A simple method for mitigating error in the fixed-offset of a double-crystal monochromator

In order to maintain a constant monochromatic synchrotron X-ray beam height for all energies, the separation between the crystals of a double-crystal monochromator is typically adjusted, via translation of the second crystal, while X-ray energy is varied, via rotation of the crystal pair. The ability to accurately translate the second crystal requires precise knowledge of the separation between the two crystals and, when present, crystal miscuts. Here, a simple method for calibrating the crystal gap from measured variation in the X-ray beam height that eliminates error in the fixed beam offset is provided.

Static Metasurface Reflectors with Independent Magnitude and Phase Control using Coupled Resonator Configuration

<div>A static metasurface reflector based on a novel coupled resonator configuration is proposed to independently control</div><div>the reflection phase and magnitude of linearly polarized incident fields, and is demonstrated experimentally in the millimeter-wave Ka-band around 30 GHz. The proposed concept is illustrated using a unit cell design consisting of a rectangular ring coupled with a rectangular slot resonator backed by a grounded dielectric slab. By geometrically tuning various dimensions of the two resonators, a near-perfect amplitude-phase coverage is achieved at a fixed design frequency of 30 GHz. To demonstrate the flexible beam-forming capability of the proposed metasurface reflectors, illustrative examples of fixed beam steering with varying reflection magnitudes, and asymmetric dual-beam patterns with specified reflection magnitude, reflection angles and beam-widths, are successfully shown. Compared to the standard method based on polarization rotation and resistive loadings with discrete values, the proposed technique does not generate undesired cross-polarization field reflection, and provides a continuous magnitude tuning including full absorption, along with wide phase coverage.</div>

Static Metasurface Reflectors with Independent Magnitude and Phase Control using Coupled Resonator Configuration

<div>A static metasurface reflector based on a novel coupled resonator configuration is proposed to independently control</div><div>the reflection phase and magnitude of linearly polarized incident fields, and is demonstrated experimentally in the millimeter-wave Ka-band around 30 GHz. The proposed concept is illustrated using a unit cell design consisting of a rectangular ring coupled with a rectangular slot resonator backed by a grounded dielectric slab. By geometrically tuning various dimensions of the two resonators, a near-perfect amplitude-phase coverage is achieved at a fixed design frequency of 30 GHz. To demonstrate the flexible beam-forming capability of the proposed metasurface reflectors, illustrative examples of fixed beam steering with varying reflection magnitudes, and asymmetric dual-beam patterns with specified reflection magnitude, reflection angles and beam-widths, are successfully shown. Compared to the standard method based on polarization rotation and resistive loadings with discrete values, the proposed technique does not generate undesired cross-polarization field reflection, and provides a continuous magnitude tuning including full absorption, along with wide phase coverage.</div>

Free Vibration Analysis Of Layered Beams With Delamination Damage-An ANSYS®-Based FEM Investigation

Identifying delamination has been a focal point for many researchers. The reason for this interest arises from criticality of delamination in a variety of industries: automotive, aerospace, and construction. Therefore, vibration-based damage identification method is applied to detect, locate and characterize the damage in a mechanical structure. In this method, natural frequency as a diagnostic tool to determine the integrity of a structure has been utilized. The current research presents a FEM-based investigation into free vibrational analysis of defective layered beams with free mode delamination. It is shown that the size, type and location of delamination directly influence system non-dimensional frequencies. Based on an existing 1D model, the investigation is extended to 2D modelling for single-and-double-delamination cases. In each case, Fixed-Fixed and cantilevered beam configurations, both centred and off-centred delamination conditions are studied. Further, a 3D model is also developed for single delamination of a Fixed-Fixed beam. All simulation results show excellent agreement with the data available in the literature. The ANSYS ® FEM-based modelling approach presented here is general and accurately predicts delamination effects on the frequency response of beam structures.

Free Vibration Analysis Of Layered Beams With Delamination Damage-An ANSYS®-Based FEM Investigation

Identifying delamination has been a focal point for many researchers. The reason for this interest arises from criticality of delamination in a variety of industries: automotive, aerospace, and construction. Therefore, vibration-based damage identification method is applied to detect, locate and characterize the damage in a mechanical structure. In this method, natural frequency as a diagnostic tool to determine the integrity of a structure has been utilized. The current research presents a FEM-based investigation into free vibrational analysis of defective layered beams with free mode delamination. It is shown that the size, type and location of delamination directly influence system non-dimensional frequencies. Based on an existing 1D model, the investigation is extended to 2D modelling for single-and-double-delamination cases. In each case, Fixed-Fixed and cantilevered beam configurations, both centred and off-centred delamination conditions are studied. Further, a 3D model is also developed for single delamination of a Fixed-Fixed beam. All simulation results show excellent agreement with the data available in the literature. The ANSYS ® FEM-based modelling approach presented here is general and accurately predicts delamination effects on the frequency response of beam structures.

Numerical Solution of Bending of the Beam with Given Friction

We are interested in a contact problem for a thin fixed beam with an internal point obstacle with possible rotation and shift depending on a given swivel and sliding friction. This problem belongs to the most basic practical problems in, for instance, the contact mechanics in the sustainable building construction design. The analysis and the practical solution plays a crucial role in the process and cannot be ignored. In this paper, we consider the classical Euler–Bernoulli beam model, which we formulate, analyze, and numerically solve. The objective function of the corresponding optimization problem for finding the coefficients in the finite element basis combines a quadratic function and an additional non-differentiable part with absolute values representing the influence of considered friction. We present two basic algorithms for the solution: the regularized primal solution, where the non-differentiable part is approximated, and the dual formulation. We discuss the disadvantages of the methods on the solution of the academic benchmarks.

Numerical Analysis of the Beam-Column Resistance Compared to Methods by European Standards

The optimisation of the design method for verification of slender steel beam-columns is still a current issue not only from scientific point of view, but also for design practice. Therefore, the main objective of this paper is comparison of the suitability of established design approaches, according to the European standards for steel and aluminium structures, on the basis of numerical simulations. Thus, a finite element model was validated on the basis of experimental analysis available in the scientific literature. To perform the comparison of accuracy of design approaches according to European standards, a commercial software program ANSYS was used for observation of the resistances of beam-columns. The resistance of european I beams with parallel flanges (IPE) and a rectangular hollow cross-section (RHS) were investigated for four load cases on a simply supported member and also on a pinned-fixed beam column with linear bending moment distribution, where the resistance of the cross-section governs. Finally, the conclusions for suitability of the respective design approaches are discussed, together with some findings that arose from this work.