Angle Sections Research Articles

Entanglement-assisted multi-aperture pulse-compression radar for angle resolving detection

Entanglement has been known to boost target detection, despite it being destroyed by lossy-noisy propagation. Recently, Zhuang and Shapiro (2022 Phys. Rev. Lett. 128 010501) proposed a quantum pulse-compression radar to extend entanglement’s benefit to target range estimation. In a radar application, many other aspects of the target are of interest, including angle, velocity and cross section. In this study, we propose a dual-receiver radar scheme that employs a high time-bandwidth product microwave pulse entangled with a pre-shared reference signal available at the receiver, to investigate the direction of a distant object and show that the direction-resolving capability is significantly improved by entanglement, compared to its classical counterpart under the same parameter settings. We identify the applicable scenario of this quantum radar to be short-range and high-frequency, which enables entanglement’s benefit in a reasonable integration time.

Enhancement of the Lateral Performance of RC Columns Using Steel Jacketing: A Numerical Approach

Steel jacketing has become an attractive strengthening technique for reinforced concrete (RC) columns due to ease of construction and less space requirement. The steel cage consists of angle sections placed at corners and held together by battens at intervals along the RC column height. A numerical investigation of the effective use of steel jackets as a strengthening technique in RC columns is presented in this paper. First, the finite element models of the strengthened column were developed and validated using past experimental data. Then, with the validated model, six sets of steel jacket sections with modified cross-sections such as batten spacing, batten thickness, batten width, end batten width, L angle thickness and steel jacket height were tested under constant axial and lateral loading to understand the effectiveness of steel jackets as the strengthening technique. AnunstrengthenRC column were also analysed to compare the performance of a similar column strengthened by steel jackets with modified parameters. It was shown that strengthening RC columns with steel jackets was effective in enhancing the lateral performance of the columns and resulted in a more stable load-displacement curve with lower strength degradations as compared with the un-strengthened ones. Additionally, it was found that the most effective method to increase the lateral strength and ductility is increasing the L angle thickness. On the other hand, increasing the steel jacket height also increases the lateral performance, however, it was identified that increasing the jacket height is effective only up to 1/3rd of the RC column height. Finally, the obtained results for each parameter were compared to study the behaviour of each component of the steel jacket towards lateral strength and ductility improvements.

High Enthalpy Non-Equilibrium Expansion Effects in Turbulent Flow of the Conical Nozzle

High enthalpy stagnation gas can be converted into hypervelocity flow through the contraction—expansion nozzle. The enthalpy flow in the nozzle can be divided into three regions: an equilibrium region, a non-equilibrium region, and a frozen region. The stagnation gas with a total enthalpy of 13.4 MJ/kg is used to analyze the thermochemical non-equilibrium effects. At the selected conditions, the effects of a conical nozzle under different expansion angles of the expansion section, curvature radius of the throat, throat radius, and convergence angle of the convergent section are investigated. Based on the Spalart–Allmaras one-equation turbulence model with the Catris–Aupiox compressibility correction, a multi-block solver for axisymmetric compressible Navier–Stokes equations is applied to simulate the thermochemical non-equilibrium flow in several high enthalpy conical nozzles. The multi-species two-temperature equation is employed in the calculation. The results reveal three interesting characteristics: Firstly, the thermochemical non-equilibrium effects are sensitive to the maximum expansion angle and throat radius but not to the radius of throat curvature and contraction angle. Secondly, as the maximum expansion angle decreases and the throat radius increases, the flow approaches equilibrium state. When the maximum expansion angle decreases from 12° to 4°, the freezing temperature decreases from 2623 K to 2018 K. When the throat diameter increased from 10 mm to 30 mm, the freezing temperature decreased from 2442 K to 2140 K. Finally, the maximum expansion angle and throat radius not only affect the position of the freezing point but also the flow field parameters, such as temperature, Mach number, and species mass fraction.

Testing, FE modelling and design of pin-ended stainless steel equal-leg angle section columns and beam–columns

The behaviour and design of pin-ended stainless steel equal-leg angle section members under compression and compression plus minor-axis bending are investigated herein. The studied members are cylindrically pinned about the minor axis. An experimental investigation, including material testing, initial geometric imperfection measurements and physical tests on hot-rolled stainless steel equal-leg angle section members is first presented. Numerical models are developed and validated against the new experimental data. A numerical parametric study is then presented considering both hot-rolled and cold-formed stainless steel angle section columns alongside beam–columns with a wide range of slenderness values. Finally, new design proposals for pin-ended stainless steel equal-leg angle section members under compression and combined compression and minor-axis bending are developed and verified against the results of existing physical experiments, as well as the newly-generated test and numerical results. The proposed design rules are shown to offer substantially more accurate and consistent resistance predictions compared to existing codified design rules. The reliability of the new design provisions, with a recommended partial safety factor γM1=1.1, is verified following the EN 1990 procedure.

A new predictor of the optimal pulmonary artery reconstruction method during the arterial switch operation.

To more accurately predict the optimal pulmonary artery (PA) reconstruction procedure (Lecompte manoeuvre or original Jatene procedure) during the arterial switch operation (ASO), we focused on the horizontal sectioning (HS) angle between the left hilum PA and the great arteries using preoperative computed tomography (CT) imaging. We defined the HS angle α (β) as the angle between the tangential line from the posterior (anterior) wall of the left PA at the hilum to the left anterior (right posterior) surface of the main PA and the tangential line from the left surface of the ascending aorta to the left anterior (right posterior) surface of the main PA. We identified 14 consecutive patients diagnosed with transposition of the great arteries (TGA) or TGA-type double-outlet right ventricle who underwent preoperative CT imaging. The original Jatene or Lecompte procedure was used for nine (OJ group) and five (L group) patients. Relationships of the great arteries of the OJ and L groups were side-by-side in eight and two patients, oblique in one and one patient, and anteroposterior in zero and two patients, respectively. In the OJ group, β was greater than α in all patients. The median α/β value was 0.618. In group L, α was greater than β in all patients. The median α/β was 1.307. Left PA stenosis caused by stretching was not observed in the L group. Coronary obstruction was not identified in the OJ group. Left PA stenosis behind the neo-ascending aorta was observed in one patient in the OJ group and required reoperation. The HS angle may be a useful predictor of optimal intraoperative PA reconstruction during ASO, especially for side-by-side or oblique relationships.

Material properties and local stability of WAAM stainless steel equal angle sections

An experimental study has been carried out to investigate the material properties and local stabilities of outstand WAAM 316L stainless steel plates. A series of equal angle section (EAS) stub columns and corresponding sample plates for tensile coupon extraction were fabricated employing two sets of manufacturing parameters in order to achieve two print thicknesses. The tensile coupons were extracted from the sample plates along different printing directions, and the tensile test results indicated a high degree of anisotropy while displaying satisfactory material ductility according to the Eurocode 3 requirements. The EAS stub columns covered a wide range of plate slendernesses and their geometric profiles were 3D laser scanned and analysed prior to the compression tests. The failure modes and load carrying capacities of the WAAM EAS stub columns were analysed, showing generally lower resistances compared to conventional rolled counterparts in the high slenderness range. Assessed against the test data, the Continuous Strength Method is shown to be suitable for designing stocky WAAM stainless steel plates. For the design of slender WAAM stainless steel plates, the effective width equation in Eurocode 3 is shown to be applicable, however, the calculation should be based on the new characteristic geometric dimension proposed. Based on this, it is further demonstrated that the thicker printing strategy adopted in the current study would have a higher effective thickness to overall thickness ratio, hence more efficient builds than the thinner printing strategy.

Study on the Head Loss of the Inlet Gradient Section of the Aqueduct

The form of the inlet section of aqueducts that connect the upstream channel and the downstream channel affects the flow pattern and head loss. In order to provide a reference for the design of the gradient section of water-transfer channels, a typical three-dimensional hydrodynamic model is established in this paper based on existing results. The results show that the local head loss coefficient is related to the cross-sectional area of the inlet and outlet of the gradient section, the water surface contraction angle of the gradient section, and the elevation difference between the bottoms of the inlet and outlet of the gradient section, and a functional relationship is provided; when changing the width of the inlet and outlet bottoms, the local head loss coefficient is negatively related to the water surface contraction angle and increases with the increase in Wup/Wdown; the local head loss coefficient has a good exponential function with Wup/Wdown. The research results can provide a reference for the design of the inlet gradient section and the solution of the head loss coefficient.

Campbell diagrams, dynamics and instability zones of graphene-based spinning shafts

Carbon-based nanocomposite drive shafts have received considerable attention because of their excellent material and mechanical properties, with applications in modern aerospace, automotive industries and others. Therefore, for the first time, new Campbell diagrams, vibration and bifurcation points for multilayer shafts reinforced with three technologically justified distribution patterns of graphene nanoplatelets (GPLs) in the polymer matrix are presented and examined. A new formulation in the framework of a modified Timoshenko beam theory making use of the rotation angles of the cross sections of the shaft with five degrees of freedom is utilized. The modulus of elasticity of the nanocomposite material is estimated using the Halpin-Tsai micromechanical model, whereas the mass density and Poisson's ratio are computed by means of the law of mixtures. Hamilton's variational principle is used to derive weak and strong forms of motion equations of the shaft with classical and mixed boundary conditions. Assumptions for the derived model of the nanocomposite shaft are presented to clearly describe the mechanical state of the system. The Ritz-Chebyshev method is applied to discretize the governing equations and obtain the generalized nonlinear characteristic equations in matrix form including the gyroscopic effect and elastic stiffness caused by the rotation of the shaft. Verification of obtained results and convergence study were performed to show the correctness and advantages of the proposed solution method. The effect of different key parameters such as GPLs distribution and weight percentage, axial speed of the shaft, and boundary conditions, on its global damping, dynamics and instability zones are shown. For the first time, it is clearly shown how studied factors affect the shape of Campbell diagrams as well as the shift of natural frequency and bifurcation point of the graphene-based nanocomposite shafts.

Behaviour of back-to-back built-up cold-formed steel equal angles with complex edge stiffeners under axial compression

The application of built-up cold-formed steel (CFS) structures becoming popular in civil engineering fields such as trusses, bridges, transmission towers and railway coaches. This work presents the numerical analysis of axially compressed back-to-back built-up CFS equal angle sections. A nonlinear finite element (FE) model was developed that considered geometric imperfections, material nonlinearity, and intermediate fastener. The published experimental test data were used to compare the FE model, and the results shown good agreement. The effect of the slenderness ratio and edge stiffening direction on the axial strength of back-to-back built-up CFS equal angle sections is investigated by using parametric study.

Comparative analysis of transmission line towers for angle section and square hollow section structural configuration in Indian context

With increase in the electric energy consumption, there has always been a need to reduce cost required to produce as well as transport it with least impact on the environment, the prime method of transferring the electric power being Transmission Line Towers. The most common and majorly dominating structural configuration used for Transmission Line Towers in Indian region is Angle Sections. This study is an attempt to introduce a new section configuration: Square Hollow Sections, having a notable impact in properties of Transmission Line Towers positively in comparison with the angle – section Transmission Line Towers. The guidelines for calculating member capacity of an Angle – section Transmission Line Towers is stated in Indian Standard Codal Provision, IS 802: 1995 (Part 1), Section 2. However, since there is no provision laid for the determination of same in case of a Square Hollow Section, IS 800: 2007 is used to determine the capacity of a Square Hollow Section – Transmission Line Towers. For carrying out the comparative study, a Twin – Conductor Tower is taken into consideration, located in Wind Zone V as per Indian Context. While conducting the analysis, all the other parameters remained constant, other than the legs of the structural configuration of transmission towers as they contribute a major impact in the overall properties of the towers. The analytical tool used for carrying out the analysis is STAAD Pro. Connect Edition. The loading conditions on the towers are applied as per the provisions laid in IS 802: 1995 (Part 1). The study yields that with an increase in Rv values of square hollow section, the overall redundancy of the tower structure had been reduced, thereby reducing the area of the application of wind loads on the structure, making the same an optimized solution for a comparative less – weight, economical with same power transmission, tower structural configuration.

Experimental study on the flexural performance of steel-concrete composite section of self-anchored suspension bridge

In order to study the flexural performance of the steel-concrete composite section of self-anchored suspension bridge, a test model of the steel-concrete composite section was fabricated according to the scale of 1 : 3 based on the Wushui Bridge, and a four-point negative bending test was carried out. The results show that the residual displacement ratio is 0.7%, and the experimental model is in the elastic stage under the design load condition, which incidate that the component is safe under normal service condition. Under the overloading condition, the residual displacement ratio is 19%, the experimental model is in the elastic-plastic stage, but the stress of materials still meets the requirements. Under the two conditions, the deformation angle of the composite section is small and the stiffness transition is stable. The relative slip between the steel plate and concrete in the composite section is small (no more than 0.25 mm). The stress in the top steel plate and bottom steel plates of the composite section are gradually decreases during the transfer from the steel stiffening beam to the concrete side. The design of the steel-concrete composite section is reasonably loaded, and the mechanical properties are smoothly transferred.

Material Selection Analysis of UHV AC Double Circuit Steel Pipe Tower Cross Arm Structure

The cross arm of wire is an important part of the UHV tower, and the force and calculated length of the upper and lower main or inclined materials are smaller than the main or inclined materials of the tower, and the two types of section types, Angle steel, and steel pipe, have their own advantages and disadvantages. How to select materials reasonably and give full play to their advantages is an important content of the optimization design of the tower structure. In this paper, the double circuit steel pipe tower of the same UHV project tower is taken as an example, and the main material of the cross arm and the inclined material are selected Angle steel or steel pipe. The research shows that the main material of the cross arm is Angle steel, the main material of the cross arm is suggested to be steel pipe, the front inclined material of the cross arm is steel pipe, and the material selection principle of the cross arm can provide a reference for the future engineering design.

Определение участка нарезания мелкомодульных зубьев в эксцентриковых механизмах свободного хода

Normal forces use to transfer the load makes it possible to increase load capacity and reliability of the free running mechanisms. Normal forces in the eccentric free running mechanisms are realized in engagement of the fine-module teeth that are cut on the outer cage inner surface and the outer surface of the eccentric rings. To ensure correct operation of the mechanism in jamming and wedging, value of the fine-module teeth cutting section angle should be selected from the equality condition of the radial clearance between the outer cage teeth and the eccentric ring in the entire working section. To solve the problem, calculation scheme is proposed and mathematical model is obtained that describes relationship between the fine-module cutting section angle and the mechanism geometric parameters. The nature of the main geometric parameters influence (radius, eccentricity, radial clearance, module, etc.) on the value of the teeth cutting section angle was established. It is shown that eccentricity provides the greatest influence on the working area size, radial clearance and module influences are less pronounced.

The divergent angle of cavitational devices influences melanoidin degradation. A new look through experimental and computational analysis

In the present work, the influence of the divergent section angle of hydrodynamic cavitation (HC) devices on melanoidin degradation was investigated. The HC reactor was operated alone and in combination with an oxidant at four concentrations of H2O2: 0.9, 2.8, 4.7, 6.6 g L−1. Five Venturi devices (with divergent angles of 4°, 8°, 11°, 14°, and 90°) were made and analyzed at five operating pressures (150, 300, 440, 600, 760 kPa) for a period of 30 min. ANOVA and Fisher's LSD method were used to define the best angle and the best operating pressure for melanoidin degradation. The highest efficiency of melanoidin degradation (14.32 %) was obtained with an angle of 11° and a pressure of 600 kPa. Computational Fluid Dynamics (CFD) simulations were performed to study the influence of the divergent angle on the flow parameters. They showed that at smaller angles (4° and 8°) there was an excess growth of cavities, increasing the chance of coalescence of cavities and reducing the intensity of collapse. On the other hand, at a very high angle (90°), the cavities collapsed before growing, releasing less energy at the time of implosion. The degradation efficiency increased to 60.84 % when 2.8 g L−1 of H2O2 was applied to the HC reactor, at pH 2.5. Higher concentrations of H2O2 reduced the degradation efficiency, indicating a “scavenging” effect in combined systems (HC + H2O2) due to the generation of unreactive radicals. The present study demonstrated that the combination of HC + H2O2 is a promising alternative for melanoidin degradation, with the divergent angle of the device being an important parameter of this treatment process.

A Load-Carrying Capacity Evaluation Method for the Welded Joints of Rocket Engine Frame

The load-carrying capacities of welded joints need to be paid attention to in the design of the frame, which transfers the thrust generated by the rocket engine to the rocket body. A load-carrying capacity evaluation method of welded joints based on the structural stress method is proposed in this study. Both the ultimate load-carrying capacity and fracture section angle are precisely obtained by the evaluation method. At the same time, a definition of weld-failure stress is given based on the evaluation method and tests. The load-carrying capacity of welded joints in the rocket engine frame is analyzed through the finite element model, including the overall structure and local weld details. The weld-failure stress of welded joints is obtained based on the analysis of three types of welded structures—standard shear specimen, U-shaped fillet welded specimen and pipe-plate fillet welded specimen. The safety factors of the transverse rod and longitudinal bearing rod welded joints of the frame are 8.6 and 13.4, respectively.

Visualization and quantification of coconut using advanced computed tomography postprocessing technology.

Computed tomography (CT) is a non-invasive examination tool that is widely used in medicine. In this study, we explored its value in visualizing and quantifying coconut. Twelve coconuts were scanned using CT for three months. Axial CT images of the coconuts were obtained using a dual-source CT scanner. In postprocessing process, various three-dimensional models were created by volume rendering (VR), and the plane sections of different angles were obtained through multiplanar reformation (MPR). The morphological parameters and the CT values of the exocarp, mesocarp, endocarp, embryo, bud, solid endosperm, liquid endosperm, and coconut apple were measured. The analysis of variances was used for temporal repeated measures and linear and non-linear regressions were used to analyze the relationship between the data. The MPR images and VR models provide excellent visualization of the different structures of the coconut. The statistical results showed that the weight of coconut and liquid endosperm volume decreased significantly during the three months, while the CT value of coconut apple decreased slightly. We observed a complete germination of a coconut, its data showed a significant negative correlation between the CT value of the bud and the liquid endosperm volume (y = -2.6955x + 244.91; R2 = 0.9859), and a strong positive correlation between the height and CT value of the bud (y = 1.9576 ln(x) -2.1655; R2 = 0.9691). CT technology can be used for visualization and quantitative analysis of the internal structure of the coconut, and some morphological changes and composition changes of the coconut during the germination process were observed during the three-month experiment. Therefore, CT is a potential tool for analyzing coconuts.

Analytical Solution and Exact Effective Thickness of Multilayered Laminated Glass Cantilevered Balustrades

Abstract Cantilevered laminated glass balustrades present design challenges. The cross-sectional warping allowed by the end constraint induces such strong asymmetrical deformations that traditional methods, defining the effective thickness of a monolith with equivalent bending properties, cannot be accurate. By using a recently proposed refined zig-zag theory for laminates, we analytically solve the representative problem of a short simply supported laminated beam with a long cantilevered overhang. The variables are the beam displacement and the mean sectional shear angle, defining the zig-zag warping of the cross section. Geometric and natural boundary conditions, as well as the matching condition at the intermediate roller constraint, necessary to solve the governing differential problem, are found variationally. The analytical solutions under concentrated and distributed loads exactly determine the effective thickness of the laminate. Comparisons are made with other approaches that that, however, apply only to three-layered packages. The expressions proposed here can be directly used in the design practice.

Evaluating the optimum electric power consumption for forced convection of an EHD induced circulating flow through a circular tube: A numerical study

In this study, the effect of using EHD forced convection heat transfer through a circular tube is numerically investigated to prepare the required data sets to find the optimum configuration considering the Nusselt number and friction factor. To gain the required results, the Reynolds numbers and the applied voltages are set to 3000–7000 and 9–13.5 kV, respectively. Moreover, the variety of using miscellaneous placement positions of the central wire emitter, up to 30%, in combination with collector section angles in the range of θ = 90°–360°, are simultaneously investigated. The results of different section angles show that the Nusselt number has increased between 2.35 and 4.76 times compared to the non-EHD mode. Similarly, for the various eccentricities, the Nusselt number has increased between 2.35 and 5.05 times. In the final step, upon the gathered data, a Pareto front of optimal points was deduced for the hydraulic-thermal performances against the power consumption, and the optimum design was highlighted.

Comparison of design specification of steel single unequal angle section used as beams/purlins subjected to biaxial bending moment by various standard codes using Abaqus software

Comparison of design specification of steel single unequal angle section used as beams/purlins subjected to biaxial bending moment by various standard codes using Abaqus software

Crushing performance of pultruded GFRP angle section with various connections and joints on lattice towers

Crushing performance of pultruded GFRP angle section with various connections and joints on lattice towers