Traditional Beam Research Articles

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Laguerre-Gaussian (LG) beams experience phase twist after long-distance transmission, making the orbital angular momentum (OAM) indistinguishable. This phenomenon becomes more severe in water due to the higher refractive index. Based on the physical principles of LG beams, this paper derives the mathematical expression for LG beam transmission in water to address this issue. It organizes and analyses the physical significance of each term. The exponential term responsible for phase twist is separated and phase compensation is applied to the initial LG beam. Simulation results show that after transmission through water, traditional LG beams exhibit a clockwise twisted distribution of isophase lines. By applying the phase compensation method proposed in this paper, the phase of the initial LG beam is modulated and when the LG beam reaches the observation plane, the isophase lines become straight, verifying the effectiveness of the method. This compensation method holds significant value for LG beams in advanced physics research.

Energy harvesting of a metamaterial beam with acoustic black holes

Abstract This paper proposed an improved metamaterial piezoelectric beam with the acoustic black holes (ABHs) for low-frequency energy harvesting. The ABHs are embedded in the local resonant beams distributed on both sides of the primary beam. Piezoelectric plates are attached to the ABHs, leveraging the energy-focusing effect to enhance the energy harvesting performance. Finite element simulation results indicate that the energy harvesting electrical energy has improved by 6.92 times compared to the traditional metamaterial resonant beam without ABHs. Parameter analysis indicates that increasing the number of local resonators and extending the length of the piezoelectric patches can further enhance energy harvesting performance. However, reducing the truncation thickness of the ABH boosts energy harvesting but compromises structural strength. Extending the ABH length and increasing load resistance within the appropriate range are conducive to energy harvesting. Besides, the optimal load resistance varies with frequency. These findings provide useful guidance for future applications of improved metamaterial beam.

Study on static performance of the steel-concrete joint in a high-speed railway hybrid girder low tower cable-stayed bridge

The steel-concrete joint (SCJ) of mixed beam bridge plays a key role in connecting concrete box girder and steel box girder, but its complex structure makes its mechanical properties unclear. Compared with traditional mixed beam cable-stayed Bridges, mixed beam low tower cable-stayed Bridges show stronger competitiveness. However, there is still a lack of published literature on the study of SCJ of mixed beam low tower cable-stayed Bridges for high-speed railway. In order to study its mechanical properties, a scale model test with similar ratio of 1:5 was carried out under the background of Yongjiang River mega-bridge. The results show that under the action of 5.0 times maximum axial force and maximum negative bending moment, the components of the test model are still in the elastic state, the vertical deformation of the model is continuous and smooth, and the slip between steel and concrete is small, which indicates that the model has good bearing capacity and safety. At the same time, the force transfer mechanism of steel-hybrid section under axial compression is discussed by finite element analysis(FEA). The numerical results show that the rear bearing plate is the main force transfer member of the SCJ, while the front bearing plate transmits a small proportion of axial force. Improving the strength of concrete has limited effect on the transmission path, but can enhance the overall stiffness. The increase of the thickness of the rear pressure plate and the T-rib with variable section mainly affects the force transfer ratio of the rear bearing plate, but has little effect on other force transfer indexes and the overall stiffness. The increase of the stiffness of the shear connectors significantly affects the force transfer proportion and the force transfer uniformity of the bearing plate, but its increase is far more than the change of the force transfer index, and the influence on the overall stiffness of the joint section can be ignored. The results can provide reference for the subsequent research and design of similar structures.

Numerical Simulation of GFRP-reinforced Rectangular Concrete Beams and Proposed Design Expressions

Rebar corrosion, which has emerged as a primary detrimental factor, significantly impacts the structural performance, durability, and overall serviceability of reinforced concrete (RC) structures. In response to this issue, the growing use of GFRP, which offers superior corrosion resistance compared to steel, highlights the need to compare its performance with traditional steel-reinforced beams. To address this need, this study aims to evaluate the flexural behavior of beams reinforced solely with GFRP rebar and assess their structural performance relative to steel-reinforced beams. To achieve this, finite element models of both steel-reinforced and GFRP-reinforced beams were developed using ANSYS software. The analysis focused on load-bearing capacities, displacement characteristics, and crack patterns, and included the calculation of strain energies corresponding to collapse prevention performance limits. Overall, the study concludes that these modifications enhance design guidelines for GFRP-reinforced beams, offering improved practical applications in structural design. Significant findings include the proposed modification to the minimum reinforcement ratio equation in ACI 440.1R-15 for GFRP-reinforced concrete, the introduction of a suggested strain reduction factor for GFRP rebar, and the revision of the effective moment of inertia equation with coefficients of 0.05 and 0.95. These revisions improved the general performance indicator to 1.17, yielding better results compared to other equations in the literature. The study concludes that these modifications enhance design guidelines for GFRP-reinforced beams, offering improved practical applications in structural design.

High energy circular Pearcey beams generation using phase-only metasurfaces with complex function fitting method

In this paper, we use electromagnetic metasurfaces for the first time to generate the circular Pearcey beam. A complex function fitting method is proposed for generating the circular Pearcey beam, which can improve electric field intensity at focusing location, resulting in a high energy circular Pearcey beam with an increase of 31.77% compared to the traditional Pearcey beam design. A slowly varying envelope is applied to describe the amplitude of the Pearcey function. Meanwhile, considering the oscillation property of the Pearcey function, an additional phase is added to its original phase. Furthermore, the double-phase hologram (DPH) method is developed to realize phase-only metasurface design. Four full wave electromagnetic simulations are finished, which prove the effectiveness of our proposed Pearcey function fitting method and phase-only metasurface design. Two 10 GHz transmissive metasurfaces were designed, fabricated, and experimented to further validate our design. This circular Pearcey beam design is useful in near field wireless communication, microwave wireless power transmission, and simultaneous wireless information and power transfer.

Mechanical behaviour of rigid-flexible combined structures: Aluminium-inflated membrane beams for application in floating photovoltaic platform

This study aims to investigate the bending and failure behaviour of aluminium-inflated membrane beams for their applications in floating photovoltaic platforms. Four-point bending tests are conducted for a range of inflated pressures and two different deck heights to assess their effect on structural stiffness and ultimate bearing capacity. Meanwhile, the surface-based fluid cavity method is employed to develop the finite element model with the material properties determined by independent coupon-level tests. The bearing capacity of the aluminium-inflated membrane beam is positively correlated with the internal pressure and deck height. The midspan strain distribution is similar to those of the traditional four-point bending beam with the upper part undergoing compression and the lower part experiencing tension, however, the structural behaviour at the failure stage is different. Failure typically occurs due to localised depressions at the loading points on the aluminium deck, ultimately leading to structural failure. The numerical model closely matches the experimental data for the initial inflated and bending configurations, exhibiting a deviation of only 0.10 % to 0.46 % in diameter and 0.32 % to 5.57 % in equivalent bending stiffness. A parametric study shows that the loading properties of the beam are more sensitive to the internal pressure than the deck height and thickness.

Assessing the Fire Properties of Various Surface Treatments on Timber Components in Ancient Chinese Buildings: A Case Study from the Xianqing Temple in Changzhi, Shanxi, China

Traditional and modern coatings play a key role in enhancing the fire resistance of ancient Chinese buildings. However, further comparative analysis is needed on the fire properties of the two coatings and their effects on different timber structural components. This study focuses on the main hall of the Shanxi Changzhi Xianqing Temple, a typical traditional column and beam construction built between the Song and Jin periods. Firstly, the combustion characteristics of various timber structural component samples with different surface treatments (traditional “Yi-ma-wu-hui” and modern flame retardants) were analyzed using cone calorimeter. Secondly, the fire development process of the Xianqing Temple building model was analyzed by a fire dynamics simulator (FDS), and the effect mechanism of different surface treatments on the burning process was further studied. The results show that the fire resistance of timber structural components is significantly improved after modern and traditional surface treatments. The traditional method is more effective in delaying the peak heat release rate and reducing the surface temperature during combustion, while the modern surface treatment significantly prolongs the ignition time of the timber structural components. The FDS results confirm that modern and traditional surface treatments significantly improve the fire resistance of the building, delaying the flashover time by about 300 s, with no collapse occurring within 800 s. In addition, the fire resistance of buildings after traditional surface treatment is better compared to traditional methods. The above research results can provide direct data support for the selection and optimization of fireproof coatings and treatment methods for ancient buildings.

Development of a novel crack-resistance technique for concrete slab in the hogging moment region of continuous composite beam

Composite steel-concrete beams offer distinct mechanical advantages. However, concrete cracking in the hogging moment region limits the composite performance of the material. This study presents an innovative technique for enhancing the crack resistance of continuous steel-concrete composite beams, which involves the prestressing of the concrete slab in the hogging moment region through post-tensioning. Following the completion of the concrete slab in the sagging moment region, the prestress is released, thereby preserving pre-compression stress in the hogging moment region without the need for long-term prestressing. This technique is enhanced using uplift-restricted and slip-free connectors, which improve the efficiency of pre-stress introduction. Experimental tests were conducted on composite beams employing this novel technique, alongside numerical simulations. The results indicated that the proposed technique significantly mitigated concrete cracking in the hogging moment region. Specifically, the cracking load of the specimen using the new technique increased by 467 % compared to the traditional composite beam specimen, accompanied by a substantial reduction in both the quantity and width of cracks. Other primary mechanical performance indicators remained relatively similar; however, the new technique exhibited a 14 % increase in the ductility coefficient compared with the traditional method. Additionally, this technique influenced interface slip, moment redistribution, and strain response along the cross-section in both the hogging and sagging moment regions. The numerical results aligned closely with the experimental data, confirming their accuracy and effectiveness. The simulations provided solutions for various construction stages by incorporating different connection constitutive models with adequate precision. A parametric analysis was conducted, revealing a design method for the innovative technique.

Introduction of a modified anomalous vortex beam with self-focusing properties.

This study introduces and experimentally demonstrates the concept of a modified anomalous vortex beam (MAVB), which carries orbital angular momentum (OAM) and exhibits unique self-focusing properties. By utilizing holographic techniques and customizing phase masks, we precisely control the beam's phase and intensity distribution, enhancing self-focusing behavior while preserving traditional anomalous vortex beam features. We derive an analytical formula to describe MAVB propagation within a paraxial ABCD optical system. The self-focusing characteristics are influenced by initial parameters such as beam order, quantum number, beam waist, wavelength, and the modification parameter. Additionally, we simulate MAVB propagation and their OAM spectrum in maritime atmospheric turbulence. Through comprehensive theoretical analysis and experimental validation, we show how MAVBs achieve controlled self-focusing, leading to enhanced beam control and stability. Our study explores the mechanisms, design principles, and practical implications of MAVBs, emphasizing their potential to revolutionize optical applications.

Analysis of reinforcement effect of different anchoring forces on slope stabilised by prefabricated anchorage cable frame beams

Prefabricated anchorage cable frame beams represent a new approach to slope reinforcement, displaying distinct deformation and stress patterns under varying anchoring forces compared to traditional cast-in-place frame beams. This renders the traditional theories and engineering practices of cast-in-place beams inapplicable. Field tests and sophisticated finite-difference simulation models were established to examine the mechanical performance of prefabricated beams under different anchoring forces. Initially, field test results validated the simulation models against measured and theoretical data. Subsequently, the impact of different anchoring forces on slope deformation, structural deformation, and stress in frame beams were explored. The beam pressure at the anchoring point of prefabricated beams was 24 % lower than that of cast-in-place beams, exhibiting a linear relationship with increasing anchoring forces and heightened initial sensitivity. Prefabricated beams showed a 20–30 % reduction in anchoring force loss over traditional beams when the anchoring force is not greater than 40 t. Notably, tensile stress emerges in prestressed prefabricated beams when anchoring forces exceed 50 t. The slope deformation with the increasing of anchoring force can be described by a power function. A new deflection deformation index for frame beams was proposed, showing a 70 % reduction compared to cast-in-place beams. During sliding face degradation, deformation differences between adjacent prefabricated beams weaken the reinforcement effect compared to continuous cast-in-place beams. However, applying sufficient anchoring forces significantly mitigates this effect. A well-calibrated anchoring force ensures superior performance of prefabricated anchorage cable frame beams, with enhanced crack resistance, reduced anchoring force loss, minimal deflection deformation. Moreover, the prefabricated beam structure is easy for local replacement and maintenance. This study can make a reference for the application and design of prefabricated structures for slope stabilisation.

Study on Mechanical Properties of Steel-Strengthened Bamboo Beams with Webbing Opening

Bamboo beams are often reinforced with built-in steel sections to enhance their strength and load-bearing capacity. In this paper, we studied the effect of different parameters, including the location of the hole, the hole size, and the thicknesses of the steel and bamboo, on the mechanical properties of reinforced beams. The damage patterns, deformation characteristics, and force-transfer mechanisms, as well as the mechanical properties of reinforced beams with different hole shapes, underwent non-linear finite element analysis. The damage sustained by the reinforced bamboo beam differed from that of the traditional bamboo beam; two diagonal points formed a plastic hinge, mainly during the process of shear damage to the hole. It was determined that the hole size and the thickness of the bamboo have the greatest influence on the mechanical properties of the reinforced beam. The damage characteristics of the composited beams with different holes are similar; the bearing capacity of reinforced beams with open square holes is reduced by 10%–25%compared with circular holes.

Spinal chordoma and chondrosarcoma treatment experiences - a 20-year retrospective study from databases of two medical centers

The research retrospectively analyzed cases of spinal chordoma and chondrosarcoma involving patients who received treatment at the two hospitals between 2001 and 2023. Among the 48 patients studied (39 chordoma and 9 chondrosarcoma cases), the average age was 53.9 ± 15.8 years, with a range of 17 to 86 years. Out of these patients, 43 underwent excision surgery and were categorized based on tumor margin into negative (R0) or microscopically positive (R1) margin (n = 14) and macroscopically positive (R2) margin (n = 29) groups. The mean overall survival (OS) for R0/R1 and R2 groups was 156.5 ± 19.3 and 79.2 ± 11.9 months, respectively (p value = 0.012). The mean progression-free survival (PFS) for R0/R1 and R2 was 112.9 ± 24.4 and 25.5 ± 5.5 months (p value < 0.001). The study showed that regardless of whether patients in the R0/R1 or R2 groups received radiation therapy (RT) or not, there was no significant improvement in OS or PFS. Specifically, the OS and PFS for the RT only group were 75.9 ± 16.6 and 73.3 ± 18.0 months. In conclusion, the recommended treatment approach for spinal chordoma and chondrosarcoma remains en bloc resection surgery with an appropriate margin. Patients who are unsuitable for or decline surgery may find a beneficial disease control rate with traditional external beam photon/proton therapy.

A multifunctional scannable mounting device for computer guided implant surgery: An in vitro study

As part of the growing digitization of the dental field, clinicians are looking for ways to simplify digital workflow, reduce chairside time, and provide new work patterns for future applications. Whether scanning with a multifunctional apparatus (MFA) scan body results in improved scanning is unclear. The purpose of this in vitro study was to compare the horizontal, vertical, and angular deviations with the MFA scan body with a commercially available scan body (SBIO). Sixteen identically printed edentulous maxillary models were used to plan two Ø3.8×11.5-mm implants in the right maxillary first molar and left maxillary central incisor locations. Two implants in each model were installed using a surgical guide. The models were scanned using an intraoral scanner with MFA and then rescanned twice, with SBIO using the intraoral scanner and a laboratory 3D scanner. The implants were digitally positioned according to the scanned MFA and SBIO locations in standard tessellation language (STL) files. These STL files were superimposed on the reference laboratory 3D scanner STL files. Linear measurements included implant apex/cervical horizontal/vertical deviations, as well as implant axis angular deviations. Normality was evaluated with the Shapiro-Wilk test. Paired samples t tests (2 sided) were used for the mean SBIO-MFA deviation difference. To compare the molar/incisor sites, paired samples Wilcoxon tests were used (α=.05 for all tests). No statistically significant differences were found between the MFA/ SBIO deviations, for each of the 10 sites × deviation combinations (P>.05). Overall, the lowest endpoint of the 95% confidence intervals among the 8 linear measurement comparisons was -0.107 mm (coronal vertical deviation, right maxillary first molar site) and -0.30 degrees between the 2 angular measurement comparisons. The current in vitro study demonstrated high accuracy for the novel MFA device, similar to that of the standard SBIO scan body. Furthermore, the current study offers an alternative technique to evaluate the accuracy of implant placement by using scanning and back programming over the traditional postplacement cone beam computed tomography (CBCT) scanning.

A fast search method of buckling load for telescopic boom structure

The telescopic boom structures are extensively utilized in engineering applications involving large mobile cranes, aerial work platforms of significant height, and similar mechanical devices. These are predominantly fabricated using solid-webbed box types, latticed truss designs, or a combination thereof. Under load, they exhibit pronounced geometric nonlinear effects, with the relationship between load and displacement demonstrating marked nonlinear characteristics. This paper focuses on the geometric nonlinear modeling of slender multi flexible beam structures. The overall structural system is divided into several substructures, and the concept of multi flexible system modeling is borrowed to establish a follow-up connected body foundation on each substructure. By decomposing the node displacement and rotation in the substructure, the large displacement and large rotation of the node are decomposed into rigid body motion of the connected base and small displacement and small rotation relative to the connected base, effectively representing the large displacement and large rotation of the substructure as rigid body motion of the connected base. A modeling method for the geometric nonlinear analysis of slender and flexible multibody beam structures is proposed. By decomposing the nodal displacement and rotation within the substructures, the large displacement and rotation of the nodes are broken down into the rigid body motion of the body-fixed coordinate and small displacement and rotation relative to the body-fixed coordinate. This approach establishes the application conditions for calculating the structure’s virtual power of deformation using traditional beam elements with linear strain. A method for solving the instability load of slender and flexible multibody structures is proposed. This method integrates the characteristics of the system’s nonlinear equilibrium equations with respect to load, by deriving the system equations with respect to a load increment control parameter. This paper converts nonlinear equilibrium equations into first-order ordinary differential equation (ODE). The method proposed in this paper provides a more efficient solution for the buckling load of the telescopic boom. It can be used to systematically and quickly calculate the structure of the telescopic boom.

Advanced Beam Estimation for Antennas Via Patterned Coupling-Line Detection Board in Ka-Band

In this research, we present an innovative method for estimating the beams of array antennas. Traditional beam analysis methods rely on placing receiving antennas in the far-field region, which requires moving or rotating the Tx or Rx, and using radiation pattern measurements. However, such methods often demand vast spatial requirements and the use of high-cost network analyzers. In contrast, the technique proposed in this study utilizes a board patterned with coupling lines strategically placed in the antenna's near-field zone. Signals intercepted by these coupling lines undergo conversion into DC voltage via a power detector situated at the line terminus. Interestingly, this method enables beam estimation solely based on the DC voltage level output of the power detector, thus offering a cost-effective and space-efficient solution that represents a significant advancement from traditional beam estimation methods.

Experimental and Numerical Study on the Performance of Steel–Coarse Aggregate Reactive Powder Concrete Composite Beams with Uplift-Restricted and Slip-Permitted Connectors under Negative Bending Moment

An innovative form of steel–concrete composite beam, the steel–coarse aggregate reactive powder concrete (CA-RPC) composite beam with uplift-restricted and slip-permitted (URSP) connectors, is introduced in this paper. The aim is to enhance the cracking resistance under negative bending moments, which is a difficult problem for traditional composite beams, and to make the cost lower than using ordinary reactive powder concrete (RPC). An experimental investigation of the behavior of six specimens of simply supported steel–CA-RPC composite beams with URSP connectors under negative bending moments is presented in this paper. The test results validated that the cracking load of steel–CA-RPC composite beams could be approximately three times that of the ordinary steel–concrete composite beams while the bearing capacity and stiffness are almost the same. A numerical model, using the concrete damaged plasticity (CDP) model to simulate the behavior of the CA-RPC material, was proposed and successfully calculated the overall load–displacement relationship of the composite beams with sufficient accuracy compared with the experimental results, and the distribution of cracks and the failure mode of the beams could also be captured by this model. Furthermore, a parametric analysis was carried out to find out how the application of prestress, CA-RPC, and URSP connectors could affect the cracking resistance of the composite beams, and the results indicated that using CA-RPC and prestress made the main contributions and that the usage of URSP could boost the effect of the other two factors. The plastic resistance moment of the beams was also compared with the calculation results using the methods introduced in Eurocode 4, and it was proved that the calculation results were lower than the experimental results by approximately 10%, which meant that the method was reliable for this kind of composite beam.

Efficient distributed architecture and optimized subarray control strategy to facilitate large-scale coherent beam combination.

Traditional coherent beam combination (CBC) system architecture has revealed inadequacies in meeting the concurrent demands of large-scale deployment and high-bandwidth requirements. Addressing this challenge, we propose a distributed CBC system architecture based on the optimized stochastic parallel gradient descent (SPGD) algorithm. Our strategy segments the large-scale laser array into multiple independent smaller-scale subarrays, ensuring their efficient phase convergence through the introduction of corresponding reference lasers while avoiding interference when integrating different subarrays. Moreover, the piecewise SPGD algorithm is proposed and the intensity of the reference laser is modulated to further improve the convergence speed and accuracy within subarrays, enhancing the algorithm's compatibility across laser arrays of varying scales. We have validated the feasibility of the distributed CBC architecture through numerical analysis and assessed the strategy's performance in both static and dynamic environments using simulation software. The simulation findings indicate that, compared to traditional CBC systems, distributed architecture with 3, 7, and 19 subarrays and utilizing the piecewise SPGD algorithm, has experienced phase control bandwidth enhancements by factors of approximately 3.6, 10.4, and 32.5 respectively, maintaining superior average power output in dynamic noise environments. The proposed architecture and strategy also accommodate subarrays of variable scales and obviates the necessity for large-aperture optical components on the emitted plane, demonstrating exceptional scalability and adaptability.

Morphology-independent general-purpose optical surface tractor beam

Optical tractor beams capable of pulling particles backward have garnered significant and increasing interest. Traditional optical tractor beams are limited to free space beams with small forward wavevectors, enabling them to pull selected particles. Here, we present a comprehensive theory for the optical force exerted by a surface wave using analytical and numerical calculations, revealing the relationship between the canonical momentum and optical forces. Based on this theory, we demonstrate a general purpose optical surface tractor beam that can pull any passive particle, regardless of size, composition, or geometry. The tractor beam utilizes a surface wave with negative canonical momentum characterized by a single well-defined negative Bloch k vector. The tractor beam relies on a mechanism where the negative incident force always surpasses the recoil force. As such, the tractor beam, when excited on the surface of a double-negative index metamaterial, can pull particles with different morphologies.

Bessel-Beam Single-Photon High-Resolution Imaging in Time and Space

Synchronous laser beam scanning is a common technique used in single-photon imaging where the spatial resolution is primarily determined by the beam divergence angle. In this context, Bessel beams have been investigated as they can overcome the diffraction limit associated with traditional Gaussian beams. Notably, the central spot of a Bessel beam retains its size almost unchanged within a non-diffractive distance. However, the presence of sidelobes in the Bessel beam can negatively impact spatial resolution. To address this challenge, we have developed a single-photon imaging system with high-depth resolution, which allows for the suppression of echo photons from the sidelobe light in the depth image, particularly when their flight time differs from that of the central spot. In our LiDAR setup, we successfully achieved high-resolution scanning imaging with a spatial resolution of approximately 0.5 mm while also demonstrating a high-depth resolution of 12 mm.

Scattering of a Bessel Pincer Light-Sheet Beam on a Charged Particle at Arbitrary Size.

Electromagnetic scattering is a routine tool for rapid, non-contact characterization of particle media. In previous work, the interaction targets of scattering intensity, scattering efficiency, and extinction efficiency of Bessel pincer light-sheet beams were all aimed at dielectric spheres. However, most particles in nature are charged. Considering the boundary condition on a charged sphere, the beam shape coefficients (BSCs) (pmn,qmn) of the charged spherical particle illuminated by a Bessel pincer light-sheet beam are obtained. The extinction, scattering, and absorption efficiencies are derived under the generalized Lorenz-Mie theory (GLMT) framework. This study reveals the significant differences in scattering characteristics of Bessel pincer light-sheet beams on a charged particle compared to traditional beams. The simulations show a few apparent differences in the far-field scattering intensity and efficiencies between charged and natural spheres under the influence of dimensionless size parameters. As dimensionless parameters increase, the difference between the charged and neutral spheres decreases. The effects of refractive index and beam parameters on scattering, extinction, and absorption coefficients are different but tend to converge with increasing dimensionless parameters. When applied to charged spheres with different refractive indices, the scattering, extinction, and absorption efficiencies of Bessel pincer light-sheet beams change with variations in surface charge. However, once the surface charge reaches saturation, these efficiencies become stable. This study is significant for understanding optical manipulation and super-resolution imaging in single-molecule microbiology.