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Abstract While magnetomyography (MMG) using optically pumped magnetometers (OPMs) is a promising method for non-invasive investigation of the neuromuscular system, it has almost exclusively been performed in magnetically shielded rooms (MSRs) to date. MSRs provide extraordinary conditions for biomagnetic measurements but limit the widespread adoption of measurement methods due to high costs and extensive infrastructure. In this work, we address this issue by exploring the feasibility of mobile OPM-MMG in a setup of commercially available components. From field mapping and simulations, we find that the employed zero-field OPM can operate within a large region of the mobile shield, beyond which residual magnetic fields and perturbations become increasingly intolerable. Moreover, with digital filtering and moderate averaging a signal quality comparable to that in a heavily shielded MSR is attained. These findings facilitate practical and cost-effective implementations of OPM-MMG systems in clinical practice and research.

The aim of this work was to design, print, and examine elastic properties of porous structures with various parameters and beam distributions. These structures, generated using an algorithm, featured three types of lattices: octet, cubic, and Voronoi diagram-based, with different porosities (40%, 60%, 80%) and beam sizes (0.45mm, 0.66mm). They were printed using Direct Light Processing and examined using X-ray computed microtomography. Compression tests were conducted to determine the Young's modulus. The results were compared with computer simulations performed using Abaqus. The tools used, such as 3D printing and X-ray computed microtomography, were described, and the results and conclusions of the tests were presented. As a result, comparable outcomes were obtained for structures with higher beam diameter, while significantly different results were observed for structures with lower beam diameter. [ABSTRACT FROM AUTHOR]

The aim of this work was to design, print, and examine elastic properties of porous structures with various parameters and beam distributions. These structures, generated using an algorithm, featured three types of lattices: octet, cubic, and Voronoi diagram-based, with different porosities (40 %, 60 %, 80 %) and beam sizes (0.45 mm, 0.66 mm). They were printed using Direct Light Processing and examined using X-ray computed microtomography. Compression tests were conducted to determine the Young’s modulus. The results were compared with computer simulations performed using Abaqus. The tools used, such as 3D printing and X-ray computed microtomography, were described, and the results and conclusions of the tests were presented. As a result, comparable outcomes were obtained for structures with higher beam diameter, while significantly different results were observed for structures with lower beam diameter.

A new clamp-on power ultrasound solution is being developed for tubular heat exchangers (HX). This system features software-controlled ability to guide the cleaning effect, to reach also the most challenging locations. The new solution was evaluated by finite-element simulations, and field tests are being carried out on tubular HX. Preliminary results show that the new solution is capable of fouling prevention. The results suggest good potential also for fouling cleaning. In conclusion, the new software-guided clamp-on power ultrasound solution was proven valuable since it permits on-site fouling mitigation, without process interruptions, and by increasing the physical cleaning cycle of tubular HX. The solution will thus result in significant savings in equipment and maintenance costs as well as decreasing energy and production losses. [ABSTRACT FROM AUTHOR]

Electrochemical impedance spectroscopy (EIS) is becoming more and more relevant for the characterization of biosensors employing interdigitated electrodes. We compare four different sensor topologies for an exemplary use case of ion sensing to extract recommendations for the design optimizations of impedimetric biosensors. Therefore, we first extract how sensor design parameters affect the sensor capacitance using analytical calculations and finite element (FEM) simulations. Moreover, we develop equivalent circuit models for our sensor topologies and validate them using FEM simulations. As a result, the impedimetric sensor response is better understood, and sensitive and selective frequency ranges can be determined for a given sensor topology. From this, we extract design optimizations for different sensing principles. [ABSTRACT FROM AUTHOR]

Parametric Finite Element (FE) simulations were performed to investigate the ultimate flexural of different configurations of friction steel beam-to-column joints equipped with FREEDAM (free from damage) dampers. The main aim of this study was to compare the effectiveness of friction dampers featuring either single or multiple slotted holes, examining how these variations influence the behavior of the joint and the devices under seismic loads. In particular, the ultimate behavior of the connection (i.e., when the device reaches its maximum stroke) was investigated to characterize the involvement of the bolts in shear, the bearing of the plates, and the yielding of the supporting components. The analysis of bolt stress states revealed significant differences influenced by the number of bolts and slots. The FE models were calibrated against the experimental results obtained within the FREEDAM RFCS Project. These insights contribute to the design and performance evaluation of steel beam-to-column joints with FREEDAM connections, in particular the detailing of the haunch slots, laying the groundwork for future research and applications. [ABSTRACT FROM AUTHOR]

Heat transfer in fluids occurs in numerous industrial processes. It is a fact that diffusion coefficients during heat transfer in fluids do not remain constant. Therefore, consideration of the constant diffusion coefficient is not a good approximation. In view of this, generalized modelling of heat and mass transfer in fluids of variable properties is done, and these generalized problems are solved by finite element method (FEM). After pre- and post-calculations, numerical runs are executed to observe the influence of variation in conductance on transport mechanisms in the fluid. The impact of other parameters is also studied. The outcomes are recorded in the form of graphs and numerical data. Ohmic dissipation results in an increase in the temperature of the fluid for variable and constant viscosity. The thermal relaxation time has shown significant effects on the flow and thickness of the thermal boundary layer region. The temperature of the fluid decreases with thermal relaxation time. The thermal conductance of the fluid varies with an increase in temperature. Once the temperature rises, the ability of the fluid to conduct heat is increased, due to which more heat from the heated surface diffuses into the fluid. Hence, heat flux decreases.The behavior of the variable viscosity of the fluid on the diffusion of momentum into the fluid is studied, and it is now known that the diffusion of wall momentum into the fluid is compromised because of a decrease in the viscosity, which is inversely proportional to the temperature. Hence, the diffusion of wall momentum into the fluid in the isothermal case is greater than that in the temperature-varying case.

Electrochemical impedance spectroscopy (EIS) is becoming more and more relevant for the characterization of biosensors employing interdigitated electrodes. We compare four different sensor topologies for an exemplary use case of ion sensing to extract recommendations for the design optimizations of impedimetric biosensors. Therefore, we first extract how sensor design parameters affect the sensor capacitance using analytical calculations and finite element (FEM) simulations. Moreover, we develop equivalent circuit models for our sensor topologies and validate them using FEM simulations. As a result, the impedimetric sensor response is better understood, and sensitive and selective frequency ranges can be determined for a given sensor topology. From this, we extract design optimizations for different sensing principles.

This paper presents a numerical investigation regarding the possibility of using electrically conductive concrete (ECON) combined with concrete-encased electrode (CEE) technology to develop new substation grounding systems (SGSs) called ECON-EE as a replacement for conventional copper or galvanized steel grounding grids. In the first step, the validation of the commercial FEM software used to perform grounding system analysis was performed in terms of the grid resistance (RG), ground potential rise (GPR), and step and touch voltages, using a symmetrical 70 m × 70 m conventional copper SGS. Next, several numerical simulations of an ECON-EE grounding system with the same dimensions as the conventional copper grid used for FEM software validation were performed. Thus, several parameters of the ECON-EE grounding system were studied, such as the geometry, dimensions, and resistivity of ECON and the diameter of the rebar. The numerical results obtained permit us to demonstrate that ECON-EE grounding systems can perform better than conventional SGSs equipped with vertical rods, particularly in the case of high ground resistivity. Moreover, it was demonstrated that the two main ECON-EE parameters affecting the grounding resistance and the touch and step voltages are the section area and the resistivity of the ECON. As discussed in detail in this paper, the proposed ECON-EE grounding system can offer several advantages compared to conventional SGSs in terms of efficiency and durability, as well as in terms of simplicity of conception and implementation. [ABSTRACT FROM AUTHOR]

Parametric Finite Element (FE) simulations were performed to investigate the ultimate flexural of different configurations of friction steel beam-to-column joints equipped with FREEDAM (free from damage) dampers. The main aim of this study was to compare the effectiveness of friction dampers featuring either single or multiple slotted holes, examining how these variations influence the behavior of the joint and the devices under seismic loads. In particular, the ultimate behavior of the connection (i.e., when the device reaches its maximum stroke) was investigated to characterize the involvement of the bolts in shear, the bearing of the plates, and the yielding of the supporting components. The analysis of bolt stress states revealed significant differences influenced by the number of bolts and slots. The FE models were calibrated against the experimental results obtained within the FREEDAM RFCS Project. These insights contribute to the design and performance evaluation of steel beam-to-column joints with FREEDAM connections, in particular the detailing of the haunch slots, laying the groundwork for future research and applications.

The article presents precision and numerically stable method of calculation of the characteristic impedance of cylindrical multilayer waveguides used in high-precision wideband measuring instruments and standards, especially calculable thermal converters of AC voltage and precision wideband current shunts. Most of currently existing algorithms of characteristic impedance calculation of such waveguides are based upon approximations. Unfortunately, application of such methods is limited to waveguides composed of a specific, usually low number of layers. The accuracy of approximation methods as well as the number of layers is sometimes not sufficient, especially when the coaxial waveguide is a part of precision measurement equipment. The article presents the numerically stable matrix analytical formula using exponentially scaled modified Bessel functions to compute characteristic impedance and its components of the cylindrical coaxial multilayer waveguides. Results obtained with the developed method were compared with results of simulations made using the Finite Element Method (FEM) software simulations. Very good agreement between results of those two methods were achieved.

Transversely loaded beam grillages are quite often used in industrial construction. In order to produce a safe design of such structures, it is necessary to account for the lateral torsional buckling phenomenon, which reduces load-bearing capacity. To be able to calculate the relevant reduction factor, the elastic critical load must be determined. As regards the existing design practice for such structures, simplified conditions are assumed for the mutual restraint of the component beams. However, this approach does not correspond to reality. This study discusses the results of numerical investigations and analytical calculations concerning the effect of the elastic action of simple beam grillage (SBG) joints on the critical load, which results from the lateral torsional buckling (LTB) condition. The SBG was defined as a flat system of interconnected beams, unstiffened laterally and loaded perpendicularly to the grillage plane. The analysis covered H-shaped grillages with different span ratios of component beams, in which the main (coupling) beam was decisive for instability. The effectiveness of the use of closed-section stiffeners at the grillage joints was also investigated. The grillage elastic critical resistances (ECR) were determined for two variants of joint stiffening. The computations were performed by means of FEM numerical simulations. The spatial models were discretised with the following elements: (1) solid ones in Abaqus, (2) shell ones in ConSteel, and (3) thin-walled bars in ConSteel. The LTB critical moments of the weakest beam (critical beam), elastically restrained against warping and against lateral rotation (in the LTB plane), were computed using the analytical methods developed by the authors. To this end, the methods were proposed to determine the indexes of the critical beam elastic restraint in the adjacent stiffening beams. In the study, it was demonstrated that (1) taking into account the conditions of mutual elastic restraint and interaction of the component beams provides a more accurate assessment of the grillage ECR, (2) the use of closed-section stiffeners in the grillage joints increase the ECR compared with classic flat stiffeners, (3) the grillage ECR can be estimated based on the critical moment Mcr of the weakest beam (critical beam) when the conditions of its elastic restraint in joints are accounted for. [ABSTRACT FROM AUTHOR]

Good light trapping is essential to make high efficiency InGaN-based solar cells. As InGaN wafers are being made increasingly, thinner, light trapping becomes even more important. In this study, we propose a structure of one-dimensional InGaN grating for the InGaN-based solar cells is proposed. The solar energy absorption characteristics of this structure are studied by the the Finite element method (FEM) method. By alternately altering the grating depth and the filling factor, a new type of grating structure is proposed. For such a structure, different gratings are studied. Numerical computation shows that the absorptance of the InGaN grating structure is over 0.88 throughout the entire computational band. The optimum parameters of the proposed structure are period (a = 480 nm), a filling factor (ff = 50 %) and depth (d=210 nm), which indicates the proposed structured surface may have potential applications in solar cells manufacturing. [ABSTRACT FROM AUTHOR]

This elaboration presents the concept of the design, parameters, experimental investigation, and thermal numerical model solved using the finite element method of a high-power-density DC–DC converter. The analyzed unit can be utilized as a stand-alone converter or as a module for a scalable high-voltage gain system. The converter has a decreased bill of materials since it does not use typical chokes and heatsinks. It is based on switched capacitor circuits supported by a resonant choke which protects against inrush currents. A printed circuit board is utilized not only for the resonant inductance design but also for cooling transistor and diode devices. The paper demonstrates the design concept and the achieved parameters. Experimental results show heat distribution on the printed circuit board and components in a steady state and dynamical states as well. The converter parameters and their efficiency are measured as well. The convergence of experimental results and heating simulations is demonstrated. The numerical model is used for the investigation of design cases. The printed circuit board size, thermal via pattern, and heating process during the overload of the converter are investigated. [ABSTRACT FROM AUTHOR]

We present a detailed investigation of the near-field optical response of core-shell nanoparticles using Fourier-demodulated full-wave simulations, revealing significant modifications to established contrast mechanisms in infrared scattering-type scanning near-field optical microscopy (s-SNOM). Our work examined the complex interplay of geometrical and optical resonances within core-shell structures. Using a finite element method (FEM) simulation closely aligned with the actual s-SNOM measurement processes, we capture the specific near-field responses in these nanostructures. Our findings show that core-shell nanoparticles exhibit unexpected distinct resonance shifts and massively enhanced scattering driven by both the core and shell properties. This investigation not only advances the understanding of near-field interactions in complex nanosystems but also provides a refined theoretical framework to accurately predict the optical signatures of nanostructures with internal heterogeneity.

Vertical Hall sensors (VHSs), compatible with complementary metal oxide semiconductor (CMOS) technology, are used to detect magnetic fields in the plane of the sensor. In previous studies, their performance was limited by a large offset. This paper reports on a novel CMOS seven-contact VHS (7CVHS), which is formed by adding two additional contacts to a traditional five-contact VHS (5CVHS) to alleviate the offset. The offset voltage and offset magnetic field of the 7CVHS are reduced by 90.20% and 88.31% of those of the 5CVHS, respectively, with a 16.16% current-related sensitivity loss. Moreover, the size and positions of the contacts are optimized in standard GLOBALFOUNDRIES 0.18 μm BCDliteTM technology by scanning parameters using FEM simulations. The simulation data are analyzed in groups to study the influence of the size and contact positions on the current-related sensitivity, offset voltage, and offset magnetic field. [ABSTRACT FROM AUTHOR]

This paper presents a numerical investigation regarding the possibility of using electrically conductive concrete (ECON) combined with concrete-encased electrode (CEE) technology to develop new substation grounding systems (SGSs) called ECON-EE as a replacement for conventional copper or galvanized steel grounding grids. In the first step, the validation of the commercial FEM software used to perform grounding system analysis was performed in terms of the grid resistance (RG), ground potential rise (GPR), and step and touch voltages, using a symmetrical 70 m × 70 m conventional copper SGS. Next, several numerical simulations of an ECON-EE grounding system with the same dimensions as the conventional copper grid used for FEM software validation were performed. Thus, several parameters of the ECON-EE grounding system were studied, such as the geometry, dimensions, and resistivity of ECON and the diameter of the rebar. The numerical results obtained permit us to demonstrate that ECON-EE grounding systems can perform better than conventional SGSs equipped with vertical rods, particularly in the case of high ground resistivity. Moreover, it was demonstrated that the two main ECON-EE parameters affecting the grounding resistance and the touch and step voltages are the section area and the resistivity of the ECON. As discussed in detail in this paper, the proposed ECON-EE grounding system can offer several advantages compared to conventional SGSs in terms of efficiency and durability, as well as in terms of simplicity of conception and implementation.

Perovskite solar cells (PSCs) show great potential for efficient solar energy conversion, but their long-term stability is still a concern. To address this issue, we developed a vacuum-deposited bismuth-based perovskite-like material (Cs 3 Bi 2 I 9), which forms a high-quality thin film showing remarkable stability over 150 days of air exposure. When combined with a solution-processed MAPbI 3 perovskite, the resulting device exhibits improved stability under varying environmental conditions. However, the power conversion efficiency (PCE) drops by 70% compared to the reference MAPbI 3 -based PSC. An advanced multiphysics optoelectrical device simulation combining 3D FDTD and FEM methods validates these findings, yielding results in excellent agreement with the experimental data. The study also provides insight into the device's optics and electronic properties, revealing the factors that limit its performance. An optimized device design is proposed to reach an 18.81% PCE, higher than the reference device. The findings have significant implications for developing next-generation solar cells, including high-performance tandem solar cells. [Display omitted] Vacuum deposited Cs 3 Bi 2 I 9 single junction PSCs exhibited almost no degradation even under ambient conditions after 150 days. MAPbI 3 /Cs 3 Bi 2 I 9 device retained ~95% of its initial PCE even after 280 mins of continuous light illumination (1-sun) in air. Resultant device used a thin Cs 3 Bi 2 I 9 cover layer, facilitating great improvement in the device stability. The use of 3D Multiphysics (FDTD & FEM) Simulations enables detailed optoelectronic modeling of device performance. Propose a Cs 3 Bi 2 I 9 /MAPbI 3 -based device estimates a PCE of 18.81%. [ABSTRACT FROM AUTHOR]

This paper presents an optimization scheme to better design phononic crystals. A locally resonant phononic crystal (LRPC) structure called square spiral with circle inside is employed to verify the performance of the present scheme. Four geometric parameters, i.e., the side length of square scatterer, the length of each elastic beam, the thickness of elastic beams, and the radii of inner circles, are considered to obtain the corresponding influences on band gaps (BGs) using finite element method (FEM). According to the significant influences of the late two key parameters, a 2-factor (the radii of inner circles, and the thickness of elastic beams) and 7-level experiment is designed to obtain optimal BGs with better low-frequency broadband properties. By 29 times calculations using FEM for the different combination of levels, three relationships between the 2-factor and the first BG's starting frequency, the first BG's bandwidth, and the second BG's bandwidth, are obtained and severed as inputs to the software of response surface methodology (RSM). The closed-form expressions of the three relationships are finally obtained to construct optimization models and result in the optimal band gaps (BGs) between 190-300Hz and 500-600Hz. It is expected that the present optimization scheme can be extended to material design of phononic/photonic structures in a reasonable way.

Vertical Hall sensors (VHSs), compatible with complementary metal oxide semiconductor (CMOS) technology, are used to detect magnetic fields in the plane of the sensor. In previous studies, their performance was limited by a large offset. This paper reports on a novel CMOS seven-contact VHS (7CVHS), which is formed by adding two additional contacts to a traditional five-contact VHS (5CVHS) to alleviate the offset. The offset voltage and offset magnetic field of the 7CVHS are reduced by 90.20% and 88.31% of those of the 5CVHS, respectively, with a 16.16% current-related sensitivity loss. Moreover, the size and positions of the contacts are optimized in standard GLOBALFOUNDRIES 0.18 μm BCDliteTM technology by scanning parameters using FEM simulations. The simulation data are analyzed in groups to study the influence of the size and contact positions on the current-related sensitivity, offset voltage, and offset magnetic field.

High-intensity focused ultrasound (HIFU) has been used in different medical applications in the last years. In this work, we present for the first time the use of HIFU in the field of cryopreservation, the preservation of biological material at low temperatures. An HIFU system has been designed with the objective of achieving a fast and uniform rewarming in organs, key to overcome the critical problem of devitrification. The finite-element simulations have been carried out using COMSOL Multiphysics software. An array of 26 ultrasonic transducers was simulated, achieving an HIFU focal area in the order of magnitude of a model organ (ovary). A parametric study of the warming rate and temperature gradients, as a function of the frequency and power of ultrasonic waves, was performed. An optimal value for these parameters was found. The results validate the appropriateness of the technique, which is of utmost importance for the future creation of cryopreserved organ banks. [ABSTRACT FROM AUTHOR]

This study presents an analytical model of a flextensional actuator comprised of a piezoceramic rod or stack transducer integrated into a flexible mechanical structure. It converts and amplifies the longitudinal in-plane strains in the transducer into the out-of-plane bending of metal beams. Two curvilinear beams mounted by means of two hinged links with an offset to a centrally located piezoceramic transducer create a monolithic hinge lever mechanism. The idea behind that solution is to reduce the bending stiffness at the hinges, while maintaining enough axial rigidity of the active beams and obtain greater magnification of the out-of-plane displacement. As the main purpose of this work is to estimate the influence of piezoelectric force on the performance of flextensional actuators of different geometric shapes and mechanical parameters, two transducers have been considered. An analytical model of the actuator has been developed on the basis of the stationary value of the total potential energy principle with the use of the von Karman non-linear strains theory. Moreover, the application of structure prestressing is considered to avoid undesired stretching of the piezoceramic transducer. A vast number of results exhibit the mechanical responses of the actuator of different geometry, initial midspan rise and beam material properties to piezoelectric stimulation. The analytical method described here may be adopted for other types of flextensional actuators. Additionally, a numerical model of flexure-guided transducer is presented to show that the analytical solution can provide a set of valuable design parameters in less time than FEM simulations. Models of two configurations of flextensional actuator are analytically developed Static behavior of the structure under the electric field is examined Prestressing of the actuator is considered to prevent undesired stretching Analytical solution is verified with the results from FEM [ABSTRACT FROM AUTHOR]

In this paper, a new portable, low-cost magnet with a good homogeneity is presented. The single-layer central magnet structure based on Halbach-type array has been designed, simulated which can generate a magnetic field of 1 T under the weight of 2 kg. Magnetic strips placed at the ends of the central magnet are presented to improve the central homogeneity. In order to counteract the inhomogeneity resulting from manufacturing tolerances, a new compact shimming structure designed for miniature Halbach magnet is applied. With this structure a reduction of the full width at half maximum (FWHM) from 21 kHz to less than only 0.7 kHz, which is adequate for achieving a good NMR relaxation signal. This novel miniature magnet structure has achieved an excellent balance between cost and homogeneity for portable time domain NMR. [ABSTRACT FROM AUTHOR]

In tomoelastography, to achieve a final wave speed map by combining reconstructions obtained from all spatial directions and excitation frequencies, the use of weights is inevitable. Here, a new weighting scheme, which maximizes the signal‐to‐noise ratio (SNR) of the final wave speed map, has been proposed. To maximize the SNR of the final wave speed map, the use of squares of estimated SNR values of reconstructed individual maps has been proposed. Therefore, derivations of the SNR of the reconstructed wave speed maps have become necessary. Considering the noise on the complex MRI signal, the SNR of the reconstructed wave speed map was formulated by an analytical approach assuming a high SNR, and the results were verified using Monte Carlo simulations (MCSs). It has been assumed that the noise remains approximately Gaussian when the image SNR is high enough, despite the nonlinear operations in tomoelastography inversion. Hence, the SNR threshold was determined by comparing the SNR computed by MCSs and analytical approximations. The weighting scheme was evaluated for accuracy, spatial resolution and SNR performances on simulated phantoms. MR elastography (MRE) experiments on two different phantoms were conducted. Wave speed maps were generated for simulated 3D human abdomen MRE data and experimental human abdomen MRE data. The simulation results demonstrated that the SNR‐weighted inversion improved the SNR performance of the wave speed map by a factor of two compared to the performance of the original (i.e., amplitude‐weighted) reconstruction. In the case of a low SNR, no bias occurred in the wave speed map when SNR weighting was used, whereas 10% bias occurred when the original weighting (i.e., amplitude weighting) was used. Thus, while not altering the accuracy or spatial resolution of the wave speed map with the proposed weighting method, the SNR of the wave speed map has been significantly improved. [ABSTRACT FROM AUTHOR]

Abstract Dike propagation is an intrinsically multiphase problem, where deformation and fluid flow are intricately coupled in a fracture process. Here we perform the first fully coupled simulations of dike propagation in two dimensions, accounting for depressurization of a circular magma chamber, dynamic fluid flow, fracture formation, and elastic deformation. Despite the complexity of the governing equations, we observe that the lengthening is well explained by a simple model a(t)=c1log(1+t/c2), where a is the dike length, t is time, and c1 and c2 are constants. We compare the model to seismic data from eight dikes in Iceland and Ethiopia, and, in spite of the assumption of plane strain, we find good agreement between the data and the model. In addition, we derive an approximate model for the depressurization of the chamber with the dike length. These models may help forecast the growth of lateral dikes and magma chamber depressurization.

The article describes the result of theoretical research aimed at assessing the loads and operating conditions of a Coiled Tubing pipeline injecting water, suspended to the mining platform of Lotos Petrobaltic. For this purpose, appropriate calculation models have been developed using the Finite Element Method (FEM), taking into account the nature of the analyzed object and its loads. The analyzes were carried out for two pipes (previously operated and newly proposed) differing in geometrical and strength parameters. The research was carried out for selected directions of load on the pipeline (originating from sea waves) and various variants of attaching the suspended pipeline to the mining platform.

The article presents the analysis, project, and experimental examination of an original rigid riser for Coil Tubing Pipes. The principle of riser operation is based on the use of friction forces. The research included the FEM analysis of the designed riser, calculations of the required bolt tensions, and checking the effect of the clamping force on stress distribution in the pipeline. The results of computer simulation were verified on a specially designed test rig. The described riser design was implemented on the LOTOS Petrobaltic platform, thus eliminating the need for purchase and installation of expensive elastic risers.

This paper explores the fundamental steps towards the development of a 6-axis piezoelectric Inertial Measurement Unit (IMU). The main specification of the reported device is its ability to concurrently detect 3-axis acceleration and angular velocity using a single mass-based design. This work represents a detailed numerical analysis based on a finite element model. Experimental reported data are exploited to validate the FEM model in terms of acceleration detection which is ensured through the direct piezoelectric effect. The angular rate is detected thanks to the Coriolis effect by ensuring drive and sense modes. Using a Finite Element Analysis (FEA), light was shed on the different basic parameters that influence the sensor performance in order to present an optimized design. A detailed geometrical investigation of factors such as anchor position, optimized locations for sensing electrodes, proof-mass dimensions, PZT thickness, and operating frequency is illustrated. The 6-DOF sensor outputs are extracted in terms of the original and the optimized design. The amelioration rate of sensitivity is found to be up to 165% for linear acceleration, while for angular rate sensing, the lateral sensitivity is ameliorated by about 330% and is multiplied by around ten times in the normal axis. The optimized design exhibits a good acceleration sensitivity of 260mV/g in the lateral axis and 60.7mV/g in the z-axis. For angular rate sensing, the new design is more sensitive along the longitudinal axis than the lateral one. Sensitivity values are found to be 2.65µV/rad/s for both x-and y-axis, and 1.24V/rad/s for the z-axis. [ABSTRACT FROM AUTHOR]

The article deals with a FEM analysis of main parts of an engineering design of a pneumatically controlled manipulator, which will serve for mounting a compressor to a PO536 car chassis. This car chassis belongs to SUV cars and it is equipped with a pneumatic suspension system. It is the chassis of a Porsche Cayenne car produced in the Slovak Republic. The designed manipulator will be located on the assembly line of this vehicle. Except of FEM analyses of designed important parts of the manipulator, which are necessary for verification of safety of the design in order to obtain distribution of stresses and deformations in a structure, the it contains also the design of a pneumatic circuit of the manipulator together with pneumatic logic and it individual components. Based on three-dimensional model, there will be possible to generate drawings of the manipulator for manufacturing of the device and its application to the real operation. [ABSTRACT FROM AUTHOR]

Photocatalysis is an effective way to utilize solar energy to produce hydrogen from water. Au/TiO 2 nanoparticles (NPs) have a better performance in photocatalytic hydrogen generation because of the localized surface plasmon resonance (LSPR) effect of Au/TiO 2 NPs. In the photocatalytic hydrogen generation experiments, it was found that light intensity plays a key role in the photocatalytic reaction rate of Au/TiO 2 NPs. At a light intensity of 0–7 kW/m2, the reaction rate has a super-linear law dependence on the light intensity (Rate ∝ Intensity n , with n > 1). However, at a light intensity of 7–9 kW/m2, the dependency becomes sub-linear (n < 1). This means that the increase rate of photocatalytic rate is smaller than that of light intensity when the light intensity exceeds 7 kW/m2. In addition, the finite element method (FEM) was utilized to further elucidate the role of light intensity by calculating the absorption power and nearfield intensity mapping of a Au/TiO 2 nanoparticle. The variation trend of the calculated total absorption power agrees with the photocatalytic experimental results for different light intensities. These results shed light on the utilization of concentrated solar photocatalysis to increase the solar-to-hydrogen performance of Au/TiO 2 NPs. Image 1 • Photocatalytic hydrogen generation experiments are designed at light intensities of 0–9 kW/m2. • Light intensity plays an essential role in photocatalysis of Au/TiO 2 nanoparticles because of LSPR effect. • An FEM model of the Au/TiO 2 nanoparticle at different light intensities is established. • The relationship between photocatalytic hydrogen generation rate and light intensity is given. [ABSTRACT FROM AUTHOR]

Dike propagation is an intrinsically multiphase problem, where deformation and fluid flow are intricately coupled in a fracture process. Here we perform the first fully coupled simulations of dike propagation in two dimensions, accounting for depressurization of a circular magma chamber, dynamic fluid flow, fracture formation, and elastic deformation. Despite the complexity of the governing equations, we observe that the lengthening is well explained by a simple model a(t)=c1log(1+t/c2), where a is the dike length, t is time, and c1 and c2 are constants. We compare the model to seismic data from eight dikes in Iceland and Ethiopia, and, in spite of the assumption of plane strain, we find good agreement between the data and the model. In addition, we derive an approximate model for the depressurization of the chamber with the dike length. These models may help forecast the growth of lateral dikes and magma chamber depressurization. Plain Language Summary: Volcanic dike intrusions, propagating magma‐filled fractures, precede most eruptions. Dike propagation has been studied for decades through simplified analytical and numerical models. To date, no study has fully addressed how the fluid magma, host rock, and the magma chamber all interact at the same time and drive the dike forward. We present such simulations for a two‐dimensional configuration and deduce that a simple formula can explain how the dike lengthens with time. We suggest that this simple formula may be used to forecast dike growth. Key Points: Fully coupled simulations of dike growth and magma chamber depressurization are performedA simple model for dike length with time is identified and compared to seismic observationsA simple model of chamber pressure versus dike length is derived and compared to simulations [ABSTRACT FROM AUTHOR]

Spray-dried refractory carbide and metal powder mixtures, containing tungsten carbide, is compacted and sintered during the production of conventional cutting tool inserts. Since friction between the pressing tool and the powder gives rise to density gradients in the powder compact, shrinkage during sintering is uneven. The shape of the sintered blank is important and can be predicted with finite element (FE) simulations. To validate the simulation of the pressing procedure, the density gradients in the powder compacts must be measured with a high spatial resolution. Since tungsten has a high atomic number, it is hard to penetrate with X-rays and even cold neutrons. We show here that by using a polychromatic beam of thermal neutrons, along with beam-hardening correction, such measurements can be successfully realized. The obtained results show good agreement with corresponding FE-simulations. Also, deliberate differences in the compaction process could be verified with the neutron measurements. Unlabelled Image • For the first time, density distributions in cemented carbide compacts are measured. • Good agreement is found between measurements and FEM-simulations. • Process characteristics related to rate-dependence and creep are determined. [ABSTRACT FROM AUTHOR]

Corona is a critical effect that must be considered during the design and optimisation stages of high‐voltage hardware such as substation connectors, since due to the harmful effects, corona threats power systems reliability. Visual corona tests allow detecting and identifying the critical corona points on the surface of substation connectors, so corrective actions can be applied for product optimisation. This article focuses on reduced‐scale (RS) visual corona tests intended to verify and optimise the behaviour of such high‐voltage hardware. RS visual corona tests allow reducing the voltage to be applied, laboratory size, instrumentation requirements, assembly, and test times, and finally the overall costs of the tests compared to standard corona tests carried out in large‐size high‐voltage laboratories. A hybrid approach combining experimental tests and finite element method (FEM) simulations is presented, which allows obtaining the equivalent visual corona onset voltage between RS and full‐scale tests. Although the article focuses on the analysis of aluminium substation connectors, the proposed approach can be applied to many other hardware intended for high‐voltage applications. [ABSTRACT FROM AUTHOR]

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Fretting wear resulting from micro-displacement oscillatory movements is considered a serious impediment to many industrial applications like gears, turbo engines, etc. Large conformal contact configurations of industrial components are very complicated to reproduce at laboratory scale. As a result, simple non-conformal contact geometries including sphere-on-flat and cylinder-on-flat are usually adopted in research laboratories. Yet, few are the researches that examined fretting wear using flat-on-flat geometry due to its high sensitivity to alignment issues although this contact configuration allows the analysis of quasi-constant pressure condition. In the current study, fretting wear of flat-on-flat dry contact made of a steel alloy (35NCD16) is investigated experimentally by varying several parameters including test duration, contact pressure, sliding amplitude and frequency. A power law formulation is introduced providing reliable prediction of the wear rate. The analysis of test results confirms a high dependency of the wear kinetics on the loading condition regarding the transition from abrasive to adhesive wear. • Flat-on-flat contact for a dry 35NCD16 interface is studied at ambient temperature. • FEM simulations showed an iso-pressure condition at the interface except the edges. • Wear kinetics highly depends on the loading conditions: N, p, δ g and f. • A wear volume prediction model is proposed incorporating all the loading conditions. • Experimental and predicted wear volumes were highly correlated. [ABSTRACT FROM AUTHOR]

Tip-enhanced Raman spectroscopy (TERS) has experienced tremendous progress over the last two decades. Despite detecting single molecules and achieving sub-nanometer spatial resolution, attaining high TERS sensitivity is still a challenging task due to low reproducibility of tip fabrication, especially regarding very sharp tip apices. Here, we present an approach for achieving strong TERS sensitivity via a systematic study of the near-field enhancement properties in the so-called gap-mode TERS configurations using the combination of finite element method (FEM) simulations and TERS experiments. In the simulation study, a gold tip apex is fixed at 80 nm of diameter, and the substrate consists of 20 nm high gold nanodiscs with diameter varying from 5 nm to 120 nm placed on a flat extended gold substrate. The local electric field distributions are computed in the spectral range from 500 nm to 800 nm with the tip placed both at the center and the edge of the gold nanostructure. The model is then compared with the typical gap-mode TERS configuration, in which a tip of varying diameter from 2 nm to 160 nm is placed in the proximity of a gold thin film. Our simulations show that the tip-nanodisc combined system provides much improved TERS sensitivity compared to the conventional gap-mode TERS configuration. We find that for the same tip diameter, the spatial resolution achieved in the tip-nanodisc model is much better than that observed in the conventional gap-mode TERS, which requires a very sharp metal tip to achieve the same spatial resolution on an extended metal substrate. Finally, TERS experiments are conducted on gold nanodisc arrays using home-built gold tips to validate our simulation results. Our simulations provide a guide for designing and realization of both high-spatial resolution and strong TERS intensity in future TERS experiments.

The paper reports a selection of numerical and experimental results of a new closed-die forging method for producing AZ31 magnesium alloy aircraft brackets with one rib. The numerical modelling of the new forming process was performed by the finite element method.The distributions of stresses, strains, temperature and forces were examined. The numerical results confirmed that the forgings produced by the new forming method are correct. For this reason, the new forming process was verified experimentally. The experimental results showed good agreement with the numerical results. The produced forgings of AZ31 magnesium alloy aircraft brackets with one rib were then subjected to qualitative tests.

Microstructure evolution during the hot forming shows a significant impact on material’s mechanical properties. To explore the deformation characteristics of 5CrNiMoV steel, numerical simulation and microscopic phase-field simulation of the multi-direction forgings were carried out. The strain distribution at each pass was investigated and the evolution of temperature, effective strain, effective strain rate, and grain size was acquired. The hot forging trials were carried out and three typical regions of forgings were taken to study the microstructure evolution. Detailed microstructure characterizations showed that the constructed parent austenite grain size of the forging in typical regions was slightly larger than the simulation results due to the grain coarsening during the air cooling. There were large amounts of high angle grain boundaries (HAGBs) for the occurrence of complete dynamic recrystallization and many bulging grain boundaries showed that discontinuous dynamic recrystallization (DDRX) could be the governing mechanism of nucleation and growth of dynamic recrystallization (DRX). Besides, the hot deformation texture changed significantly during the non-isothermal forging and the texture component differed remarkably at different regions of the forging. The main hot deformation texture components were Cube {001} and Goss{011}.

Due to interest in lenses at telecommunicatons in the lower frequency range of 30–600 GHz (5G/6G applications) sub‐terahertz range lenses have started to make their appearance. Geometrical optics is typically used due to its faster calculation speed, which is faster than finite element methods (FEMs). A 30‐mm plano‐convex lens was simulated with a COMSOL ray tracing module and CST was used to simulate 30, 60, 300 and 600 GHz FEM simulations. Focal points were 248, 189, 180, 118 and 131 mm with CST and 253 mm with COMSOL. [ABSTRACT FROM AUTHOR]

Sensors sensitivity, selectivity and stability has always been a prime design concern for gas sensors designers. Modeling and simulation of gas sensors aids the designers in improving their performance. In this paper, different routes for the modeling and simulation of a semiconducting gas sensor is presented. Subsequently, by employing one of the route, the response of Zinc Oxide nanowire transistor towards nitrogen dioxide ambient is simulated. In addition to the sensing mechanism, simulation study of gas species desorption by applying a recovery voltage is also presented.

Extrusion tools, such as containers and stems, are expensive components, and it is important to use the most suitable materials to gain a long service life. It has to be pointed out, however, that not only the applied materials determine the life time of these tools, but also melting and forging techniques as well as heat treatment have an essential impact.For many years, Bohler Special Steel Open Die Forge has been a supplier of forged high-quality components for the extrusion industry, e. g. mantels, liner, liner holder, stems, and accessories for containers.This paper reports on the experiences and research activities in the fabrication of forged components for containers and stems for the extrusion industry and covers material selection up to achieved mechanical properties and ultrasonic test results. Moreover, heating and Finite Element Method (FEM) modelling of stress distributions in the container during the extrusion process in order to optimize and predict the lifetime of these components are discussed. From the material side, the focus is set on the classical 5% chromium steel class, up to the high-alloyed and sophisticated Maraging steels for stem application, mainly in indirect extrusion processes, with the highest compressive stresses required. [ABSTRACT FROM AUTHOR]