In this paper, we propose a reduced-dimensional smoothed particle hydrodynamics (SPH) formulation for quasi-static and dynamic analyses of plate and shell structures undergoing finite deformation and ...large rotation. By exploiting Uflyand–Mindlin plate theory, the present surface-particle formulation is able to resolve the thin structures by using only one layer of particles at the mid-surface. To resolve the geometric non-linearity and capture finite deformation and large rotation, two reduced-dimensional linear-reproducing correction matrices are introduced, and weighted non-singularity conversions between the rotation angle and pseudo normal are formulated. A new non-isotropic Kelvin-Voigt damping is proposed especially for the both thin and moderately thick plate and shell structures to increase the numerical stability. In addition, a shear-scaled momentum-conserving hourglass control algorithm with an adaptive limiter is introduced to suppress the mismatches between the particle position and pseudo normal and those estimated with the deformation gradient. A comprehensive set of test problems, for which the analytical or numerical results from literature or those of the volume-particle SPH model are available for quantitative and qualitative comparison, are examined to demonstrate the accuracy and stability of the present method.
•Two reduced-dimensional linear-reproducing correction matrices.•Weighted non-singularity conversions between the rotation angle and pseudo normal.•Non-isotropic Kelvin-Voigt damping.•A shear-scaled momentum-conserving hourglass control algorithm.
Free vibration behavior of bidirectional-functionally graded, double-tapered rotating micro-beam is investigated. An improved mathematical model based on Timoshenko beam theory and modified couple ...stress theory is developed that includes the effects of geometric non-linearity, spin-softening, Coriolis acceleration and high operating temperature. The problem is formulated in two steps. In the first step, the problem involving time-invariant inertia force due to rotation of the beam with constant angular speed is formulated using minimum potential energy principle and the governing non-linear equations are solved employing an iterative algorithm. In the next step, the free vibration problem is formulated employing Hamilton’s principle and using the tangent stiffness of the deformed configuration induced due to time-invariant inertial loading. The governing equations for free vibration are transformed to state-space to formulate an eigenvalue problem. The governing equations are solved by approximating the displacement fields following Ritz method. The model is successfully validated with the available results. Extensive sets of results are presented for the first two chord-wise and flap-wise modes of vibration in non-dimensional speed versus frequency plane. The effects of different parameters such as size-dependent thickness, axial and thickness gradation indices, taperness parameters, hub parameter, length-thickness ratio, operating temperature and FGM composition are reported.
In this paper, two of the most common calibration methods of synchronous TDCs, which are the bin-by-bin calibration and the average-bin-width calibration, are first presented and compared. Then, an ...innovative new robust calibration method for asynchronous TDCs is proposed and evaluated. Simulation results showed that: (i) For a synchronous TDC, the bin-by-bin calibration, applied to a histogram, does not improve the TDC's differential non-linearity (DNL); nevertheless, it improves its Integral Non-Linearity (INL), whereas the average-bin-width calibration significantly improves both the DNL and the INL. (ii) For an asynchronous TDC, the DNL can be improved up to 10 times by applying the bin-by-bin calibration, whereas the proposed method is almost independent of the non-linearity of the TDC and can improve the DNL up to 100 times. The simulation results were confirmed by experiments carried out using real TDCs implemented on a Cyclone V SoC-FPGA. For an asynchronous TDC, the proposed calibration method is 10 times better than the bin-by-bin method in terms of the DNL improvement.
We study the long-run relationship between public debt and growth in a large panel of countries. Our analysis builds on theoretical arguments and data considerations in modelling the debt–growth ...relationship as heterogeneous across countries. We investigate the debt–growth nexus adopting linear and non-linear specifications, employing novel methods and diagnostics from the time-series literature adapted for use in the panel. We find some support for a negative relationship between public debt and long-run growth across countries, but no evidence for a similar, let alone common, debt threshold within countries.
•We investigate the relationship between public debt and long-run growth in a large sample of countries.•We model the potential nonlinearity within and across countries in the debt–growth relationship.•We use novel methods to take into account parameter heterogeneity and cross-section dependence.•We find support for a negative relationship between debt and growth across countries, but not for a common debt threshold.
Chaos-based encryption schemes have attracted many researchers around the world in the digital image security domain. Digital images can be secured using existing chaotic maps, multiple chaotic maps, ...and several other hybrid dynamic systems that enhance the non-linearity of digital images. The combined property of confusion and diffusion was introduced by Claude Shannon which can be employed for digital image security. In this paper, we proposed a novel system that is computationally less expensive and provided a higher level of security. The system is based on a shuffling process with fractals key along with three-dimensional Lorenz chaotic map. The shuffling process added the confusion property and the pixels of the standard image is shuffled. Three-dimensional Lorenz chaotic map is used for a diffusion process which distorted all pixels of the image. In the statistical security test, means square error (MSE) evaluated error value was greater than the average value of 10000 for all standard images. The value of peak signal to noise (PSNR) was 7.69(dB) for the test image. Moreover, the calculated correlation coefficient values for each direction of the encrypted images was less than zero with a number of pixel change rate (NPCR) higher than 99%. During the security test, the entropy values were more than 7.9 for each grey channel which is almost equal to the ideal value of 8 for an 8-bit system. Numerous security tests and low computational complexity tests validate the security, robustness, and real-time implementation of the presented scheme.
Based on an extended STIRPAT framework, this paper investigates the effects of financial development on carbon emission intensity in OECD countries from linear and non-linear perspectives, where ...financial development is proxied by three dimensions: financial deepening, financial deepening, and financial size, and financial efficiency. Fortunately, three types of financial development significantly alleviate carbon emission intensity. An extended moderation effect model is built to estimate the effect of financial development via information and communication technology on carbon emission intensity. The results reveal that internet-based information and communication technology and service-based information and communication technology are positively correlated with carbon emission intensity. To effectively handle the endogeneity issue triggered by causal relationships between variables and allow potential non-linear nexus, an advanced dynamic panel threshold model incorporating the generalised method of moments is employed to investigate how financial development affects carbon emission intensity under different types of information and communication technology. Empirical evidence demonstrates the significance of the non-linear nexus between financial development and carbon emission intensity. Lastly, heterogeneity analysis demonstrates the existence of heterogeneity associated with institutional quality, degree of economic development, and resource endowment concerning the effect of financial development on carbon emission intensity among the OECD countries.
•Financial development negatively affects carbon emission intensity.•There is a non-linear relationship between financial development and carbon emission intensity.•The reduction effect of financial development on carbon emission intensity exists significantly heterogeneous.•The interaction effect between financial development and ICT on carbon emission intensity is relatively weak.
The driving motor of the electric vehicle (EV) can recover the kinetic energy during normal braking maneuvers by a regenerative function. At the same time, its dynamic torque response proves to be ...accurate and fast for an emergency braking, namely an anti-lock braking, with the coordinated control of the frictional braking system. However, vehicle transmission properties will deteriorate the control performance of the motor, especially in the anti-lock braking process. A novel permanent magnet synchronous motor (PMSM) control method is proposed considering the transmission influence on this high-dynamic braking process of the pure EV. First, the EV's dynamic model, which includes the PMSM field-oriented control model, the transmission dynamic model, and the hydraulic braking system, is built, and the influences of transmission elasticity and backlash non-linearity on the motor-braking torque are analyzed. Then, based on the wheel slip ratio target of the anti-lock braking, the novel mode-switching method for the motor-torque control between the backlash sliding-mode compensation and the elasticity double-closed-loop PID compensation is put forward. Two state-of-the-art anti-lock braking algorithms, which simplify the transmission properties, the slip ratio phase-plane theory, and the sliding-mode control, are compared with the proposed method. Simulation and test-bench experiment results show that, on different test-road surfaces, the mode-switching PMSM control can effectively compensate for transmission effects and significantly improve the EV's anti-lock braking comfort, stability, and maneuverability with fast and accurate motor-torque regulating.
In this paper we will consider the semi‐linear Cauchy problem for wave models with scale‐invariant time‐dependent mass and dissipation and power non‐linearity. The goal is to study the interplay ...between the coefficients of the mass and the dissipation term to prove blow‐up results or global existence (in time) of small data energy solutions.
Summary
Real‐time dynamic hybrid testing (RTDHT) is a state‐of‐the‐art experimental technique for evaluating the performance of a structural system subjected to time‐varying loads. Because of the ...superiority of shaking table for testing rate‐dependent and inertial effect existing in structural system, shaking table‐based RTDHT is an important branch in RTDHT family, in which shaking table is used to impose inertial forces on physical substructure. Owing to the mass of the seismic platform, shaking table has a relatively narrow testing bandwidth akin to a stand‐alone actuator RTDHT system. Furthermore, structure–table interaction confines the physical substructure to a very small mass and linear stage, such that shaking table‐based RTDHT is unable to test the structural performance with consideration of high frequency input or non‐linearity using large‐scale physical substructure. Actually, this is why we develop RTDHT. In this work, a control strategy named full state control via simulation (FSCS) was proposed to extend the testing capacity of shaking table‐based RTDHT. The efficiency of FSCS‐controlled RTDHT for testing high frequency and non‐linear structural performance was verified by a small‐ and large‐scale shaking table‐based RTDHT, respectively.
Static deflection as well as free and forced large-amplitude vibrations of thin rectangular rubber plates under uniformly distributed pressure are investigated. Both physical, through a neo-Hookean ...constitutive law to describe the non-linear elastic deformation of the material, and geometrical non-linearities are accounted for. The deflections of a thin initially flat plate are described by the von Kármán non-linear plate theory. A method for building a local model, which approximates the plate behavior around a deformed configuration, is proposed. This local model takes the form of a system of ordinary differential equations with quadratic and cubic non-linearities. The corresponding results are compared to the exact solution and are found to be accurate. Two models reflecting both physical and geometrical non-linearities and geometrical non-linearities only are compared. It is found that the sensitivity of the deflection to the physically induced non-linearities at moderate strains is significant.
•Static and dynamic analyses of hyperelastic plates.•Material and geometrical non-linearities are taken into account.•A local model keeping only quadratic and cubic non-linearities is developed.•Numerical results are carried out for a rubber plate.•The influence of material non-linearity at moderate strains is significant.
PDF
