><p><em>Arch structures have been utilized through the ages, beginning in the ancient civilizations of Greece, Egypt and Rome, to present day with their common use in bridges. Arches are well known for the ability to carry loads spanning large areas. Also now a day’s Ferrocement is being used extensively for various applications where use of normal concrete is hard to fulfil the present day requirements. In this paper experimental studies are carried out to understand the flexural behaviour of Reinforced concrete beams of grade M20 with HYSD reinforcement and Ferrocement hollow beams of cement to sand ratio of 1:3 and water cement ratio of 0.4. A total of four beams were cast in which two are straight beams and another two are arched beams. In that two straight beam, one is reinforced concrete beam with minimum reinforcement and another one is Ferrocement hollow beam and in two arch beams, one is reinforced concrete beam and other is Ferrocement hollow beam. All beams are rectangular in cross-section of size 200 x 200 mm and the span length is 2500 mm. The arch beam is provided with a rise at centre of 0.8 m. The Ferrocement beam is made of mortar with hollow cross section using hexagonal wire mesh with thickness of 40 mm and all the specimens are cured for 28 days. Flexural tests are carried out on conventional RC beam and Ferrocement hollow beams for simply supported condition. The test results are presented in terms of load deflection behaviour, ultimate load, cracking load and crack pattern with respect to reinforced concrete beam and Ferrocement hollow beam.</em></p></div>
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Yasen, Zena, . Assim Lateef, and Ammar Khazaal. "Structural Behavior Of Simple Supported Two Layers Reinforced Concrete (Normal strength concrete & Mortar with 3-Dimension glass fiber), Beams." Tikrit Journal of Engineering Sciences 28, no. 2 (June 17, 2021): 93–106. http://dx.doi.org/10.25130/tjes.28.2.08.
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This paper represents an experimental investigation of the layered concrete beam. It contains studying the possibility of using the mortar intervention with layers of glass fibre at the tension zone in a loaded supported concrete beam. To produce a beam with less weight than the beam with all Normal concrete and detecting the effect of this replacement on beam properties. A rectangular beams section (150*200*1000)mm cast with NSC (normal strength concrete) at compression zone and mortar with layers of 3D glass fibre used as a part of the tension zone. The produced beams are layered beams with a lighter weight than the homogenous RC beam. Three deferent levels of the replaced layers (1/3,1/2, and 2/3 of the beam thickness) were studied, all beams were tested under Two point load till failure. The maximum load capacity result shows an apparent lowering in the load capacity of the beam, but as the lightweight layer increases, this lowering in the load capacity becomes less. for (1/3,1/2 and 2/3) of the beam thickness replace with mortar and 3D textile fibre, the lowering percentage of failure load compare with the homogenous reinforced concrete beam are (33.04%, 27.18%, and 19.73%), and the lowering in weight is (5.45%%, 9.07%, and 12..92%) for the same sequence, respectively. Stiffness, ductility and toughness of all beams are tested. An apparent lowering in the stiffness value of the layered beams is recorded with the reference ones. At the same time, it shows an increase in the toughness and toughness value
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Wi, Daehan, and Angela A. Sodemann. "Exploring User Perception Challenges in Vibrotactile Haptic Display Using Resonant Microbeams under Contact with Skin." Multimodal Technologies and Interaction 3, no. 2 (May 28, 2019): 38. http://dx.doi.org/10.3390/mti3020038.
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Resonant vibrotactile microbeams use the concept of resonance to excite the vibration of cantilever beams, which correspond to pixels of an image. The primary benefit of this type of tactile display is its potential for high resolution. This paper presents the concept of the proposed system and human skin contact experiments to explore user perception challenges related to beam vibration during skin contact. The human skin contact experiments can be described in five phases: dried skin contact to metal beam tips, wet and soaped skin contact to metal beam tips, skin contact with a constraint, normal force measurement, and skin contact to the tips of silicone rubber beams attached to metal beam tips. Experimental results are analyzed to determine in what cases of skin contact the beams stop vibrating. It is found that the addition of silicone rubber beams allows the primary metal beams to continue vibrating while in contact with skin. Thus, the vibration response of a metal beam with silicone rubber beams is investigated for the better understanding of the effect of silicone rubber beams on the metal beam vibration.
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Li, Gui Bing, Yu Gang Guo, and Xiao Yan Sun. "Investigation on Flexural Performance of RC Beams Flexurally Strengthened by Soffit-Bonding and Side-Bonding CFRP Sheets." Advanced Materials Research 284-286 (July 2011): 2521–25. http://dx.doi.org/10.4028/www.scientific.net/amr.284-286.2521.
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It is an effective way to increase the flexural performance of reinforced concrete (RC) beam by externally bonding fiber reinforcement polymer (FRP) laminate on the soffit of the beam. However, there is little investigation on flexural behavior of RC beam by side-bonding FRP laminates. To investigate the difference of flexural behavior between soffit-bonding and side-binding FRP laminates RC beams, a total of 9 RC beams were tested, including 8 strengthened beams and 1 control beam. The test results showed that: the first crack load of RC beam strengthened by side-bonding CFRP laminates is much bigger than that of RC beam strengthened by soffit-bonding CFRP laminates.The first crack load of side-bonding CFRP laminates beams improved significantly;side-bonding and soffit-bonding methods have the same effect on the flexural stiffness of RC beams with same quantity of CFRP laminates before tension steel rebar yielding. However, side-bonding can remarkably decrease the crack width and change the crack pattern.Side-bonding of CFRP laminates can extend the pre-crack stage of the strengthened beam;the first yielding load and the ultimate load of beams cannot be improved significantly by side-bonding FRP laminates.
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Urquhart, J. S., M. G. Hoare, C. R. Purcell, K. J. Brooks, M. A. Voronkov, B. T. Indermuehle, M. G. Burton, N. F. H. Tothill, and P. G. Edwards. "Characterisation of the Mopra Radio Telescope at 16–50 GHz." Publications of the Astronomical Society of Australia 27, no. 3 (2010): 321–30. http://dx.doi.org/10.1071/as10002.
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AbstractWe present the results of a programme of scanning and mapping observations of astronomical masers and Jupiter designed to characterise the performance of the Mopra Radio Telescope at frequencies between 16 and 50 GHz using the 12-mm and 7-mm receivers. We use these observations to determine the telescope beam size, beam shape, and overall telescope beam efficiency as a function of frequency. We find that the beam size is well fit by λ/D over the frequency range with a correlation coefficient of ∼90%. We determine the telescope main beam efficiencies are between ∼48 and 64% for the 12-mm receiver and reasonably flat at ∼50% for the 7-mm receiver. Beam maps of strong H2O (22 GHz) and SiO masers (43 GHz) provide a means to examine the radial beam pattern of the telescope. At both frequencies, the radial beam pattern reveals the presence of three components: a central ‘core’, which is well fit by a Gaussian and constitutes the telescopes main beam; and inner and outer error beams. At both frequencies, the inner and outer error beams extend out to ∼2 and ∼3.4 times the full-width half maximum of the main beam, respectively. Sources with angular sizes of a factor of two or more larger than the telescope main beam will couple to the main and error beams, and therefore the power contributed by the error beams needs to be considered. From measurements of the radial beam power pattern we estimate the amount of power contained in the inner and outer error beams is of order one-fifth at 22 GHz, rising slightly to one-third at 43 GHz.
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Yusupov, A. K., H. M. Muselemov, and T. O. Ustarhanov. "Metal-wood crane beam calculation." Herald of Dagestan State Technical University. Technical Sciences 47, no. 3 (October 1, 2020): 122–31. http://dx.doi.org/10.21822/2073-6185-2020-47-3-122-131.
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Objective. The development of structures and calculation of metal-wood crane beams are associated with specific difficulties. The article discusses the methods of calculation and design of metal-wood crane beams. In this case, an algorithm is described that allows designing systems that are rational in terms of material consumption. Methods. As an example, a metal-wood beam with a span of 12 m is used, which is supported by overhead cranes with a load capacity of 30 tf. The operation of a metal-wood crane beam was compared with a glue laminate crane beam without reinforcement. The reinforcement elements are "discarded" and replaced with elasto-yielding supports to calculate a glue laminate beam reinforced with metal elements (or a metal-wood beam). The flexibility of these supports is taken into account using the elastic support ratio r, which is determined depending on the stiffness of the supports, and the force in the metal elements is derived from the nodes balance. Result. In both variants of loading metal-wood crane beams, it was shown that the greatest bending moment occurred when the bridge wheel was located above the elastic support. Conclusion. It is rational to use a metal-wood crane beam when operating bridge cranes with a lifting capacity of up to 30 tf; metal-wood crane beams are recommended to be designed with spans up to 12 m; the comparison of glue laminate crane beams with metal-wood beams showed that metal-wood beams were 40-55% more efficient.
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Branesh Robert, J., R. Angeline Prabhavathy, P. S. Joanna, S. Christopher Ezhil Singh, Sivaraj Murugan, S. Rajkumar, and Shubham Sharma. "Flexural Behaviour of RC Beams with a Circular Opening at the Flexural Zone and Shear Zone Strengthened Using Steel Plates." Advances in Civil Engineering 2021 (December 2, 2021): 1–12. http://dx.doi.org/10.1155/2021/6733402.
Full textAbstract:
In this paper, an investigation on the behaviour of RC beams with circular openings in the flexural zone and shear zone strengthened using steel plates is presented. Totally seven beams were cast: a control beam, one beam with a circular opening of size of one-third the depth of the beam (100 mmϕ) in the flexural zone, one beam with opening strengthened using the steel plate, one beam with a circular opening of size of 100 mmϕ in the shear zone, one beam with an opening in the shear zone strengthened using the steel plate, one beam with two circular openings of size of 100 mmϕ in the shear zone, and another beam with two openings in the shear zone strengthened using the steel plate. The experiments were conducted in a loading frame of 400 kN capacity. The beams were subjected to two-point loading. The ultimate load carrying capacity reduced marginally by 1.78% and 2.8% compared to that of the control beam when a circular opening of 100 mmϕ was provided in the flexural zone and shear zone, respectively, and when the opening was strengthened with steel plates, it reduced by 3.04% and 25%, respectively, but the ductility increased when steel plates were provided. Beams with an opening of size of one-third the depth of the beam (100 mmϕ) in the flexural zone strengthened with the steel plate can be provided, as the load carrying capacity is only marginally reduced compared to the control beam, and the ductility is more when compared with beams with unstrengthened openings.