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Introduction: This paper reviews the analytical method of assessing the seismic and extreme load resistance of buildings with a complex macrostructure that includes elastic-plastic inserts operating in shear. Methods: We analyze a number of studies that rationalize the choice of models for simulating complex elastic-plastic deformation in a mechanical system with several degrees of freedom, as well as studies that review the durability and resilience of buildings with a complex macrostructure based on non-linear shear links when subjected to dynamic and extreme impact. We also consider the methods of structural analysis regarding buildings with elastic-plastic inserts, accounting for the plastic hinged joints of metal frames. Results: We apply the analytical method to linear and non-linear systems with n degrees of freedom. We propose a mathematical equation that describes the nature of shear link response to seismic and extreme loads. Our method makes it possible to obtain an analytical solution for structures with proportionate and disproportionate damping by using the direct integration algorithm. Discussion: Most structures with a broad range of construction material properties require a disproportionate damping model. In this study, we solve equations by using the direct integration algorithm based on disproportionate damping. Under high dynamic load, the reinforcement of shear inserts operates in a plastic state.

The development of advanced, human like tactile sensing capabilities is one of the key challenges for next generation robots or prosthetics. Tactile sensors arrays will need to exhibit the desired sensing capabilities, show robustness to external influences as well as good approaches for the integration of large amounts of sensors. We present a tactile sensor array technology, based on the fabrication of a flexible interconnection substrate containing directly integrated tactile sensors. This approach has several advantages: interconnection substrate technology is widely available making upscaling of sensor arrays easy to a large amount of sensors and/or large sensing areas, the direct integration of sensors allows for a simple and very compact approach to densely packed sensor arrays and the structured flexible substrate enables integration into complex, three-dimensional bodies. We present sensors with a size of 600 μm and arrays of up to 12 x 12 individually addressable sensors. The sensors have a wide measurement range; free membrane deformation results in a high sensitivity of 2.6 kPa⁻¹ respectively 2600 N⁻¹ for small applied pressures (0-0.6 kPa) whereas deforming polymer studs extend the measurement range for larger applied pressures (5-25 kPa) with a sensitivity of 0.022 kPa⁻¹ respectively 22 N⁻¹. A statistical study of six sensor arrays from three wafers showed repeatable performance of the fabricated structures and robustness tests proved the stable sensing conditions over 10'000 cycles., Journal of Microelectromechanical Systems, 30 (6), ISSN:1057-7157, ISSN:1941-0158

Photonic metasurfaces, that is, two-dimensional arrangements of designed plasmonic or dielectric resonant scatterers, have been established as a successful concept for controlling light fields at the nanoscale. While the majority of research so far has concentrated on passive metasurfaces, the direct integration of nanoscale emitters into the metasurface architecture offers unique opportunities ranging from fundamental investigations of complex light-matter interactions to the creation of flat sources of tailored light fields. While the integration of emitters in metasurfaces as well as many fundamental effects occurring in such structures were initially studied in the realm of nanoplasmonics, the field has recently gained significant momentum following the development of Mie-resonant dielectric metasurfaces. Because of their low absorption losses, additional possibilities for emitter integration, and compatibility with semiconductor-based light-emitting devices, all-dielectric systems are promising for highly efficient metasurface light sources. Furthermore, a flurry of new emission phenomena are expected based on their multipolar resonant response. This review reports on the state of the art of light-emitting metasurfaces, covering both plasmonic and all-dielectric systems.

We devise automated workflows for the calculation of Helmholtz and Gibbs free energies and their temperature and pressure dependence and provide the corresponding computational tools. We employ nonequilibrium thermodynamics for evaluating the free energy of solid and liquid phases at a given temperature and reversible scaling for computing free energies over a wide range of temperatures, including the direct integration of $P\text{\ensuremath{-}}T$ coexistence lines. By changing the chemistry and the interatomic potential, alchemical and upscaling free energy calculations are possible. Several examples illustrate the accuracy and efficiency of our implementation.

This paper deals with the study of homothetic vector fields of Bianchi type I spacetimes using Rif tree approach. Instead of directly integrating the homothetic symmetry equations, a computer algorithm is used to transform these equations to the reduced involutive form, which splits the problem of integrating these equations into many cases and gives these cases in the form of a tree imposing certain restrictions on the metric functions. Using these restrictions, the set of homothetic symmetry equations is solved to get the explicit form of the metrics and their homothetic vector fields. It is observed that this approach gives some new physically realistic metrics, not given by an earlier study through direct integration technique.

The performance of the developed two point block method designed for two processsors for solving directly non stiff large systems of higher order ordinary differentiall equations (ODEs) has been investigated. The method calculates the numerical solution at two points simultaneously and produces two new equally spaced solution values within a block and it is possible to assign the computational tasks at each time step to a single processor. The algorithm of the method was developed in C language and the parallel computation was done on a parallel shared memory environment. Numerical results are given to compare the efficiency of the developed method to the sequential timing. For large problems, the parallel implementation produced 1.95 speed up and 98% efficiency for the two processors.

International audience; Manufacturing of microsystems based on complex three-dimensional microstructures requires critical steps such as mass calibrations and integration process. However, such steps involve several manipulation steps which are not well controlled thus the fragile 3D microstructures could be damaged or destroyed. In this work, we have demonstrated an AFM based direct mass measurement and manufacturing of 3D helical microswimmer. The proposed method shows to be rapid, repeatable and minimally-destructive thanks to the precise force control and manipulation by AFM. The proposed micromanipulation steps consist of the pick-measure-integrate manipulation steps using van der Waals force-based attachment and the mass measurement by resonant frequency shift. For the testing structures, we fabricated the 6 different types of 3D helical microswimmers vertically fabricated on the conical shape microneedle supports for uniform surface metallization and facile detachment. With the mass measurement sensitivity of 25 Hz/pg and the direct integration to microfluidics, we successfully demonstrated the 3D propulsion and non-contact micromanipulation by 3D helical microswimmer in microfluidics.

This paper addresses the dynamics of locally-resonant sandwich beams, where multi-degree-of-freedom viscously-damped resonators are periodically distributed within the core matrix. On adopting an established model in the literature, which consists of an equivalent single-layer Timoshenko beam coupled with mass-spring-dashpot subsystems representing the resonators, novel and exact analytical expressions are presented for the frequency response and modal response under arbitrary loads. Specifically, the frequency response is built by a direct integration method, while the modal impulse and frequency response functions are derived by a complex modal analysis approach, upon introducing orthogonality conditions pertinent to the complex modes. The expressions obtained for frequency response and modal response hold for any number of resonators and degrees of freedom within the resonators, any number of loads and positions of the loads relative to the resonators. In the proposed complex modal analysis approach, the challenging issue of calculating all complex eigenvalues, without missing anyone, is solved applying a recently-introduced contour-integral algorithm to an exact dynamic stiffness matrix that, here, is built with size depending only on the number of degrees of freedom at the beam ends, regardless of the number of resonators and degrees of freedom within the resonators. Numerical applications prove exactness and robustness of the proposed framework.

Implementing optical-frequency combs with integrated photonics will enable wider use of precision timing signals.Here, we explore the generation of an octave-span, Kerr-microresonator frequency comb, using hybrid integration ofan InP distributed-feedback laser and a SiN photonic-integrated circuit. We demonstrate electrically pumped and fiber-packaged prototype systems, enabled by self-injection locking. This direct integration of a laser and a microresonatorcircuit without previously used intervening elements, like optical modulators and isolators, necessitates understand-ing self-injection-locking dynamics with octave-span Kerr solitons. In particular, system architectures must adjust tothe strong coupling of microresonator back-scattering and laser-microresonator frequency detuning that we uncoverhere. Our work illustrates critical considerations towards realizing a self-referenced frequency comb with integratedphotonics., 9 pages, 4 figures. This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. This article appeared in APL Photonics 6, 026102 (2021) and may be found at https://doi.org/10.1063/5.0035452

High damping rubber bearings show highly nonlinear stress-strain behaviour. Deformation-history integral (DHI) model which can estimate small strain stiffness degradation and nonlinear plasticity via a relatively simple innovative formulation is implemented in this study to model HDRB as the rehabilitation method for a seismically vulnerable building. Considered structure in this study is a three-dimensional, four-story steel frame residential building with a concentrically braced system. Nonlinear direct integration time history analysis and plastic hinges approach were implemented to evaluate structural behaviour of considered structure. It was observed that structural responses enhanced significantly after rehabilitation. Absolute maximum base shear values decreased 61.8% and 92.2% in the worst and best cases, respectively. Most of structural elements remained elastic after rehabilitation and required performance level was satisfied. publishedVersion

We present Terrestrial Exoplanet Simulator (tes), a new n-body integration code for the accurate and rapid propagation of planetary systems in the presence of close encounters. tes builds upon the classic Encke method and integrates only the perturbations to Keplerian trajectories to reduce both the error and runtime of simulations. Variable step size is used throughout to enable close encounters to be precisely handled. A suite of numerical improvements is presented that together make tes optimal in terms of energy error. Lower runtimes are found in the majority of test problems considered when compared to direct integration using ias15. tes is freely available.

The continuous development of computer technology has made it applicable in many scientific fields, including research into a wide range of processes in agricultural machines. It allows the simulation of very complex physical phenomena, including grain motion. A recently discovered discrete element method (DEM) is used for this purpose. It involves direct integration of equations of grain system motion under the action of various forces, the most important of which are contact forces. The method&rsquo, s accuracy depends mainly on precisely developed mathematical models of contacts. The creation of such models requires empirical validation, an experiment that investigates the course of contact forces at the moment of the impact of the grains. To achieve this, specialised test stations equipped with force and speed sensors were developed. The correct selection of testing equipment and interpretation of results play a decisive role in this type of research. This paper focuses on the evaluation of the force sensor dynamic properties&rsquo, influence on the measurement accuracy of the course of the plant grain impact forces against a stiff surface. The issue was examined using the computer simulation method. A proprietary computer software with the main calculation module and data input procedures, which presents results in a graphic form, was used for calculations. From the simulation, graphs of the contact force and force signal from the sensor were obtained. This helped to clearly indicate the essence of the correct selection of parameters used in the tests of sensors, which should be characterised by high resonance frequency.

Focus of this paper is the development of a fast semi-analytical framework to address the nonlinear vibration response of plates with Variable Stiffness (VS) configuration. A formulation is developed based on a mixed variational theorem. A Ritz-like approach is employed for handling the spatial dependence, whilst several techniques are developed and compared for the temporal dependence: the method of averaging, a perturbation approach , an iterative procedure based on the Harmonic Balance Method (HBM) and a direct integration method. The proposed framework allows fast parametric studies to be performed for assessing the nonlinear vibration response of VS plates. The comparison against reference results demonstrates the validity of the proposed formulations in capturing the nonlinear free and forced responses with relative computational ease. This aspect is further exploited by presenting parametric studies, where the role of fiber path and boundary conditions is assessed. These studies aim at providing further understanding into the underlying mechanical response and illustrate the potential of the proposed semi-analytical approaches as a valuable mean to assist the design of VS plates.

International audience; A chemistry reduction approach based on machine learning is proposed and applied to direct numerical simulation (DNS) of a turbulent non-premixed syngas oxy-flame interacting with a cooled wall. The training and the subsequent application of artificial neural networks (ANNs) rely on the processing of 'thermochemical vectors' composed of species mass fractions and temperature (ANN input), to predict the corresponding chemical sources (ANN output). The training of the ANN is performed aside from any flow simulation, using a turbulent non-adiabatic non-premixed micro-mixing based canonical problem with a reference detailed chemistry. Heat-loss effects are thus included in the ANN training. The performance of the ANN chemistry is then tested aposteriori in a two-dimensional DNS against the detailed mechanism and a reduced mechanism specifically developed for the operating conditions considered. Then, three-dimensional DNS are performed either with the ANN or the reduced chemistry for additional a-posteriori tests. The ANN reduced chemistry achieves good agreement with the Arrhenius-based detailed and reduced mechanisms, while being in terms of CPU cost 25 times faster than the detailed mechanism and 3 times faster than the reduced mechanism when coupled with DNS. The major potential of the method lies both in its data driven character and in the handling of the stiff chemical sources. The former allows for easy implementation in the context of automated generation of case-specific reduced chemistry. The latter avoids the Arrhenius rates calculation and also the direct integration of stiff chemistry, both leading to a significant CPU time reduction.

On the basis of a generalized interdisciplinary method that consists of a modification of Hamilton–Ostrogradski principle by expanding the Lagrange function with two components that address the functions of dissipation energy and the energy of external conservative forces, a mathematical model is presented of an electromechanical system that consists of the force section of a magneto-levitation non-contact maglev suspension in a prototype traction vehicle. The assumption that magnetic potential hole, generated naturally by means of cryogenic equipment, is present in the levitation suspension, serving to develop the model system. Contrary to other types of magnetic cushion train suspensions, for instance, maglev–Shanghai or Japan–maglev, this suspension does not need a complicated control system, and levitation is possible starting from zero train velocity. As high-temperature superconductivity can be generated, the analysis of levitation systems, including the effect of magnetic potential holes, has become topical. On the basis of the model of a prototype maglev train, dynamic processes are analyzed in the levitation system, including the effect of the magnetic potential hole. A system of ordinary differential equations of the dynamic state is presented in the normal Cauchy form, which allows for their direct integration by both explicit and implicit numerical methods. Here, the results of the computer simulations are shown as figures, which are analyzed.

Hybrid simulation (HS) is an advanced simulation method that couples experimental testing and analytical modeling to better understand structural systems and individual components&rsquo, behavior under extreme events such as earthquakes. Conducting HS and real-time HS (RTHS) can be challenging with complex analytical substructures due to the nature of direct integration algorithms when the finite element method is employed. Thus, alternative methods such as machine learning (ML) models could help tackle these difficulties. This study aims to investigate the quality of the RTHS tests when a deep learning algorithm is used as a metamodel to represent the dynamic behavior of a nonlinear analytical substructure. The compact HS laboratory at the University of Nevada, Reno was utilized to conduct exclusive RTHS tests. Simulating a braced frame structure, the RTHS tests combined, for the first time, linear brace model specimens (physical substructure) along with nonlinear ML models for the frame (analytical substructure). Deep long short-term memory (Deep-LSTM) networks were employed and trained to develop the metamodels of the analytical substructure using the Python environment. The training dataset was obtained from pure analytical finite element simulations for the complete structure under earthquake excitation. The RTHS evaluations were first conducted for virtual RTHS tests, where substructuring was sought between the LSTM metamodel and virtual experimental substructure. To validate the proposed RTHS testing methodology and full system, several actual RTHS tests were conducted. The results from ML-based RTHS were evaluated for different ML models and compared against results from conventional RTHS with finite element models. The paper demonstrates the potential of conducting successful experimental RTHS using Deep-LSTM models, which could open the door for unparalleled new opportunities in structural systems design and assessment.

In this article, we examine a (3+1)-dimensional generalized breaking soliton equation which is highly applicable in the fields of engineering and nonlinear sciences. Closed-form solutions in the form of Jacobi elliptic functions of the underlying equation are derived by the method of Lie symmetry reductions together with direct integration. Moreover, the (G&prime, /G)-expansion technique is engaged, which consequently guarantees closed-form solutions of the equation structured in the form of trigonometric and hyperbolic functions. In addition, we secure a power series analytical solution of the underlying equation. Finally, we construct local conserved vectors of the aforementioned equation by employing two approaches: the general multiplier method and Ibragimov&rsquo, s theorem.

In this study we look into the interference effect in multi-thread molecular junctions in between carbon-nanotube (CNT) electrodes of assorted edges. From the tube end into the tube bulk of selected CNTs, we investigate surface Green’s function and layer-by-layer local density of states (LDOS), and find that both the cross-cut and the angled-cut armchair CNTs exhibit 3-layer-cycled LDOS oscillations. Moreover, the angled-cut armchair CNTs, which possess a zigzag rim at the cut, exhibit not only the oscillations, but also edge state component that decays into the tube bulk. In the case of cross-cut zigzag CNTs, the LDOS shows no sign of oscillations, but prominent singularity feature due to edge states. With these cut CNTs as leads, we study the single-polyene and two-polyene molecular junctions via both ab initio and tight-binding model approaches. While the interference effect between transport channels is manifested through our results, we also differentiate the contributions towards transmission from the bulk states and the edge states, by understanding the difference in the Green’s functions obtained from direct integration method and iterative method, separately.

In this paper, the periodic solution for the local fractional Boussinesq equation can be obtained in the sense of the local fractional derivative. It’s given by applying direct integration with symmetry condition. Meanwhile, the periodic solution of the non-differentiable type with generalized functions defined on Cantor sets is analyzed. As a result, we have a new point to look the local fractional Boussinesq equation through the local fractional derivative theory.

The aim of this study is to investigate the dynamic response of axially moving two-layer laminated plates on the Winkler and Pasternak foundations. The upper and lower layers are formed from a bidirectional functionally graded (FG) layer and a graphene platelet (GPL) reinforced porous layer, respectively. Henceforth, the combined layers will be referred to as a two-dimensional (2D) FG/GPL plate. Two types of porosity and three graphene dispersion patterns, each of which is distributed through the plate thickness, are investigated. The mechanical properties of the closed-cell layers are used to define the variation of Poisson’s ratio and the relationship between the porosity coefficients and the mass density. For the GPL reinforced layer, the effective Young’s modulus is derived with the Halpin-Tsai micro-system model, and the rule of mixtures is used to calculate the effective mass density and Poisson’s ratio. The material of the upper 2D-FG layer is graded in two directions, and its effective mechanical properties are also derived with the rule of mixtures. The dynamic governing equations are derived with a first-order shear deformation theory (FSDT) and the von K´arm´an nonlinear theory. A combination of the dynamic relaxation (DR) and Newmark’s direct integration methods is used to solve the governing equations in both time and space. A parametric study is carried out to explore the effects of the porosity coefficients, porosity and GPL distributions, material gradients, damping ratios, boundary conditions, and elastic foundation stiffnesses on the plate response. It is shown that both the distributions of the porosity and graphene nanofillers significantly affect the dynamic behaviors of the plates. It is also shown that the reduction in the dynamic deflection of the bilayer composite plates is maximized when the porosity and GPL distributions are symmetric.

A static and dynamic large deformation analysis of a tapered beam subjected to concentrated and distributed loads is presented in this paper by using a direct integration technique. The bending stiffness of the beam is coordinate dependent. The nonlinear differential equation is numerically solved using an iterative technique without an algebraic equation solver, thus the computational effort can be reduced. A concentrated mass fixed at the free end and suddenly released is studied, and the time-dependent displacements are presented. Comparison has been made with solutions obtained using Finite Element Analysis and excellent agreement is achieved.

We show that direct Feynman-parametric loop integration is possible for a large class of planar multi-loop integrals. Much of this follows from the existence of manifestly dual-conformal Feynman-parametric representations of planar loop integrals, and the fact that many of the algebraic roots associated with (e.g. Landau) leading singularities are automatically rationalized in momentum-twistor space---facilitating direct integration via partial fractioning. We describe how momentum twistors may be chosen non-redundantly to parameterize particular integrals, and how strategic choices of coordinates can be used to expose kinematic limits of interest. We illustrate the power of these ideas with many concrete cases studied through four loops and involving as many as eight particles. Detailed examples are included as ancillary files to this work's submission to the arXiv., Comment: 55 pages, 61 figures; detailed examples are included as ancillary files. Minor corrections and slight elaborations in v2

The non-linear partial differential (2+1) dimensional Breaking Soliton equation is studiedby using the direct integration and homotopy perturbation method. In this study, we use directintegration to obtain the known solution in the literature in practical and shortest way by assigningsome special values to the constants in the solutions of the (2+1) dimensional Breaking Solitonequation. We also obtain same type solution for (2+1) dimensional Breaking Soliton equation byusing the homotopy perturbation method with one iteration. Similarly, same type solutions can bedone different methods such as (G'/G)-expansion method.

The seamless combination of plasmonic structures with metal oxides and in particular with 2D materials has attracted significant recent interests. Here, a novel approach to grow molybdenum disulfide (MoS2) is presented: an optically active 2D material, directly onto plasmonic nanoscale gold disks via a surface diffusion delivery of Mo from within the nanostructure and a sulfidation process. X-ray photoelectron spectroscopy and Raman spectroscopy measurements demonstrate the existence and the reaction process of few layered MoS2. Delivery of Mo from within the nanostructure and direct growth of MoS2 has the potential to form better defined metal/MoS2 interfaces compared to exfoliation routes. This facile approach has the potential for application in photodetector or other devices.

To determine the influence of temperature on the mechanical properties of crane metal structures, three Q355 alloy steel samples were processed and their elastic moduli were tested at different temperatures using a metal tension test bed. The constitutive equation for the elastic modulus of Q355 alloy steel at different temperatures was predicted using test data and a neural network algorithm. Based on crane structural characteristics and the principle of system dynamics, a coupling vibration model was established that included the crane flexible girder, cabin, trolley, crane, and temperature. System motion equations were established according to the Lagrange equation, and the approximate solution of nonlinear system vibration was solved by the direct integration method (the Newmark method). The dynamic characteristics of the main beam and cabin were analyzed at different temperatures, as well as safety during service. The results show that, with increasing temperature, the maximum midspan displacement of the main beam increases gradually, by 14.3%, 21.4%, and 57.1% at temperatures of 300°C, 400°C, and 600°C, respectively. The cabin vibration displacement increases with temperature, by up to 32.5% at 600°C, but the influence of temperature on cabin vibration acceleration is not obvious. It was concluded that the influence of temperature on the dynamic characteristics of the main beam must be considered during the design stage of cranes. The proposed model and analysis method provide a theoretical basis for the design of casting cranes according to temperature.

Based on Mindlin plate theory and finite element method (FEM), dynamic response analysis of sandwich composite plates with auxetic honeycomb core resting on the elastic foundation (EF) under moving oscillator load is investigated in this work. Moving oscillator load includes spring-elastickand damperc. The EF with two coefficients was modelled by Winkler and Pasternak. The system of equations of motion of the sandwich composite plate can be solved by Newmark’s direct integration method. The reliability of the present method is verified through comparison with the results other methods available in the literature. In addition, the effects of structural parameters, material properties, and moving oscillator loads to the dynamic response of the auxetic honeycomb plate are studied.

We reproduce the two-loop seven-point remainder function in planar, maximally supersymmetric Yang-Mills theory by direct integration of conformally-regulated chiral integrands. The remainder function is obtained as part of the two-loop logarithm of the MHV amplitude, the regularized form of which we compute directly in this scheme. We compare the scheme-dependent anomalous dimensions and related quantities in the conformal regulator with those found for the Higgs regulator., 22 pages, 1 figure. Detailed results available in an ancillary file

The energy dissipated in hysteretic damping is independent of cyclic frequency, which agrees with the experimental results of energy dispersion of many materials under cyclic loading. Despite these desirable properties, hysteretic damping suffers from a notable drawback, the direct integration solution of the equation of motion is divergent. In this paper, a virtual initial condition is proposed to address the instability of the solution. The new method develops virtual initial conditions associated to the real initial conditions, which make the direct integration solution eliminate the divergence term of the complementary solution and converge to the exact solution. The stability and accuracy of the proposed direct integration method are demonstrated to be effective in solving the divergence problem by the comparison of the numerical and theoretical solutions on the free and forced vibration of a system with hysteretic damping.

A (3+1)-D generalized B-type KP-Boussinesq equation, which was recently formulated in the literature, is investigated here from Lie group standpoint. A solution is obtained by Lie symmetry reductions and direct integration in terms of incomplete elliptic integral. Furthermore, hyperbolic and trigonometric functions solutions are derived by invoking the (G′/G)- expansion method. Finally, we construct conservation laws of the aforementioned equation by utilizing the multiplier method and conservation theorem due to Ibragimov. Keywords: A (3+1)-dimensional generalized BKP-Boussinesq equation, Lie point symmetries, Exact solutions, Incomplete elliptic integral, (G′/G)-expansion method, Conservation laws

In this paper we study the calculation of multiloop Feynman integrals that cannot be expressed in terms of multiple polylogarithms. We show in detail how certain types of two- and three-point functions at two loops, which appear in the calculation of higher order corrections in QED, QCD and in the electroweak theory (EW), can naturally be expressed in terms of a recently introduced elliptic generalisation of multiple polylogarithms by direct integration over their Feynman parameter representation. Moreover, we show that in all examples that we considered a basis of pure Feynman integrals can be found.

The purpose of this paper is to find conformal vector fields of some perfect fluid Kantowski-Sachs and Bianchi type III space-times in the f(R) theory of gravity using direct integration technique. In this study there exists only eight cases. Studying each case in detail, we found that in two cases proper conformal vector fields exist while in the rest of six cases conformal vector fields become Killing vector fields. The dimension of conformal vector fields is either 4 or 6., 12 pages

In the context of improving energy efficiency and thermal comfort in the building, the use of phase change materials (PCMs) is one of the suggested solutions. The proposed integration solutions concern the building envelope as well as the applications related to its operation. The study of the incorporation of PCM in the walls of the building was the subject of numerous works. However, the antisymmetric character of storing/recovering energy management in the walls is less controlled and do not fit the optimal conditions. In this study, a solution based on the direct integration of a stabilized PCM (gel) in an envelope including ventilation channels, was proposed to overcome this problem of antisymmetry storing/recovering and fitting with different fixed ambient conditions. The final aim is to develop the optimization strategy of a wall combining the heavy inertia offered by the PCM, intra-ventilation control and the contribution to air renewal energy demand. In this context, an experimental study of a concrete block system is conducted to test the thermal response of this configuration by the application of cyclic solicitations. The comprehension of this integrated constructive solution essentially passes by the possession of validated numerical tools. For this, two models have been developed. The first model using the electrical–thermal analogy, based on an RC equivalence, is distinguished by its relative simplicity and weak time computing demand. Each of these two factors, R and C summarise the system properties and has a direct influence on the building transient simulations over a year. The second one is based on direct numerical simulation DNS of the energy and fluid flow equations using commercial code COMSOL Multiphysics. Such DNS is time consuming and could not be used to simulate over a year but aims only to validate the first RC circuit approach. A comparison of these two models with the idealised experimental data was carried out and allowed the validation of the thermal behaviour of the solution based on the integration of the PCM with core ventilation.

The creation of fabrics capable of dynamically communicating information would have a great impact on future smart fabric technologies for applications ranging from fashion and entertainment to biomedical monitoring. Typically, state-of-the-art displays are fabricated onto flexible substrates and then mounted onto textiles. However, recent progress in fabricating electroluminescent (EL) fiber-shaped devices that can be directly integrated into knitted and woven structure has unlocked new opportunities for developing fabric-integrated displays. Here, a novel method of directly integrating an EL system into a network of fibers to create a dynamic knit display is presented. A 4-pixel prototype with individually controllable pixels disposed within a knitted fabric matrix is demonstrated. The control system and structure of isolated pixels in the knit fabric matrix are explained. Important display features based on the prototype performance that demonstrate the current and future potential of this structure are reported.

In this article a variable order variable step size technique in backwards difference form is used to solve nonlinear Riccati differential equations directly. The method proposed requires calculating the integration coefficients only once at the beginning, in contrast to current divided difference methods which calculate integration coefficients at every step change. Numerical results will show that the variable order variable step size technique reduces computational cost in terms of total steps without effecting accuracy.

New applications like 5G and car radar require higher operating frequencies. For higher frequencies the size of a typical packaged IC is of the same order of magnitude of one or more waveguide cross-sections, giving the opportunity to use the waveguide as an IC to waveguide interconnect. The excitation of an in-package waveguide needs to be modeled to design the interconnect. This paper shows that a simplified Method Of Moments (MOM) model is suitable for modeling a dipole excitation. Results for the MOM model shows good comparison with CST and an analytical model. Furthermore, the MOM model is converted into a circuit model for a direct integration with IC design tools.

Integrating sensors into machine parts is a necessary step for the development of smart or intelligent components. Sensors integrated into materials such as concrete, fiber compounds, or metals are already used to measure strain, temperature, or corrosion. The integration is mostly done during fabrication, where the sensor is recast in the material during processing. However, approaches to integrate sensors into parts fabricated by additive manufacturing are still rarely found. Especially in the case of rapid prototyping, additive techniques are already substituting the machining of parts using classical technologies like cutting, drilling and milling. To characterize such 3-D-printed machine parts the direct integration of sensing elements is the next logical step. This can be done in multi-material printing by using insulating, magnetic, and conductive materials. In the case of single material printing, our idea is to integrate a sensing element during the printing process itself. As proof-of-concept, we present the functionalization of 3-D-printed screws. Strain gauges screen-printed on a 6 µm thick foil are interposed into the 3-D part during microstereolithography printing. We measure the torsional strain in the screw head to calculate the prestressing force in screws made from different plastic materials. We also analyze the defect effect by comparing it to screws without integrated elements.

The present study analyzes the fundamental properties of a rate-dependent cohesive model applied to the description of dynamic mode-II crack propagation. To make a semi-analytical treatment possible, the idealised problem of a crack along the interface between a semi-infinite elastic layer and a rigid substrate is considered. Solutions corresponding to the propagation of the crack tip at a constant speed are constructed. Using asymptotic properties of the solution far from the crack tip allows obtaining the complete solution of the boundary value problem by direct integration without iterations, using a specific form of the shooting method. By conversion of the problem to dimensionless variables, the behavior of the system for all possible crack velocities and arbitrary combinations of material and geometric parameters can be characterized. The dependence of fracture energy and other important characteristics on model parameters and the crack speed can then be analyzed. Even if the approach is applied to a specific form of damage rate dependence and motivated by the analysis of delamination propagation, the same technique could be used for other classes of interfacial cohesive rate-dependent models.

Membrane-based oxy-combustion is a promising technology for energy efficient combustion of carbon-containing fuels with the simultaneous opportunity to capture CO2 from the resulting exhaust gas. However, oxy-combustion conditions result in special demands on the design of the ceramic membrane components due to the high pressure and temperature applied. Therefore, we have developed a planar membrane design for 4-end operation using asymmetric membranes of La0.6Sr0.4Co0.2Fe0.8O3−δ. FEM and CFD simulations have been performed in order to develop an internal channel structure that allows withstanding pressures of 5 bar on the feed side while achieving the desired O2 concentrations of 27% in the sweep gas, i.e. CO2, and an oxygen recovery rate from the feed gas of 86% at the same time. Due to the symmetric design of the membrane components, they are scalable and adaptable in size. This design has been realized in a process chain from powder to the final component consisting of thin 20 µm Membrane layer, support with 38% porosity, an inner channelled architecture and a thin (3–5 µm) porous activation layer. Particular emphasis was laid on scalable manufacturing processes in order to ensure transferability to industrial scale. The process chain is also applicable to other membrane materials suitable for any application of interest. Finally, the reproducible processing was successfully demonstrated by the fabrication of membrane components in lengths of 100 mm and widths of 70 mm.

Taken the flexible shaft and elastic disk rotor system as the research object, vibration differential equations are established by the modal synthesis method. Based on the Runge–Kutta method of direct integration, dynamic equations are solved successfully. Then, the effects of Alford force caused by the airflow excitation are researched on the stability and dynamic response. The results show modal vibration of the disk takes a great effect on the coupled natural frequency of shaft transverse vibration in the high rotational speed region. The effect of shaft-disk coupling makes rotor frequency to decrease, and different rotational speeds have little effect on rotor frequency. Eccentric distance is sensitive to the amplitude of rotor response, but it has little effect on rotor stability, motion law, and relative relationship of two response frequencies. The proportion of rotor responses caused by aerodynamic excitation force becomes larger with the increase of rotational speed and disk radius. However, the proportion decreases with the second support moving to the right, and it is helpful for the stable operation of the rotor system.

We propose a simplified numerical technique to quantify the effects of non-linear stiffness in MEMS resonators and we validate our approach on a clamped–clamped beam, a softening Disk Ring Gyroscope (DRG) and a shallow arch showing internal resonance. We generate a Reduced Order Model (ROM) which is integrated with either a direct integration approach or a continuation technique with arc length control. Finally we compare and validate the results with a full FEM model.

Direct integration of Carbon Nanotubes (CNTs) in CMOS is important for commercially manufacturing low-cost CNT-based sensors. In such compact sensors, CNTs would act as sensing element, and CMOS circuits would process relevant signals from the CNTs. CNTs can be directly synthesized and integrated into CMOS by local thermal chemical vapor deposition (CVD), where a hot spot of 900 °C can be generated by CMOS micro-heaters. However, a sufficient thermal gradient between the micro-heaters and nearest CMOS devices is a prerequisite to ensure non-destructive temperature (

We present a theoretical and numerical framework -- which we dub the Direct Integration Method (DIM) -- for simple, efficient and accurate evaluation of surface wave models allowing presence of a current of arbitrary depth dependence, and where bathymetry and ambient currents may vary slowly in horizontal directions. On horizontally constant water depth and shear current the DIM numerically evaluates the dispersion relation of linear surface waves to arbitrary accuracy, and we argue that for this purpose it is superior to two existing numerical procedures: the piecewise-linear approximation and a method due to \textit{Dong \& Kirby} [2012]. The DIM moreover yields the full linearized flow field at little extra cost. We implement the DIM numerically with iterations of standard numerical methods. The wide applicability of the DIM in an oceanographic setting in four aspects is shown. Firstly, we show how the DIM allows practical implementation of the wave action conservation equation recently derived by \textit{Quinn et al.} [2017]. Secondly, we demonstrate how the DIM handles with ease cases where existing methods struggle, i.e.\ velocity profiles $\mathbf{U}(z)$ changing direction with vertical coordinate $z$, and strongly sheared profiles. Thirdly, we use the DIM to calculate and analyse the full linear flow field beneath a 2D ring wave upon a near--surface wind--driven exponential shear current, revealing striking qualitative differences compared to no shear. Finally we demonstrate that the DIM can be a real competitor to analytical dispersion relation approximations such as that of \textit{Kirby \& Chen} [1989] even for wave/ocean modelling., Comment: 25 pages, 8 figures, 1 table, submitted to J. Geophys. Res.: Oceans

The relativistic three-boson system with zero-range interaction has recently been investigated by our group by using the valence Light-Front and the four-dimensional Euclidean Bethe-Salpeter equations. We review some results from those studies, focusing on the impact of higher-Fock contributions on the computed physical quantities. Furthermore, we have also solved the Bethe-Salpeter equation by direct integration in Minkowski space and some first results from these calculations are presented. A full solution in Minkowski space is important since it gives direct access to dynamical observables such as electromagnetic form factors and momentum distributions. The obtained results are in fair agreement with the ones computed in Euclidean when the comparison is suitable.

The distinctive paper presents the general papers of the science-based universal software system “STADYO” intended for the numerical solution of stationary and nonstationary problems of field theory, analy-sis of static, temperature and dynamic stress-strain state (SSS), stability and strength of arbitrary combined me-chanical systems (massive-shell-lamellar-membrane-rod with “rigid” bodies, fluid cavities and internal bonds, isotropic and orthotropic materials) into a flat axis, axisymmetric and three-dimensional linear and nonlinear formulations. The composition of the “STADYO” software system is briefly described; in terms of its theoretical foundations, the main provisions and matrix relationships of the superelement method (which is known to be one of the most effective ways to increase the universality and increase the computational efficiency of finite element algorithms) are presented, as well as methods for dynamic synthesis of substructures and submodelling. The su-perelement algorithm is also extended to solving a system of linear equations at each step of the implicit scheme of direct integration of the equations of motion, and at each iteration in the calculation of natural oscillations; however, an alternative and more efficient approach consists in constructing special superelement algorithms based on the direct condensation of the equations of motion and ideologically close to the method of dynamic synthesis of substructures. The submodelling options, in particular, are important for the refined analysis of the three-dimensional SSS of heavily loaded component parts of the objects under consideration. In general, the presentation of the global design model of the system as a set of substructures is also very convenient for its de-scription and creates the prerequisite for the creation (application) of effective pre- and postprocessor software. The paper also provides information on verification and experience in the use of the “STADYO” software sys-tem, as well as prospects for development.

This paper focuses on the methods of calculating load-bearing systems in the case of a failure of a structural element. This kind of failure makes it necessary to assess further behavior of the structure with a possibility of the progressive collapse development. The stress-strain state analysis of a load-bearing system in the case of a failure of a structure is carried out by two main methods – static and dynamic calculation. It is shown that the static calculation (quasi-static analysis using the dynamic amplification factor) is not a universal method. This paper justifies the application of the direct dynamic calculation in the mode of direct integration of motion for the design analysis of load-bearing systems with high rigidity stories (protection structures for a load-bearing system). It also gives recommendations for selecting parameters of the direct dynamic calculation in the case of a failure analysis of a bearing structure.

International audience; The present work has been conducted in order to develop a novel approach to predict the inhomogeneous flow of a 20MnCr5 steel during an axisymmetric hot compression test, by using the element-free Galerkin (EFG) method under a differential constitutive description. The governing equations have been solved on the basis of the EFG global weak formulation. A detailed explanation concerning the characteristics inherent to the application of the EFG method to this problem, has also been provided. Furthermore, a return mapping algorithm for the solution of associative von Mises inelastic problems, has been formulated for the differential constitutive description employed in this communication, namely, a differential return mapping algorithm (DRMA). The feasibility and suitability of the EFG method for solving the axial compression problem has been shown by comparing its results with a FEM based solution employing a simple constitutive description. The reliability of the proposed DRMA has been demonstrated by a comparison of a homogeneous deformation numerical test with the experimental and direct integration results reported in a previous communication. Finally, the EFG model has been used to predict the stress, strain and volume fraction recrystallized distributions under steady and transient nominal strain rate and temperature deformation conditions. These parametric studies have been carried out by considering the differential constitutive description, but also a conventional integrated constitutive model of a 20MnCr5 steel. The results have revealed the suitability of the EFG formulation under the proposed DRMA, for predicting the performance of an axisymmetric hot compression test. The differences between the use of differential and integrated constitutive descriptions on the performance of hot-working processes under inhomogeneous deformation conditions, have also been evidenced in this research work.

Wear of a cylindrical punch composed by two different materials alternatively distributed in annular forms is studied with the method of dimensionality reduction (MDR). The changes in surface topography and pressure distribution during the wear process is obtained and validated by the boundary element method (BEM). The pressure in each annular ring approaches a constant in a stationary state where the surface topography does not change any more. Furthermore, in an easier manner, using direct integration, the limiting profile in a steady wear state is theoretically calculated, as well as the root mean square (RMS) of its surface gradient, which is closely related to the coefficient of friction between this kind of surface and an elastomer. The dependence on the wear coefficients and the width of the annular areas of two phases is obtained.

This paper presents the methodology and challenges experienced in the microfabrication, packaging, and integration of a fixed-fixed folded spring piezoelectric energy harvester. A variety of challenges were overcome in the fabrication of the energy harvesters, such as the diagnosis and rectification of sol-gel PZT film quality and adhesion issues. A packaging and integration methodology was developed to allow for the characterizing the harvesters under a base vibration. The conditioning circuitry developed allowed for a complete energy harvesting system, consisting a harvester, a voltage doubler, a voltage regulator and a NiMH battery. A feasibility study was undertaken with the designed conditioning circuitry to determine the effect of the input parameters on the overall performance of the circuit. It was found that the maximum efficiency does not correlate to the maximum charging current supplied to the battery. The efficiency and charging current must be balanced to achieve a high output and a reasonable output current. The development of the complete energy harvesting system allows for the direct integration of the energy harvesting technology into existing power management schemes for wireless sensing.

Pulsed-field gradient (PFG) diffusion experiments can be used to measure anomalous diffusion in many polymer or biological systems. However, it is still complicated to analyze PFG anomalous diffusion, particularly the finite gradient pulse width (FGPW) effect. In practical applications, the FGPW effect may not be neglected, such as in clinical diffusion magnetic resonance imaging (MRI). Here, two significantly different methods are proposed to analyze PFG anomalous diffusion: the effective phase-shift diffusion equation (EPSDE) method and a method based on observing the signal intensity at the origin. The EPSDE method describes the phase evolution in virtual phase space, while the method to observe the signal intensity at the origin describes the magnetization evolution in real space. However, these two approaches give the same general PFG signal attenuation including the FGPW effect, which can be numerically evaluated by a direct integration method. The direct integration method is fast and without overflow. It is a convenient numerical evaluation method for Mittag-Leffler function-type PFG signal attenuation. The methods here provide a clear view of spin evolution under a field gradient, and their results will help the analysis of PFG anomalous diffusion.

Finding efficient and accurate solution methods for nonlinear equilibrium equations is a challenging task. This is the case of systems with friction-induced nonlinearities, e.g., friction-damped turbomachinery assemblies and automotive applications such as brakes. In order to tackle this strategic task, several methods have been developed, both in the time and in the frequency domains. Time marching methods are regarded as the most accurate option, but their computational cost becomes prohibitive when friction nonlinearities are present. This poses a problem in all those cases where alternative frequency domain methods cannot be applied effectively, e.g., if transients, non-periodic excitation/solution, or highly nonlinear systems are of interest. The purpose of this paper is to propose three independent methods to make time-marching more competitive. Two of these methods can be applied to any existing direct integration scheme with minimal adjustments, but the computational time cut they introduce is significant. The last method is instead tailored for systems where the inertia force contribution is negligible. All methods are thoroughly validated numerically using a standard Newmark- β integration scheme as a reference.