Meyer–Neldel energy in Se-based binary and ternary chalcogenide glasses

This paper investigates the cluster-modified function projective synchronisation (CMFPS) of a generalised linearly coupled network with asymmetric coupling and nonidentical dynamical nodes. A novel synchronisation scheme is proposed to achieve CMFPS in community networks. We use adaptive control method to derive CMFPS criteria based on Lyapunov stability theory. Each cluster of networks is synchronised with target system by state transformation with scaling function matrix. Numerical simulation results are presented finally to illustrate the effectiveness of this method.     

A two-dimensional generalized thermo-hydro-mechanical-coupled problem for a poroelastic half-space

ABSTRACT

This study investigated the effects of coupled thermo-hydro- mechanical dynamics on an isotropic, uniform, fully saturated, and poroelastic half-space subgrade whose surface is subjected to either mechanical force or thermal load. In this paper, our formulation is deduced in the context of two theories of generalized thermoelasticity: the Lord-Shulman theory and the Green-Lindsay theory. We then deduce the general relationships among non-dimensional vertical displacement, excess pore water pressure, vertical stress, and temperature distribution using Normal Mode Analysis (NMA) and depict them graphically. NMA is a method using weighted residuals to derive analytical solutions and can thus solve partial differential equations more quickly compared to other methods. This study continues our work of applying NMA to derive theoretical results in the multi-field coupling of soil. Following the analysis, the theoretical results are illustrated with a numerical example and a Maple program is developed. Furthermore, the differences between the coupled thermo-hydro-mechanical dynamic model (THMD) and the thermo-elastic dynamic model (TED) are presented. This proposed derivation method can be widely applied in the geotechnical engineering field, especially with regard to the mechanical and thermal behaviors of commercial buildings, high-speed railways, and highway energy foundations.     

Response of circular plates to thermal impact

The thermally induced vibrations of simply supported circular plates are investigated analytically. The solution is composed of two parts; the first is obtained by neglecting the inertia term and the second represents the vibrating component which oscillates about the first, due to the effect of the inertia. One of the reasons for separating the solution in two parts is to obtain the complete solution expediently. But when this is represented in non-dimensional form, the quasi-static part has the particular desirable feature that it is independent of the strength of the thermal shock and thus will give an index for the displacement due to the temperature moment if (and only if) the inertia force has a small effect. The basic equation is governed by only one non-dimensional parameter B which contains the density, the thermal diffusivity of the material and the radius of the plate in its numerator, and the flexural rigidity and thickness of the plate in its denominator, all to various powers. B represents the strength of the thermal shock. As B increases the non-dimensional amplitude of the vibration becomes large and the natural frequency decreases.     

Study of a misaligned flexibly coupled shaft system having nonlinear bearings and cyclic coupling stiffness—Theoretical model and analysis

A model which enables dynamic analysis of flexibly coupled misaligned shafts is presented. The model is setup to account for both angular and parallel misalignment in the presence of mass unbalance and incorporates a coupling having angular, torsional and axial flexibility. Among the important features is the ability to simulate both nonlinear bearing stiffness and coupling angular-stiffness anisotropy. The equations of motion are derived for the linear system, extended to include nonlinear bearing effects and subsequently transformed into non-dimensional form for general application. A series of numerical analyses are performed and the influence of important system parameters assessed thereby providing insight to the resulting static and dynamic forces and motions. Angular and parallel misalignments are shown to produce fundamentally different system response. It is found that the static preload induced by both types of misalignment can play a key role in producing complex vibration resulting from it's interaction with rotating-element anisotropy and bearing nonlinear properties. Bearing static forces are altered and rotating elements are subjected to alternating forces which could affect fatigue life. Bearing forces can be further modified by the application of transmitted torque. The potential for great variability in system response is shown to exist due to the participation of numerous influential variables.     

A CONCENTRATED MASS ON THE SPINNING UNCONSTRAINED BEAM SUBJECTED TO A THRUST

The dynamic stability of a spinning unconstrained beam subjected to a pulsating follower forceP₀ +P₁cos Ωt is analyzed. A concentrated mass is located at an arbitrary location on the beam, and the stability of the beam is studied with the mass at various locations. The beam is analyzed using the Timoshenko-type shear deformation theory with the rotary inertia. Hamilton's principle is used to derive the equations of motion, and the spinning speed of the beam with various non-dimensional parameters subjected to a pulsating follower force is investigated. The finite element method is applied to analyze the spinning beam model, and the method of multiple scales is used to investigate the dynamic stability characteristics. A pulsating follower force is applied, and then the stability regions are changed with the transitions of the stability area in many regions. The results show that the concentrated mass increases the dynamic stability of the spinning unconstrained beam subjected to a thrust. As the spinning speed of the beam is increased, the instability regions are reduced, but various slight instability regions are additionally developed.     

Dynamics of a 3dof torsional system with a dry friction controlled path

A three-degrees of freedom semi-definite torsional system representing an automotive driveline is studied in presence of a torque converter clutch that manifests itself as a dry friction path. An analytical procedure based on the linear system theory is proposed first to establish the stick-to-slip boundaries. Smoothened and discontinuous Coulomb friction formulations are then applied to the nonlinear system, and the differential governing equations are numerically solved given harmonic torque excitation and a mean load. Time domain histories illustrating dry friction-induced stick–slip motions are predicted for different saturation torques and system parameters. Approximate analytical solutions based on distinct states are also developed and successfully compared with numerical studies. Analysis shows that the conditioning factor associated with the smoothened friction model (hyperbolic tangent) must be carefully selected. Then nonlinear frequency responses are constructed from cyclic time histories and the stick–slip boundaries predictions (as yielded by the linear system theory) are confirmed. In particular, the effect of secondary inertia is analytically and numerically investigated. Results show that the secondary inertia has a significant influence on the dynamic response. A quasi-discontinuous oscillation is found with the conventional bi-linear friction model in which the secondary inertia is ignored. Finally, our methods are successfully compared with two benchmark analytical and experimental studies, as available in the literature on two-degrees of freedom translational systems.     

Elastic connection disk subjected to periodically fluctuating transmitted torque and rotational speed

Involving the intrinsic power transmission torque/speed coupling characteristics of prime-movers, a rotating elastic connection disk subjected to periodically fluctuating transmitted torque and rotational speed generated by the fluctuation of external loads is investigated. Using Galerkin's method, the rotating elastic connection disk is modeled as a parametrically excited gyroscopic system. The effects of the torque/speed coupling, transmitted torque fluctuation amplitude and frequency, and constant parts of the transmitted torque and the rotational speed on the system dynamic stability are explored for the disk modes possessing different nodal diameters. The rotational speed, transmitted torque and their fluctuations can all result in system instability of the elastic connection disk. The instability can be suppressed or avoided by operating at small amplitude and low frequency of the transmitted torque fluctuation, and by operating in the weakly coupled torque/speed regime of the prime-movers. Low rotational speed avoids the instability in the case of a small transmitted torque, but medium rotational speed operation is valuable to suppress the instability induced by a large transmitted torque and its fluctuation. Instability parameter regions for the positive and negative torque/speed coupling coefficient are roughly similar in shape, but there are some differences in the value of the instability coefficient.     

Synchronisation in networks of delay-coupled type-I excitable systems

We use a generic model for type-I excitability (known as the SNIPER or SNIC model) to describe the local dynamics of nodes within a network in the presence of non-zero coupling delays. Utilising the method of the Master Stability Function, we investigate the stability of the zero-lag synchronised dynamics of the network nodes and its dependence on the two coupling parameters, namely the coupling strength and delay time. Unlike in the FitzHugh-Nagumo model (a model for type-II excitability), there are parameter ranges where the stability of synchronisation depends on the coupling strength and delay time. One important implication of these results is that there exist complex networks for which the adding of inhibitory links in a small-world fashion may not only lead to a loss of stable synchronisation, but may also restabilise synchronisation or introduce multiple transitions between synchronisation and desynchronisation. To underline the scope of our results, we show using the Stuart-Landau model that such multiple transitions do not only occur in excitable systems, but also in oscillatory ones.     

Experimental investigation on synchronization of three co-rotating non-identical coupled exciters driven by three motors

This work is a continuation and verification of the original literature by means of experiment. According to the previously published paper, the criteria of synchronization and stability for three co-rotating three exciters in an analytical form, as well as their numerical results, are directly provided. A synchronization experiment with three exciters is carried out. The experimental data on phase differences, rotational velocities, system responses, coupling torques, and so on, are quantitatively discussed by dividing the operational processes of the system into four stages. The coupling torques, which are the key determining factors for implementing synchronization, are particularly examined to explain the synchronization regime, based on the average energy method. The quality of synchronization is provided, and the noise and uncertainties in the experimental data are analyzed. It is shown that the experimental results obtained concur with the theoretical results.     

Scaling of electromagnetic transducers for shunt damping and energy harvesting

In order for an electromagnetic transducer to operate well as either a mechanical shunt damper or as a vibration energy harvester, it must have good electromechanical coupling. A simple two-port analysis is used to derive a non-dimensional measure of electromechanical coupling, which must be large compared with unity for efficient operation in both of these applications. The two-port parameters for an inertial electromagnetic transducer are derived, from which this non-dimensional coupling parameter can be evaluated. The largest value that this parameter takes is approximately equal to the square of the magnetic flux density times the length of wire in the field, divided by the mechanical damping times the electrical resistance. This parameter is found to be only of the order of one for voice coil devices that weigh approximately 1 kg, and so such devices are generally not efficient, within the definition used here, in either of these applications. The non-dimensional coupling parameter is found to scale in approximate proportion to the device's characteristic length, however, and so although miniaturised devices are less efficient, greater efficiency can be obtained with large devices, such as those used to control civil engineering structures.     

Synchronization in coupled nonidentical incommensurate fractional-order systems

Synchronization of fractional-order nonlinear systems has received considerable attention for many research activities in recent years. In this Letter, we consider the synchronization between two nonidentical fractional-order systems. Based on the open-plus-closed-loop control method, a general coupling applied to the response system is proposed for synchronizing two nonidentical incommensurate fractional-order systems. We also derive a local stability criterion for such synchronization behavior by utilizing the stability theory of linear incommensurate fractional-order differential equations. Feasibility of the proposed coupling scheme is illustrated through numerical simulations of a limit cycle system, a chaotic system and a hyperchaotic system.     

Symmetry induced coupling of cortical feature maps

The mammalian visual cortex maps retinal position (retinotopy) and orientation preference (OP) across its surface. Simultaneous measurements in vivo suggest that positive correlation exists between the location of dislocations in these two maps, contradicting the predictions of classical dimension reduction models. Model symmetries exert a significant influence on pattern development. However, classical models for cortical map formation have inappropriate symmetry properties. By applying equivariant bifurcation theory we derive symmetry induced, model independent coupling of the OP and retinotopic maps and show that this coupling replicates observations.     

On the moment of inertia of a proto neutron star

The influences of σ* and Φ mesons,temperature and coupling constants of nucleons on the moment of inertia of the proto neutron star(PNS) are examined in the framework of relativistic mean field theory for the baryon octet {n,p,Λ,Σ+,Σ0,Σ+,Ξ-,Ξ0} system.It is found that,compared with that without considering σ* and Φ mesons,the moment of inertia decreases.It is also found that the higher the temperature,the larger the incompressibility and symmetry energy coeficient,and the larger the moment of inertia of a PNS.The influence of temperature and coupling constants of the nucleons on the moment of inertia of a PNS is larger than that of the σ* and Φ mesons.     

NON-LINEAR DYNAMICS AND CONTROL OF CHAOS FOR A TACHOMETER

The dynamic behaviors of a rotational tachometer with vibrating support are studied in the paper. Both analytical and computational results are used to obtain the characteristics of the system. The Lyapunov direct method is applied to obtain the conditions of stability of the equilibrium position of the system. The center manifold theorem determines the conditions of stability for the system in a critical case. By applying various numerical analyses such as phase plane, Poincaré map and power spectrum analysis, a variety of periodic solutions and phenomena of the chaotic motion are observed. The effects of the changes of parameters in the system can be found in the bifurcation diagrams and parametric diagrams. By using Lyapunov exponents and Lyapunov dimensions, the periodic and chaotic behaviors are verified. Finally, various methods, such as the addition of a constant torque, the addition of a periodic torque, delayed feedback control, adaptive control, Bang-Bang control, optimal control and the addition of a periodic impulse are used to control chaos effectively.     

Operational criterion for controlled dense coding with non-trivial tripartite entangled states

Hidden hyperchaotic attractors can be generated with three positive Lyapunov exponents in the proposed 5D hyperchaotic Burke–Shaw system with only one stable equilibrium. To the best of our knowledge, this feature has rarely been previously reported in any other higher-dimensional systems. Unidirectional linear error feedback coupling scheme is used to achieve hyperchaos synchronisation, which will be estimated by using two indicators: the normalised average root-mean squared synchronisation error and the maximum cross-correlation coefficient. The 5D hyperchaotic system has been simulated using a specially designed electronic circuit and viewed on an oscilloscope, thereby confirming the results of the numerical integration. In addition, fractional-order hidden hyperchaotic system will be considered from the following three aspects: stability, bifurcation analysis and FPGA implementation. Such implementations in real time represent hidden hyperchaotic attractors with important consequences for engineering applications.     

激光陀螺捷联惯组减振系统动力学特性研究

针对振动环境下激光惯组减振系统的线位移和角位移耦合问题,提出了一种减振器关于其惯性主轴的八点对称布局的减振方案.基于多体动力学理论,建立了激光陀螺捷联惯组减振系统的动力学模型,进行了其减振系统的动力学特性仿真研究.结果表明,该方案可以消除激光惯组减振系统的线位移和角位移耦合关系,满足激光惯组的减振要求,从而获得比较理想...     

The influence of a wieghardt type elastic foundation on the stability of some beams subjected to distributed tangential forces

In this investigation, the influence of a Wieghardt type elastic foundation on the stability of cantilever and clamped-hinged beams subjected to either a uniformly or a linearly distributed tangential force is considered. In addition to the usual transverse foundation modulus, the Wieghardt model includes the effects of inertia and shear deformation in the foundation. Approximate solutions of the Ritz type are obtained for the pertinent eigenvalue problems, and numerical calculations are reported for various combinations of the internal damping, inertia, transverse foundation modulus and shear foundation modulus parameters. The numerical results reveal that, in general, for a fixed value of the transverse foundation modulus parameter κ, an increase in the shear foundation modulus increases the critical load, whereas an increase in the foundation inertia parameter tends to decrease the critical load. The system consisting of a clamped-hinged beam subjected to a uniformly distributed tangential force loses stability through divergence, provided that the value of κ is sufficiently small. However, when κ becomes large enough, stability will be lost through flutter. In this case, the critical load considered as a function of κ possesses a discontinuity at the transition between divergence and flutter, and its value will either increase or decrease, depending upon the degree of damping in the system.     

Improved torque roll axis decoupling axiom for a powertrain mounting system in the presence of a compliant base

The existing torque roll axis decoupling theories for powertrain mounting systems assume a rigid foundation, thus ignoring dynamic interactions between the powertrain and other sub-systems. To overcome this deficiency, a coupled mounting system problem is formulated based on the linear time-invariant system theory. The influence of a compliant base on torque roll axis decoupling is first analytically examined in terms of eigensolutions and frequency responses. Then, a new analytical axiom is proposed based on decoupling indices as well as given the properties of the coupling matrix. Five examples are chosen to examine frequency and time domain responses given the torque excitation along the crankshaft axis. To satisfy the new condition, the mounting system is redesigned in terms of the stiffness rates, mount locations, and orientation angles. The results show that the torque roll axis of the redesigned powertrain mounting system is indeed decoupled in the presence of a compliant base (given oscillating or impulsive torque excitation). Finally, eigensolutions are validated by using published data.     

POWER FLOW ANALYSIS OF INDETERMINATE ROD/BEAM SYSTEMS USING A SUBSTRUCTURE METHOD

Based on the concepts of a subsystem structural dynamics approach, a general power flow analysis of an indeterminate vibrating system consisting of three rods is presented and discussed. This is achieved by complementing the normal dynamic equations with geometrical compatibility equations allowing assessment of power flow dynamic characteristics applied to and excited within the system. The method may be classified as a form of substructuring using free-free interface conditions. The displacement contribution of the external and boundary coupling forces is deduced, permitting the power flow between the interfaces of substructures to be determined. The method presented is used in a power flow analysis of a simple rod truss system and in a more complex system as demonstrated.     

Novel pinning control strategies for synchronisation of complex networks with nonlinear coupling dynamics

This paper considers the global stability of controlling an uncertain complex network to a homogeneous trajectory of the uncoupled system by a local pinning control strategy. Several sufficient conditions are derived to guarantee the network synchronisation by investigating the relationship among pinning synchronisation, network topology, and coupling strength. Also, some fundamental and yet challenging problems in the pinning control of complex networks are discussed: (1) what nodes should be selected as pinned candidates? (2) How many nodes are needed to be pinned for a fixed coupling strength? Furthermore, an adaptive pinning control scheme is developed. In order to achieve synchronisation of an uncertain complex network, the adaptive tuning strategy of either the coupling strength or the control gain is utilised. As an illustrative example, a network with the Lorenz system as node self-dynamics is simulated to verify the efficacy of theoretical results.