Beam System Research Articles

Effect of non-rare-earth element enrichment on in-the-column secondary electron image contrast of Nd-rich phases in Nd-Fe-B sintered magnets

In-the-column secondary electron (SE) imaging has demonstrated an important role in identifying various Nd-rich phases in Nd-Fe-B sintered magnets at a microscale field of view. It is well known that modifying the microstructure of Nd-Fe-B sintered magnets by adding non-rear-earth (NRE) elements dissolved into the intergranular Nd-rich phases during post-sinter annealing can effectively increase the magnet coercivity. However, the effect of NRE element enrichment on in-the-column SE image contrast of Nd-rich phases has not received much attention. In this study, we have combined a focused ion/electron dual beam system (FIB/SEM) and a scanning/transmission electron microscope (S/TEM) to investigate the in-the-column SE image contrast, structure, and element distribution of intergranular Nd-rich phases in commercial heavy-rare-earth (HRE) free Nd-Fe-B sintered magnets. In-lens SE imaging revealed that Cu, Co, or Al-enriched neodymium oxides with fcc, Ia3¯-type, or amorphous structures are brighter than the Nd2Fe14B matrix at an accelerating voltage of 2 kV and a working distance of 4 mm. Bright stripes inside the intergranular fcc NdOx were also visible in high-resolution through-the-column SE imaging, reflecting the nanoscale composition variation with Co or Cu enrichment. Contrarily, at the same imaging conditions, the nearly pure fcc NdOx and Ia3¯-Nd2O3 exhibit darker than the Nd2Fe14B matrix in the in-lens SE image. It has been demonstrated that the in-lens SE image contrast of Nd-rich phases with respect to the Nd2Fe14B matrix remains constant by systematically adjusting the accelerating voltage from 2 kV to 5 kV and the working distance from 4 mm to 6 mm. Our research results suggest that low-voltage in-the-column SE imaging could be used to track element diffusion in triple junction and grain boundary Nd-rich phases of Nd-Fe-B sintered magnets during post-sinter annealing by in-situ MEMS heating in SEM.

Prospect for measurements of (γ, n) reaction cross-sections of p-nuclei at ELI-NP

The gamma beam system under construction at the ELI-NP facility in Romania is projected to give the nuclear physics community access to an experimental system providing a high-intensity, narrow bandwidth photon beam at variable energy. With high-efficiency detector systems in place, the experimental programme will have a strong potential for in-depth studies of rare stable isotopes originating from the astrophysical p-process. In particular, the neutron detection systems are already implemented through a dedicated 3He long neutron counter array, called ELIGANT-TN, that is completed and in use. In this mini-review, we will give a summary of the current status of existing (γ, n) cross-section data, as well as the methods to obtain them, and highlight the future potential to expand and improve such data using the ELI-NP instrumentation and beam-lines.

Development of a high-voltage stabilization system for precision ion beams

A new system to precisely control the accelerating voltage of an electrostatic accelerator has been developed. With this development, the acceleration voltage stability ΔV/V in the low-frequency range was successfully controlled to 6.0 × 10−5. In this development, the cause of the voltage fluctuation of the acceleration voltage was investigated. As a result, it was found that noise components due to mechanical vibration existed. Therefore, the HVD (High-Voltage Divider) feedback method, which is less susceptible to mechanical vibration, was adopted and the effect of vibration was successfully eliminated. Furthermore, by adding a high-sensitivity CPO feedback system in place of the previously used slit feedback system, low-frequency voltage fluctuations were eliminated, and high acceleration voltage stability could be obtained even in beamlines without a slit system.

Microstructural Analysis of Solid Oxide Electrochemical Cells via 3D Reconstruction Using a FIB-SEM Dual Beam System

The 3D reconstruction based on tomography technology enables quantitative and qualitative microstructural analysis of complex multiphase oxide structures. This powerful approach is widely investigated in diverse areas, in particular, gaining more importance in solid oxide electrochemical cells (SOCs) fields. SOCs are promising energy conversion devices with high efficiency, however, they have complex and porous/dense multilayered microstructures, which are closely related to the electrochemical reaction in the electrodes, thus, one of the major factors determining overall output performance of SOCs. Therefore, it is necessary to quantify the microstructural parameters of the cell. A focused ion beam-scanning electron microscope (FIB-SEM) dual beam system is one well-established method to obtain tomographic images to reconstruct 3D microstructures. It has an appropriate scale of tenth of nm to μm-level with high spatial resolution to represent the microstructural characteristics of the SOC electrodes. This presentation is intended to introduce our progress on 3D reconstruction techniques to quantitatively analyse SOCs, obtaining microstructural features such as particle size, connectivity, tortuosity, contact area, and triple phase boundary density. These in-depth analyses are helpful in extensively understanding electrochemical behavior in SOC electrodes.

Deflection of a Partially Composite Beam Considering the Effect of Shear Deformation

In this research, the deflection in the interface of a partially composite beam considering the effect of shear deformation is deter-mined. The system of beams is structured by two beams of prismatic sections, connected by an adhesive very thin and rigid, subjected to a uniform bending moment and a uniformly distributed load. The governing differential equation of the partially composite beam is obtained from the total functional energy that takes into consideration the shear deformation. The extreme moments creating second moments, shear forces and normal forces are applied to each beam. The differential equation is derived and then, compared to the one found in partial composite beams where the shear deformation is neglected. It is shown that the theoretical results of deflection with and without shear deformation are compared to each other and also with those found in the Timoshenko’s beam theory.

Design of Linear Quadratic Regulator Based on Genetic Model Reference Adaptive Control

As the conventional control system is a controller that controls or regulates the dynamics of any other process. From time to time, this control system may not behave appropriately online; this is because of many factors like some variation in the dynamics of the process itself or unexpected changes in the environment, or even undefined parameters of the system model. To overcome the problem above, an adaptive controller is designed and implemented. This paper discusses the design of a controller for a ball and beam system with Genetic Model Reference Adaptive Control (GMRAC) for adaptive mechanism with the MIT rule. Parameter adjustment (selection) should be done using optimization methods in order to obtain an optimal performance, so genetic algorithm. (GA) will be used as an optimization method to obtain the optimum values for these parameters. As the controller, a Linear quadratic regulator (LQR) controller will be used as it is one of the most popular controllers, the performance of the proposed controller with the ball and beam system will be carried out with MATLAB Simulink in order to evaluate its effectiveness. The results show satisfactory performance where the position of the ball tracks the desired model reference.

Dynamics of moving coupled objects with stabilizers and unconventional couplings

A comprehensive investigation was carried out to analyze the vibration stability of a coupled bogie system moving uniformly along a complexly modeled flexibly supported infinite high-order shear deformable coupled beam system on a viscoelastic base. The main contribution of this study involves a comparative analysis of the specific coupling of the bogie system with and without the proposed additional stabilizer, in comparison to conventional cases. The study demonstrates significant benefits of the newly proposed options of dual coupling and additional stabilizers in terms of stability. Another contribution of the study is the feasibility of the proposed unconventional models in technical practice. A phenomenon has been discovered that increasing the viscous damping in a special coupling leads to the occurrence of motion instability in the mechanical system. The paper also presents a novel technical solution for connecting moving objects at high speeds. The benefits of the additional oscillator as a stabilizer are extensively illustrated through numerous different examples. It is well-known that when the velocity of masses, such as the bogie or any other complex oscillator, exceeds the minimum velocity at which waves propagate in the beam, the oscillation of the system may become unstable. Therefore, it is crucial to determine the conditions and stable regions of motion that involve specific combinations of system parameters. The region of instability is identified within the parameter space of the system using the D-decomposition technique and the argument principle. The bogie is specifically connected to another bogie in two new ways: with an additional stabilizer allowing double transverse displacement and providing an additional contact with the base, or with a specific coupling that enables simultaneous rotational and transverse displacement at the contact point. The analysis reveals two key findings. First, the additional mechanical stabilizer allows for the widest range of permissible suspension stiffness (largest stability region) when the connection is conventional. Second, enabling transverse displacement in the couplings results in a stable regime of motion at much lower suspension stiffness compared to other cases.

Designing and implementing a Proportional Derivative-based Controllers for Ball and Beam Systems

Designing and implementing a Proportional Derivative-based Controllers for Ball and Beam Systems

Inverse design of omnidirectional coherent absorbers for optical power beaming applications.

An efficient photovoltaic power converter is a critical element in laser power beaming systems for maximizing the end-to-end power transfer efficiency while minimizing beam reflections from the receiver for safety considerations. We designed a multilayer absorber that can efficiently trap monochromatic light from broad incident angles. The proposed design is built on the concept of a one-way coherent absorber with inverse-designed aperiodic multilayer front- and back-reflectors that enable maximal optical absorption in a thin-film photovoltaic material for broad angles. We argue that the broad bandwidth is achieved through an optimization search process that automatically engineers the modal content of the cavity to create multiple overlapping resonant modes at the desired angle or frequency range. A realistic design is provided based on GaAs thin films with inverse-designed multilayer binary AlAs/AlGaAs mirrors. The proposed device can pave the way for efficient optical power beaming systems.

Experimental Study on Performance of Impact Damper For Various Mass Ratios

Vibration plays a vital role in many structural elements. Excessive vibration can cause failure due to resonance and fatigue, malfunctioning of critical components, etc. Vibration can be controlled using passive, active and hybrid control systems. This paper presents the experimental studies carried out on the behaviour of impact dampers, which belong to the category of passive vibration control devices that are used to attenuate vibration of discrete and continuous systems. Impact damping is a technique for improving damping of a dynamic system by means of dissipation of energy due to collision of a free mass on the main mass.
 Experimental studies are carried out for forced vibration conditions by giving sinusoidal varying forcing function to the cantilever beam system using an exciter system and the time/frequency response function is determined. Impact mass is placed at free end of cantilever beam and the system is given constant base excitation and the damping of the system is studied by varying the frequency. Experiments are conducted for various mass ratios with different impact mass materials and the results are compared with theoretical predictions.

Fault-Tolerant Boundary Control of an Euler–Bernoulli Beam Subject to Output Constraint

In this article, the problem of the adaptive boundary control for Euler–Bernoulli beam systems is concerned, which contains actuator partial time-varying fault, external disturbances, and output constraint. Three control strategies are presented to study these problems. The first boundary controller is designed by constructing an adaptive law to compensate actuator partial time-varying fault. The second adaptive boundary controller is formulated to achieve disturbance rejection, in the case of actuator partial time-varying fault and unknown external disturbances, where a boundary disturbance observer is utilized to compensate the unknown boundary disturbance. The third adaptive boundary controller with a barrier term is proposed to constrain the boundary vibration. For all cases, the state of the beam system is guaranteed to be uniformly bounded. Finally, the simulation results illustrate the validity of the proposed control method.

Interfacial reaction behavior of titanium/steel composite plate formed by cold-hot rolling

Titanium/steel composite plate was prepared by cold-hot rolling method. The influence of temperature on the interfacial reaction behavior of titanium/steel composite plate was studied by double beam focused ion beam system and spherical aberration correction transmission electron microscopy. The results show that the interfacial reaction of the cold-rolled titanium/steel composite plate mainly occurs in the heating stage, and the continuous intermetallic compounds layer formed at the interface during heating fractures during hot rolling. An interfacial layer composed of submicron TiC layer and α-Ti/α-Fe is formed when the hot rolling temperature is not higher than 850 °C, and the interfacial bonding strength increases with the increase of rolling temperature. An interface layer composed of micro (FeTi+TiC)/Fe2Ti layer, nano FeTi/Fe2Ti layer and micro pores is formed when the hot rolling temperature exceeds 900 °C. The interfacial micro (FeTi+TiC)/Fe2Ti layer and micro pores will seriously damage the interfacial bonding quality.

Dynamic Simulation Analysis of Truck Crane Based on ADAMS

Background: With a reduction in the weight of telescopic boom crane and an increase in its lifting capacity, the contradiction between its speed, stability and safety becomes more prominent. The telescopic arm also has flexible deformation during operation, which will cause vibration of the whole vehicle system. Therefore, in order to ensure safety, accuracy, and efficiency in the working process, it is necessary to accurately predict the dynamic characteristics of the telescopic boom load in the working process. Objective: The purpose of this study is to establish a rigid-flexible coupling dynamic model of the crane, which can accurately reflect the dynamic characteristics of the telescopic boom during its operation in the simulation test. Methods: In theory, this study analyzes the characteristics of a truck crane and simplifies it as a cantilever beam. Based on the Euler-Bernoulli beam theory, the vibration differential equation of the mobile masscantilever beam system is established. In the aspect of simulation, the three-dimensional modeling software Solidworks is used to establish the solid model of the truck telescopic boom, the finite element analysis software is used to establish the finite element model of the telescopic boom, and the modal neutral file is generated and imported into ADAMS to establish the dynamic model of the truck crane multi-level flexible telescopic boom. The dynamic simulation of the virtual prototype model of the truck telescopic boom crane is carried out in ADAMS software to obtain the dynamic characteristics of the key components of crane under specific working conditions. Results: The vibration differential equation derived in theory can be used to solve the dynamic response of the crane jib under specific conditions by MATLAB programming. In the aspect of simulation, the error fluctuation and its causes in the key components of the crane in the working state are analyzed, and the rationality of the virtual prototype model is verified. Finally, through the trajectory planning of the crane under typical working conditions, the purpose of stable control of the telescopic boom system of the truck crane is realized. Conclusion: The derived equation is universal for solving the vibration of crane jib in general cases. The rigid-flexible coupling model also provides a reference for the dynamic modeling, analysis, design, and manufacture of a multi-stage flexible telescopic boom. The findings of this study can provide a reference for related patent research and development.

Effects of Kerr-type viscoelastic coupling layer with different stiffnesses on stochastic stability of Rayleigh double beams

This paper discusses the stochastic stability of a double Rayleigh beam system connected by a Kerr-type three-parameter elastic layer with two different stiffnesses, under compressive axial loads. The beams are modeled using the Rayleigh beam theory, and the axial forces consist of a constant component and a time-dependent stochastic function. The study investigates the almost-sure and moment stability of the double beam system subjected to stochastic compressive axial loading, utilizing the Lyapunov exponent and moment Lyapunov exponents. In the case of weak noise excitations, a singular perturbation method is employed to derive second-order expansions of the moment Lyapunov exponent and the Lyapunov exponent. Monte Carlo simulation is included to validate the obtained results. A numerical study is conducted for selected parameters, and the almost-sure and moment stability in the first and second perturbation are graphically presented. The results provide insights into the influences of different stiffnesses, damping, and the shear parameter of the Kerr-type layer on the stochastic stability of the coupled Rayleigh beam mechanical system, considering the effects of rotational inertia. It is quantitatively and qualitatively determined that reducing the stiffness of one part of the Kerr-type layer leads to a decrease in the stable region of stochastic stability, while reducing the shear parameter results in an increase in the stable region of stochastic stability. Furthermore, a quantitative relationship between different dampings of the Kerr-type viscoelastic layer is determined, where increasing either of the two damping parameters leads to an expansion of the stable region of stochastic stability. The inclusion of rotational inertia effects through the Rayleigh beam theory contributes to more accurate approximations of the obtained solutions.

Calibration method and performance of a time-of-flight detector to measure absolute beam energy in proton therapy.

The beam energy is one of the most significant parameters in particle therapy since it is directly correlated to the particles' penetration depth inside the patient. Nowadays, the range accuracy is guaranteed by offline routine quality control checks mainly performed with water phantoms, 2D detectors with PMMA wedges, or multi-layer ionization chambers. The latter feature low sensitivity, slow collection time, and response dependent on external parameters, which represent limiting factors for the quality controls of beams delivered with fast energy switching modalities, as foreseen in future treatments. In this context, a device based on solid-state detectors technology, able to perform a direct and absolute beam energy measurement, is proposed as a viable alternative for quality assurance measurements and beam commissioning, paving the way for online range monitoring and treatment verification. This work follows the proof of concept of an energy monitoring system for clinical proton beams, based on Ultra Fast Silicon Detectors (featuring tenths of ps time resolution in 50μm active thickness, and single particle detection capability) and time-of-flight techniques. An upgrade of such a system is presented here, together with the description of a dedicated self-calibration method, proving that this second prototype is able to assess the mean particles energy of a monoenergetic beam without any constraint on the beam temporal structure, neither any a priori knowledge of the beam energy for the calibration of the system. A new detector geometry, consisting of sensors segmented in strips, has been designed and implemented in order to enhance the statistics of coincident protons, thus improving the accuracy of the measured time differences. The prototype was tested on the cyclotron proton beam of the Trento Protontherapy Center (TPC). In addition, a dedicated self-calibration method, exploiting the measurement of monoenergetic beams crossing the two telescope sensors for different flight distances, was introduced to remove the systematic uncertainties independently from any external reference. The novel calibration strategy was applied to the experimental data collected at TPC (Trento) and CNAO (Pavia). Deviations between measured and reference beam energies in the order of a few hundreds of keV with a maximum uncertainty of 0.5 MeV were found, in compliance with the clinically required water range accuracy of 1mm. The presented version of the telescope system, minimally perturbative of the beam, relies on a few seconds of acquisition time to achieve the required clinical accuracy and therefore represents a feasible solution for beam commission, quality assurance checks, and online beam energy monitoring.

Replacement of Line Loads acting on slabs to equivalent uniformly Distributed Loads

This study aims to derive a general relation between line loads that acting on two-way slab system and the equivalent uniformly distributed loads. This relation will be so useful to structural designer that are used to working with a uniformly distributed load and enable them to use the traditional methods for analysis of two-way systems (e.g. Direct Design Method). Two types of slab systems, Slab System with Beams and Flat Slab Systems, have been considered in this study to include the effect of aspect ratio and type of slab on the proposed relation. Five aspect ratios, l2/l1 of 0.5, 0.75, 1.0, 1.5 and 2.0, have been considered for both types of two-way systems. All necessary finite element analyses have been executed with SAFE Software. Data obtained from the F. E. analyses have been used in a statistical analysis using Statistic Software to derive the relation based on a Linear Regression Analysis.

Investigation of nonlinear control of galloping with a linear beam with elastic boundary conditions

The aim of this study is nonlinear passive control of galloping oscillation on overhead transmission lines. The considered system is a linear beam subjected to harmonic and aerodynamic excitations which is coupled to a nonlinear absorber placed on an arbitrary position along the beam. Both extremities of the beam present rotationally and translationally elastic boundary conditions. After projection of spatio-temporal equations of the system on an arbitrary mode of the beam (the mode to be controlled), fast and slow system dynamics are traced which predict periodic or non periodic regimes. All analytical developments are compared with numerical results obtained from direct numerical integration of system equations and also from finite element modeling of the overall structure. Then, nonlinear passive control process of galloping instability by a non smooth nonlinear energy sink (NES) is investigated on a real case of galloping instability on a transmission line cable due to accretion of ice on it.

Preliminary Investigation on Steel Jacketing Retrofitting of Concrete Bridges Half-Joints

An innovative strengthening system for dapped-end beams is studied numerically and experimentally in this paper. The system is developed for the half-joint regions of bridge beams also commonly called “gerber saddles”, but it can be adapted to different scenarios. The strengthening system consists of two steel plates that are clamped on both sides of the webs of the beams by means of bolts. The purpose of the system is to transfer the highest possible amount of shear from the concrete webs to the steel plate elements reducing the resistance demand of the concrete half joint. Shear is transferred by friction from concrete to steel plates. The system is designed to be applied on existing bridges without heavy work interesting the carriageway, therefore reducing the interference with the traffic. Some interesting considerations emerge from the study, including the influence of the flange web connection on the structural behavior and the possible presence of brittle failure mechanisms that are difficult to model numerically using f.e.m. simulations.

Exact solutions of Euler–Bernoulli beams

In numerous real-world applications, transverse vibrations of beams are nonlinear in nature. It is a task to solve nonlinear beam systems due to their substantial dependence on the 4 variables of the system and the boundary conditions. To comprehend the nonlinear vibration characteristics, it is essential to do a precise parametric analysis. This research demonstrates an approximation solution for odd and even nonlinear transverse vibrating beams using the Laplace-based variation iteration method, and the formulation of the beams depends on the Galerkin approximation. For the solution of the nonlinear differential equation, this method is efficient as compared to the existing methods in the literature because the solutions exactly match with the numerical solutions. The Laplace-based variation iteration method has been used for the first time to obtain the solution to this important problem. To demonstrate the applicability and precision of the Laplace-based iteration method, several initial conditions are applied to the governing equation for nonlinearly vibrating transverse beams. The natural frequencies and periodic response curves are computed using Laplace-based VIM and compared with the Runge–Kutta RK4 method. In contrast to the RK4, the results demonstrate that the proposed method yields excellent consensus. The Lagrange multiplier is widely regarded as one of the most essential concepts in variational theory. The result obtained are displayed in the table form. Highlights The highlights of the solution of the Euler–Bernoulli beam equation with quintic nonlinearity using Lagrange multiplier are: 1. Introducing the constraint of the boundary conditions into the equation using Lagrange multipliers. 2. Formulating the equations for the Lagrange multipliers and the deflection of the beam. 3. Solving the resulting system of algebraic equations using numerical methods. 4. Obtaining the deflection of the beam as a function of its length and the applied load. 5. Analyzing the behavior of the beam under different loads and boundary conditions.

Optimal Control Strategy for Ship Cabin’s Active Chilled Beam System Using Improved Multi-Objective Salp Swarm Algorithm

Heating, ventilation, and air conditioning (HVAC) systems are the second largest energy consumers on cruise ships after the propulsion system. As a kind of HVAC system, active chilled beam (ACB) systems have been widely used for cabin service due to their performance of energy efficiency and good thermal comfort. However, conventional control strategies for ships’ ACB systems are not intelligent enough and cannot balance energy consumption and cabin comfort during the voyages of ships. This study developed an optimal control strategy for cabins’ ACB systems. First, a simulation environment considering dynamic conditions is established in TRNSYS. Second, an artificial neural network model is utilized to predict the energy consumption of the ACB system, while the predicted percentage dissatisfied is adopted to represent cabins’ thermal discomfort. Third, an improved multi-objective salp swarm algorithm is proposed to dynamically minimize both energy consumption and thermal discomfort. A TRNSYS–MATLAB co-simulation testbed is established to simulate the cabins served by an ACB system on a small cruise ship navigating from Hong Kong to Shanghai for validation tests and a comparison study. Compared to the conventional strategies, the proposed strategy can achieve a maximum energy savings of 12% while maintaining a predicted mean vote index less than 0.5, meeting the comfort requirements set by ASHRAE.