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This study investigates the effectiveness of compact, low-profile, lightweight dipole antennas in enhancing resonant frequency reduction for various wireless communication applications. The structural details of these dipole antennas include single and double circular orthogonally coupled split rings, semi-circular orthogonally coupled split rings and spiral springs. These designs produce 66.31%, 69.71%, 73.36%, 75.71% and 88.46% reduction in resonant frequency, respectively, compared to the half-wavelength (λ/2) dipole resonant frequency at 3.81 GHz. The electrical size (ka) is calculated for each case, with results consistently less than 1. Additionally, the 10 dB impedance bandwidth comparison between dipole coupled double semicircular split rings, spiral spring and half-wave dipole is 16.58%, 17.05%, and 10.41%, respectively. Simulated radiation characteristics are reported to be below the acceptable value and the efficiency is also more than 90% for each topology. Prototypes were fabricated to perform measurements and the good agreement between the measurements and simulation results validated the designed antenna. [ABSTRACT FROM AUTHOR]

De-coring is an essential process in the casting process chain, determining the quality and cost of production. In this study, a coupled multibody system (MBS) and finite element modeling (FEM) technique is presented to study the mechanical loads during the de-coring process. The removal of cast-in sand cores from the inner regions of the cast part by de-coring or knocking out is a complex process with dynamic loads. Currently, the process relies upon empirical knowledge and tests. Inorganic sand cores pose additional challenges in the success of the de-coring process. Increasing complexity in geometry and stringent environmental regulations compel a predictive process in the earlier stages of design. Predicting the process' success is challenged by the dynamic non-linearities of the system. The dynamic characteristics and the interaction between hammer and casting were studied here for the first time using an industrial-based test rig, and a novel modeling approach was formulated. The results of the developed model are in good compliance with the experiments. The methodology presented in this study can be used to include a varying number of hammers and loads. The proposed approach presents the possibility to discretize the process and qualitatively assess the process parameters for optimization. [ABSTRACT FROM AUTHOR]

We investigate the existence of collective dynamical states in nonlocally coupled Stuart-Landau oscillators with symmetry breaking included in the coupling term. We find that the radius of nonlocal interaction and nonisochronicity parameter play important roles in identifying the swing of synchronized states through amplitude chimera states. Collective dynamical states are distinguished with the help of strength of incoherence. Different transition routes to multi-chimera death states are analyzed with respect to the nonlocal coupling radius. In addition, we investigate the existence of collective dynamical states including traveling wave state, amplitude chimera state and multi-chimera death state by introducing higher-order nonlinear terms in the system. We also verify the robustness of the given notable properties for the coupled system. [ABSTRACT FROM AUTHOR]

The initial state selected time-dependent wave packet method has been extended to calculate the coupled-channel reaction probabilities with total angular momentum Jtot > 0 for the title reaction with seven degrees of freedom included. Fully converged integral cross sections were obtained for the ground and a number of vibrational excited initial states on a new potential energy surface recently constructed by this group using neural network fitting. As found from a previous study with the centrifugal sudden (CS) approximation, all these initial vibrational excitations investigated in this study enhance the reactivity considerably at a given collision energy, in particular the CH stretch excited state. The energy initially deposited in CH stretch motion is more effective than translational energy on promoting the reaction in the entire energy region, while for CH bending or CD3 umbrella excitations only at the high collision energy the vibrational energy becomes more effective. Our calculations also revealed that the accuracy of the CS approximation considerably deteriorates with the increase of Jtot, in particular on the threshold energy. The CS approximation underestimates the integral cross sections for all these initial states, albeit not very severely. In general, it works better at high collision energies and for vibrationally excited initial states, with the increase of integral cross section. [ABSTRACT FROM AUTHOR]

We report on multilevel bipolar resistance switching in Cu/amorphous-TaOx/Pt structures controlled by a coupled mechanism. The devices could be reproducibly programmed into three nonvolatile resistance states, and the on/off ratios between all neighboring states are >20. It is speculated that the switching between the high resistance state and the intermediate resistance state originates from a phase transformation between Ta2O5 and TaO2, while the low resistance state is induced by the formation of Cu filaments. This structure might be promising for developing multilevel logic and memory devices with high reliability. It may also serve as a model system for investigating the coupling effect between different switching mechanisms. [ABSTRACT FROM AUTHOR]

Highlights • The new Bayes-Mode-ID method is verified by a full-scale coupled-building. • Implementation issues for Bayes-Mode-ID are discussed in detail. • The modal parameters and their uncertainties are obtained by the Bayesian method. • The modal parameters of the building are helpful for structural assessment. Abstract This paper presents a structural assessment project for a construction training center in Hong Kong. The training center consists of coupled main and complementary buildings. Due to the vigorous activities in the training center, the objectives of the project include conducting operational modal analysis (OMA) of the buildings to assess their structural performance and the coupling of vibrations between the two buildings. OMA is conducted using Bayes-Mode-ID recently developed by the authors, which is an efficient Bayesian modal-component-sampling system identification method for field testing of civil engineering structures under ambient vibrations. Implementation issues for Bayes-Mode-ID are discussed in detail for the full-scale coupled structural system. Due to the large number of measurement points (high resolution mode shapes are desired for understanding the coupling behavior of the system) and limited number of sensors, the measurements were divided into 21 setups in order to properly characterize the dynamics of the building. Each setup covered one portion of the training center and the partial mode shapes from different setups were assembled to provide the global mode shapes. By following a Bayesian approach, not only the most probable values (MPVs) of the modal parameters (modal frequencies, modal damping ratios and mode shapes) but also their associated uncertainties can be obtained. The identified modal parameters reveal interesting dynamic behaviors of the coupled-building and they will be helpful for structural assessment and structural health monitoring (SHM) of the training center in the future. [ABSTRACT FROM AUTHOR]

This study determines the aspects of river bathymetry that have the greatest influence on the predictive biases when simulating hyporheic exchange. To investigate this, we build a highly parameterized HydroGeoSphere model of the Steinlach River Test Site in southwest Germany as a reference. This model is then modified with simpler bathymetries, evaluating the changes to hyporheic exchange fluxes and transit time distributions. Results indicate that simulating hyporheic exchange with a high‐resolution detailed bathymetry using a three‐dimensional fully coupled model leads to nested multiscale hyporheic exchange systems. A poorly resolved bathymetry will underestimate the small‐scale hyporheic exchange, biasing the simulated hyporheic exchange towards larger scales, thus leading to overestimates of hyporheic exchange residence times. This can lead to gross biases in the estimation of a catchment's capacity to attenuate pollutants when extrapolated to account for all meanders along an entire river within a watershed. The detailed river slope alone is not enough to accurately simulate the locations and magnitudes of losing and gaining river reaches. Thus, local bedforms in terms of bathymetric highs and lows within the river are required. Bathymetry surveying campaigns can be more effective by prioritizing bathymetry measurements along the thalweg and gegenweg of a meandering channel. We define the gegenweg as the line that connects the shallowest points in successive cross‐sections along a river opposite to the thalweg under average flow conditions. Incorporating local bedforms will likely capture the nested nature of hyporheic exchange, leading to more physically meaningful simulations of hyporheic exchange fluxes and transit times. Article impact statement: Three‐dimensional fully coupled surface water‐groundwater models with detailed river bathymetry contrasts lead to nested multiscale hyporheic exchange systems. [ABSTRACT FROM AUTHOR]

The use of adhesively bonded joints in industrial structures requires reliable tools for the estimation of the failure load. The necessary and sufficient condition to predict the strength of such joints involves the implementation of a coupled stress and energetic criteria. However, its application necessitates the identification of the stress distribution along the adhesive layer, which has been approximated in this paper by a previously published closed‐form solution. This analysis along with finite element modelling results are compared with experimental data issued from a double‐notched sample tested with the Arcan fixture at various load ratios. The results show good agreement; the use of the closed‐form solution permitted to predict the failure load more rapidly and in a conservative manner compared with the experimental results. The application of the methodology is also extended to a wider range of joint geometries by means of spatial interpolation using the Kriging model. [ABSTRACT FROM AUTHOR]

Abstract Reactions caused by the diffusion of reactants from different sources can alter rock diffusivity and are therefore the critical mechanisms for evaluating short and long-term behavior of low-permeability rocks used as confinement layers for underground storage, for instance. This paper presents and discusses a set of two diffusion-driven reaction experiments focusing on precipitation of two end-member types of sulfate minerals (gypsum: CaSO 4. 2 H 2 O and barite: BaSO 4) in low-permeability chalk. The time-resolved changes in porosity and effective diffusion coefficient (D e) were evaluated along the duration of the experiments (~140 days), by analyzing the behavior of passive tracers and evaluating the amount of precipitated gypsum or barite from measuring the reactant concentration evolution in the reservoirs at both ends of the sample. Then SEM-EDS and X-ray microtomography (μCT) imaging were used to characterize the initial rock structure and the precipitated materials. Results showed that the change in porosity (from 45% to about 43%) corresponding to the volume of sulfate precipitated, are similar for gypsum and barite. Conversely, the precipitation impact on diffusion properties of the water tracers that were injected 70 days after the beginning of the precipitation step is distinctly different for the each of the studied sulfate mineral. The precipitation of barite generated a more significant impact than gypsum: D e intact = 4.15 × 10−10 m2·s−1 vs. D e barite = 1.1 × 10−10 m2·s−1 and D e gypsum = 2.5 × 10−10 m2·s−1. Post-mortem imaging revealed a thin precipitated zone (~250 μm) in the center of the sample for the barite precipitation experiment, whereas isolated quasi-spherical clusters resulted from the gypsum precipitation. The μCT images at higher resolution showed that the precipitation of barite is heterogeneous at small scale, which explains the HTO diffusion curve. For gypsum, the post mortem imaging around the quasi-spherical clusters showed a significant presence of initial macropores of the connected porosity that were still unfilled. These intact chalk zones allowed HDO to diffuse through the precipitated zone lowering the impact on water tracer diffusivity. These experimental results indicate that the morphology and the distribution of barite precipitates is mainly controlled by homogeneous and heterogeneous nucleation phenomena, whereas gypsum precipitation is mainly controlled by the spatial variability of the initial porous system properties (reactive surface area, tortuosity, pore network structure). Highlights • Diffusion-driven clogging experiments of gypsum and barite were carried out in chalk. • At similar amount of precipitates in chalk, contrasting impact on water tracer diffusivity was observed. • Spatial variability in chalk and intrinsic properties of precipitating mineral controlled the evolution of reacted zone. [ABSTRACT FROM AUTHOR]

Abstract In this paper, we discuss the passivity of coupled different dimensional neural networks. On the one hand, several passivity criteria for the coupled neural networks with different dimensional nodes are proposed by making using of some inequality techniques and Lyapunov functional method. Furthermore, we study the pinning passivity of coupled different dimensional neural networks with fixed and adaptive coupling strength, and obtain some sufficient conditions to ensure the pinning passivity of the considered network by designing proper pinning controllers. On the other hand, the passivity analysis and pinning control problem for coupled different dimensional delayed neural networks are studied similarly. Finally, the effectiveness of the derived results are verified by two numerical examples. [ABSTRACT FROM AUTHOR]

Highlights • An alternative coupling approach for EFEA based on CLFs is presented. • This method is implemented by FEM and the direct wavefield is considered. • This method can be used for structures with strong energy-absorbing ability. Abstract An alternative and improved approach for the analysis of coupled structures in Energy Finite Element Analysis (EFEA) is presented, which is termed as iEFEA in this paper. The conventional EFEA uses the power transfer coefficients (PTCs) to establish the power coupling relation on discontinuous joints, where PTCs are usually derived and processed by the wave transmission approach based on the diffuse wavefield assumption. However, the PTCs in conventional EFEA cannot capture wave filtering effects and only provide accurate predictions when the damping effect is weak. Inspired by the power coupling concept of Statistical Energy Analysis (SEA), an alternative approach using the coupling loss factors (CLFs) and considering the direct wavefield is developed. The present approach is implemented by Finite Element Method (FEM), and thus it inherits the advantages of FEM on handling geometrical complexity and material complexity. The applications of the present approach on coupled beams and coupled plates are demonstrated. The validation simulations show the accuracy and reliability of the present approach. [ABSTRACT FROM AUTHOR]

We study the peculiarities of the solitary state appearance in the ensemble of nonlocally coupled chaotic maps. We show that the nonlocal coupling and features of the partial elements lead to the emergence of multistability in the system. The existence of solitary state is caused by the formation of two attracting sets with different basins of attraction. Their evolution is analyzed depending on the coupling parameters. [ABSTRACT FROM AUTHOR]

Highlights • The proposed method features with the second-order accuracy, adjustable dissipation, and same stability limit but higher accuracy compared to CDM. • Only vector operations are required in the analysis for the problem with lumped mass and arbitrary damping matrics. • Coupled multiple-spring-systems can be decoupled to independent multiple subsystems by using the proposed method. • The simplification and efficiency in the calculation for the coupled system are presented by using the proposed method. • Accurate results for the nonlinear problems can be obtained by using the proposed method. Abstract In this paper, a novel explicit method for decoupling coupled multi-spring systems in the structural dynamic analysis is proposed by ensuring the second-order accuracy in the low-frequency domain. Two parameters μ and β are introduced in this method to flexibly adjust the stability and accuracy properties and suppress the high-frequency spurious vibrations in the solution. Firstly, the standard formulations of this method are derived and its stability and accuracy are analyzed through comparisons with other available state-of-the-art explicit methods in the literature. Then, the performance of this proposed method is specifically evaluated in terms of accuracy, dissipation in the high-frequency domain and computational efficiency, and effectiveness in dealing with nonlinearity through three examples. Finally, a vertical coupled multi-spring system, a train-rail-sleeper-ballast-bridge system, is employed to demonstrate the efficiency and decoupling properties of the proposed method. The presented attractive performance of this method illustrates its advantages in engineering applications. [ABSTRACT FROM AUTHOR]

A mathematical model of a network of nearest neighbor gap-junction coupled neurons has been used to examine the impact of neuronal heterogeneity on the networks' activity during increasing coupling strength. Heterogeneity has been introduced by Huber-Braun model neurons with randomization of the temperature as a scaling factor. This leads to neurons of an enormous diversity of impulse pattern, including burst discharges, chaotic activity, and two different types of tonic firing—all of them experimentally observed in the peripheral as well as central nervous system. When the network is composed of all these types of neurons, randomly selected, a particular phenomenon can be observed. At a certain coupling strength, the network goes into a completely silent state. Examination of voltage traces and inter-spike intervals of individual neurons suggests that all neurons, irrespective of their original pattern, go through a well-known bifurcation scenario, resembling those of single neurons especially on external current injection. All the originally spontaneously firing neurons can achieve constant membrane potentials at which all intrinsic and gap-junction currents are balanced. With limited diversity, i.e., taking out neurons of specific patterns from the lower and upper temperature range, spontaneous firing can be reinstalled with further increasing coupling strength, especially when the tonic firing regimes are missing. Reinstalled firing develops from slowly increasing subthreshold oscillations leading to tonic firing activity with already fairly well synchronized action potentials, while the subthreshold potentials can still be significantly different. Full in phase synchronization is not achieved. Additional studies are needed elucidating the underlying mechanisms and the conditions under which such particular transitions can appear. [ABSTRACT FROM AUTHOR]

The initial value problem for a coupled nonlinear Schrödinger system with unbounded potential is investigated. In the defocusing case, global well-posedness is obtained. In the focusing case, the existence and stability/instability of standing waves are established. Moreover, global well-posedness is discussed via the potential well method. [ABSTRACT FROM AUTHOR]

In many applications, coupling between thermal and mechanical domains can significantly influence structural dynamics. Analytical approaches to study such problems have previously used assumptions such as a proscribed temperature distribution or one-way coupling to enable assessments. In contrast, time-stepping numerical simulations have captured more detailed aspects of multiphysics interactions at the expense of high computational demands and lack of insight of the underlying physics. To provide a new tool that closes the knowledge gap and broadens potential for analytical techniques, this research formulates and analytically solves a thermomechanical beam model considering a combination of thermal and mechanical excitations that result in extreme nonlinear behaviors. Validated by experimental evidence, the analytical framework facilitates the prediction of the nonlinear dynamics of multi-degree-of-freedom structures exhibiting two-way thermomechanical coupling. The analysis enables the investigation of mechanical and thermomechanical impedance metrics as a means to forecast future nonlinear dynamic behaviors such as extreme bifurcations. For the first time, characteristics of mechanical impedance previously reported to predict the onset of dynamic bifurcations in discrete systems are translated to illuminate the nearness of distributed parameter structures to bifurcations. In addition, fundamental connections are discovered in the thermomechanical evaluations between nonlinear low amplitude dynamics of the postbuckled beam and the energetic snap-through vibration that are otherwise hidden by studying displacement amplitudes alone. [ABSTRACT FROM AUTHOR]

In systems biology, nonhomogeneous dynamic Bayesian networks (NH‐DBNs) have become a popular modeling tool for reconstructing cellular regulatory networks from postgenomic data. In this paper, we focus our attention on NH‐DBNs that are based on Bayesian piecewise linear regression models. The new NH‐DBN model, proposed here, is a generalization of an earlier proposed model with sequentially coupled network interaction parameters. Unlike the original model, our novel model possesses segment‐specific coupling parameters, so that the coupling strengths between parameters can vary over time. Thereby, to avoid model overflexibility and to allow for some information exchange among time segments, we globally couple the segment‐specific coupling (strength) parameters by a hyperprior. Our empirical results on synthetic and on real biological network data show that the new model yields better network reconstruction accuracies than the original model. [ABSTRACT FROM AUTHOR]

A coupled thermo-mechanical bond-based peridynamical (TM-BB-PD) method is developed to simulate thermal cracking processes in rocks. The coupled thermo-mechanical model consists of two parts. In the first part, temperature distribution of the system is modeled based on the heat conduction equation. In the second part, the mechanical deformation caused by temperature change is calculated to investigate thermal fracture problems. The multi-rate explicit time integration scheme is proposed to overcome the multi-scale time problem in coupled thermo-mechanical systems. Two benchmark examples, i.e., steady-state heat conduction and transient heat conduction with deformation problem, are performed to illustrate the correctness and accuracy of the proposed coupled numerical method in dealing with thermo-mechanical problems. Moreover, two kinds of numerical convergence for peridynamics, i.e., m- and δ-convergences, are tested. The thermal cracking behaviors in rocks are also investigated using the proposed coupled numerical method. The present numerical results are in good agreement with the previous numerical and experimental data. Effects of PD material point distributions and nonlocal ratios on thermal cracking patterns are also studied. It can be found from the numerical results that thermal crack growth paths do not increases with changes of PD material point spacing when the nonlocal ratio is larger than 4. The present numerical results also indicate that thermal crack growth paths are slightly affected by the arrangements of PD material points. Moreover, influences of thermal expansion coefficients and inhomogeneous properties on thermal cracking patterns are investigated, and the corresponding thermal fracture mechanism is analyzed in simulations. Finally, a LdB granite specimen with a borehole in the heated experiment is taken as an application example to examine applicability and usefulness of the proposed numerical method. Numerical results are in good agreement with the previous experimental and numerical results. Meanwhile, it can be found from the numerical results that the coupled TM-BB-PD has the capacity to capture phenomena of temperature jumps across cracks, which cannot be captured in the previous numerical simulations. [ABSTRACT FROM AUTHOR]

To address security issues in oilwell drillstring system, the drilling operation handling which is in generally not autonomous but ensured by an operator may be drill bit destructive or fatal for the machine. To control of stick-slip phenomenon, the drillstring control at the right speed taking only the drillstring vibration is not sufficient as the mud dynamics and the pressure change around the drill pipes cannot be neglected. A coupled torsional vibration and pressure model is presented, and the well-posedness problem is addressed. As a Partial Differential Equation-Ordinary Differential Equation (PDE-ODE) coupled system, and in order to maintain a non destructive downhole pressure, we investigate the control stability with and without the damping term in the wave PDE. In terms of, the torsional variable, the downhole pressure, and the annulus pressure, the coupled system equilibrium is shown to be exponentially stable. [ABSTRACT FROM AUTHOR]

We apply the homotopy perturbation Sumudu transform method (HPSTM) to the time-space fractional coupled systems in the sense of Riemann-Liouville fractional integral and Caputo derivative. The HPSTM is a combination of Sumudu transform and homotopy perturbation method, which can be easily handled with nonlinear coupled system. We apply the method to the coupled Burgers system, the coupled KdV system, the generalized Hirota-Satsuma coupled KdV system, the coupled WBK system, and the coupled shallow water system. The simplicity and validity of the method can be shown by the applications and the numerical results. [ABSTRACT FROM AUTHOR]

This paper focuses on the input-to-state stability for a general class of stochastic multi-group models with multi-dispersal. By incorporating graph theory with Lyapunov method as well as stochastic analysis techniques, novel sufficient criteria are derived, which are in the form of Lyapunov-type theorem and coefficient-type criterion, respectively. Moreover, to show the applicability of our findings, we employ coefficient-type criterion to analyze the input-to-state stability for stochastic coupled oscillators. Finally, a numerical example and its simulations are offered to demonstrate the validity and feasibility of the theoretic results. [ABSTRACT FROM PUBLISHER]

Traditional Velocity Prediction Programs (VPPs) for sailing yachts rely on empirical relations, while modern techniques include CFD. Normally a multi-dimensional matrix of CFD results is pre-computed and forces and moments obtained by interpolation during a VPP execution. A more exact technique is to use the CFD code itself as a VPP, i.e. to simultaneously integrate the flow and rigid body equations in time. In the present paper a technique of this coupled type is introduced. An initial guess is required for speed and attitude, and by time integration in six degrees of freedom this guess is corrected to a steady state solution. Three phases are identified. First the attitude is kept constant over a period of time to stabilize the flow. Thereafter the different degrees of freedom are released successively and the rudder activated to achieve yaw balance. Finally, in the converged phase, the net forces and moments are zero in all degrees of freedom and the results reported. The performance prediction is carried out for a dinghy and a large high-performance racing yacht. Convergence of all variables is demonstrated and the results used for finding the optimum speed to windward and downwind. Details of the numerical setup are reported. [ABSTRACT FROM AUTHOR]

An interval reduced basis approach (IRBA) is presented for analyzing acoustic response of coupled structural-acoustic system with interval parameters. Simultaneously an integrated framework based on IRBA is established to deal with uncertain acoustic propagation using deterministic finite element (FE) software. The present IRBA aims to improve the accuracy of the conventional first-order approximation and also allow the efficient calculation of second-order approximation of acoustic response. In IRBA, acoustic response is approximated using a linear combination of interval basis vectors with undetermined coefficients. To get explicit expression of acoustic response in terms of interval parameters, the three terms of the second-order perturbation method are employed as basis vectors, and the variant of the Galerkin scheme is applied for derivation of the reduced-order system of equations. For the second-order approximation, the determination of acoustic response interval is reformulated into a series of quadratic programming problems, which are solved using the difference of convex functions (DC) algorithm effectively. The performance of IRBA and availability of the present framework are validated by numerical examples. [ABSTRACT FROM AUTHOR]

An important procedure in transfer path analysis (TPA) is to measure the frequency response functions (FRFs) of the decoupled passive subsystem. The classical TPA method obtains the passive subsystem's FRFs by direct measuring when the system is disassembled. The main shortcoming of the classical method to measure the FRFs is that it is time-consuming due to the necessity to dismount the active part. In this paper, a novel method is proposed to estimate the passive subsystem' FRF matrix without disassembling the coupled mechanical structure. The key idea of this method is that the effect of a coupled subsystem will be canceled out if the links which connect this subsystem with the other one have no deformation, since the coupled systems influence each other only through the links which can be regarded as combinations of connecting springs and dampers. Following this idea, the expression of the passive subsystem's FRF matrix can be deduced from the entire system's FRF matrix directly. The proposed method in this paper is called the virtual decoupling method, since the decoupling is not 'real' but 'virtual'. Obviously, the actual decoupling procedure is avoided so that the shortcoming mentioned above is overcome. The method is validated by a numerical model and a finite element model. [ABSTRACT FROM AUTHOR]

Towards at the active radial magnetic bearing with tightly-coupled redundant supporting structure, we propose a kind of fault-tolerant control strategy to make the remaining structures, under the failures of some electromagnetic actuators, reconfigured by compensating the magnetic flux loss to provide expected supporting force continually. By using FSS (fault status series) to describe the fault status of actuators, an index rule of the current distribution scheme has been designed to resolve different failure conditions of actuators. Fault-tolerant control model has been established to verify the electromagnetic force generation in tightly-coupled redundant supporting structures after failure of actuators. The influence characteristic and mechanism of the bias current coefficient to electromagnetic force generation have been analyzed. The application example shows that fault-tolerant control strategy discussed can restrain the influence of the disturbing force to stabilize the rotor even under the failures of some actuators. In addition, inappropriate selection of the bias current coefficient will be easy to cause electromagnetic force limited by saturation constraint, and unable to provide the desired supporting force, which leads to rotor drop. Improving the real-time performance will effectively reduce the rotor jitter in the reconfiguration of redundant structure discussed. [ABSTRACT FROM AUTHOR]

In this article, a novel miniaturized dual-polarized linear wideband phased array (1 × 16) that operated from 0.45 to 2.5 GHz (5.5:1) is introduced. Although the design of the proposed array is based on the tightly coupled dipoles arrays (TCDA) concept, the proposed array is more difficult to design than the traditional TCDA. Conventionally, the dual-polarized TCDA is usually shown as a square or rectangle planar array for pursuing good performance by using the couplings between the elements. However, to a linear dual-polarized TCDA, only one element is set in the direction of the vertical polarization (V-polarization) or horizontal polarization (H-polarization). No periodicity and no couplings between the elements can be utilized to keep the performance of wide bandwidth. In order to solve this problem and keep the performance in this polarization, the shapes of the element and the ground are designed carefully. The proposed array is designed as a linear array, in which there are 16 unit cells and each unit cell consists of only one horizontal polarized (H-polarized) element and one V-polarized element (1 × 1). The array achieves a low total profile (0.13λlow). The array exhibits a measured active VSWR < 3.0 at broadside and VSWR < 3.3 at = 45° in the azimuth plane. Agreement with simulations presented in this article reveals the feasibility of the design. [ABSTRACT FROM AUTHOR]

This analysis shows the dynamics of a hyperchaotic system changes from its original state to a synchronized state with nonlinear controller. The decreasing complexity of the coupled systems also quantifies the loss of information from its original state to the synchronized state. We proposed and modified a chaos synchronization based secure communication scheme to implement in case of non synchronization. The scheme is designed and illustrated using examples and simulations. Security analysis of the proposed scheme is also investigated. This analysis gives a new direction on chaos based cryptography in case of the coupled systems completely in non synchronized state. [ABSTRACT FROM AUTHOR]

In this paper we present an influence of discontinuous coupling on the dynamics of multistable systems. Our model consists of two periodically forced oscillators that can interact via soft impacts. The controlling parameters are the distance between the oscillators and the difference in the phase of the harmonic excitation. When the distance is large two systems do not collide and a number of different possible solutions can be observed in both of them. When decreasing of the distance, one can observe some transient impacts and then the systems settle down on non-impacting attractor. It is shown that with the properly chosen distance and difference in the phase of the harmonic excitation, the number of possible solutions of the coupled systems can be reduced. The proposed method is robust and applicable in many different systems. [ABSTRACT FROM AUTHOR]

In this article, the Signal Integrity performance analysis of mutual coupling reduction with defective ground structures (DGS) in high speed PCBs has been investigated. The performances of these structures are analyzed, in terms of Time domain, Error Vector Magnitude (EVM), eye pattern and timing jitter. A NRZ test signal with Quadrature Phase Shift keying modulation, with a carrier frequency of 3.5 GHz is used for the EVM measurements. From the EVM measurements, it is observed that the PCB with Circular DGS has the lowest EVM of 1.195 % rms compared to other techniques. Further, the eye pattern and jitter analysis show that the circular DGS has the lowest jitter value of 8 ps at 1Gbps data rate. Finally, the electromagnetic compatibility of proposed method is checked with the surface current distribution and radiated emission analysis. These investigations show that the adoption of the circular DGS in the high speed PCB design, reduces the spacing between two traces without degrading the signal quality. [ABSTRACT FROM AUTHOR]

In this paper, we address the mixed H2/ H ∞ synchronization control for the coupled partial differential systems. First, we introduce the synchronization error dynamics and transform the problem of mixed H2/ H ∞ synchronization control of coupled partial differential systems into the problem of mixed H2/ H ∞ stabilization of the synchronization error dynamics. Then, both the finite and infinite horizon cases for the mixed H2/ H ∞ synchronization control are considered. Sufficient conditions guaranteeing the existence of the solutions to the mixed H2/ H ∞ synchronization control problem are given via a standard completing square technique. When the states of the synchronization error systems are unavailable, the Lunberger observer is designed, and the observer-based mixed H2/ H ∞ synchronization problem is investigated. Based on the solutions to the coupled differential Riccati equations, the optimal control for the observer-based mixed H2/ H ∞ synchronization control is presented. One more time, both the finite and infinite horizon cases are studied under the observer situation. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

This paper is concerned with finite-time synchronization in an array of coupled neural networks with discontinuous activation functions, Markovian jumping parameters, as well as discrete and infinite-time distributed delays (mixed delays) under the framework of Filippov solution. Based on novel Lyapunov-Krasovskii functionals and analytical techniques and M-matrix method, the difficulties caused by the uncertainties of Filippov solutions, time delays, as well as Markov chain are overcome. Several sufficient conditions are obtained to guarantee the synchronization in finite time. Different from existing results on finite-time synchronization of non-delayed systems, the settling time for time-delay systems is dependent not only on the values of the error state at time zero, but also on the histories of the error state, the time delays, and the initial value of Markov chain. Moreover, finite-time synchronization of the coupled neural networks with nonidentical uncertain perturbations is also considered. The obtained results are also applicable to continuous nonlinear systems, which essentially extend existing results which can only finite-timely synchronize or stabilize non-delayed systems. Finally, numerical examples are given demonstrate the effectiveness of the theoretical results. [ABSTRACT FROM AUTHOR]

For thin elastic structures submerged in heavy fluid, e.g., water, a strong interaction between the structural domain and the fluid domain occurs and significantly alters the eigenfrequencies. Therefore, the eigenanalysis of the fluid-structure interaction system is necessary. In this paper, a coupled finite element and boundary element (FE-BE) method is developed for the numerical eigenanalysis of the fluid-structure interaction problems. The structure is modeled by the finite element method. The compressibility of the fluid is taken into consideration, and hence the Helmholtz equation is employed as the governing equation and solved by the boundary element method (BEM). The resulting nonlinear eigenvalue problem is converted into a small linear one by applying a contour integral method. Adequate modifications are suggested to improve the efficiency of the contour integral method and avoid missing the eigenvalues of interest. The Burton-Miller formulation is applied to tackle the fictitious eigenfrequency problem of the BEM, and the optimal choice of its coupling parameter is investigated for the coupled FE-BE method. Numerical examples are given and discussed to demonstrate the effectiveness and accuracy of the developed FE-BE method. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

High-temperature tensile testing of AH36 material in a wide range of temperatures (1173-1573 K) and strain rates (10-4-10-2 s-1) has been obtained by using a Gleeble system. These experimental stress-strain data have been adopted to develop the constitutive equation. The constitutive equation of AH36 material was suggested based on the modified Arrhenius-type equation and the modified Rossard equation respectively. The results indicate that the constitutive equation is strongly influenced by temperature and strain, especially strain. Moreover, there is a good agreement between the predicted data of the modified Arrhenius-type equation and the experimental results when the strain is greater than 0.02. There is also good agreement between the predicted data of the Rossard equation and the experimental results when the strain is less than 0.02. Therefore, a coupled equation where the modified Arrhenius-type equation and Rossard equation are combined has been proposed to describe the constitutive equation of AH36 material according to the different strain values in order to improve the accuracy. The correlation coefficient between the computed and experimental flow stress data was 0.998. The minimum value of the average absolute relative error shows the high accuracy of the coupled equation compared with the two modified equations. [ABSTRACT FROM AUTHOR]

We propose a simple criterion for revealing the breaking of pair interaction symmetry in strongly coupled dissipative systems. The criterion is based on the analysis of correlations between the velocities of strongly interacting particles, which can be measured relatively easily in experiments with macroparticles in various media. We derive analytic relations that make it possible to calculate the derivatives of the interaction force between a pair of particles from the data on the correlations of their velocities and coordinates. The proposed criterion and relations are verified using the results of numerical simulation of the dynamics of dust particles in a plasma. [ABSTRACT FROM AUTHOR]

Synchronization in the optical systems coupled network always suffers from bubbling events. In this paper, we numerically investigate the statistical properties of the synchronization characteristics and bubbling effects in the electro-optic delayed feedback oscillator coupled network with different coupling strength, delay time and gain coefficient. Furthermore, we compare our results with the synchronization properties of semiconductor laser (SL) coupled network, which indicates that the electro-optic delayed feedback oscillator can be better to suppress the bubbling effects in the synchronization of coupled network under the same conditions. [ABSTRACT FROM AUTHOR]

In this proceeding paper, we briefly discuss some holographic models without translational invariance. We construct holographic models which possess the linear temperature resistivity and various anomalous transports consistent with the cuprate strange metal. We also compute the fermion spectral function in the context of holographic massive gravity which is argued to correspond to the system without translational invariance. Our fermion spectral function calculations provide supporting evidences on the interpretation of holographic massive gravity as a disordered system. [ABSTRACT FROM AUTHOR]

The suppression of oscillations in coupled systems may lead to several unwanted situations, which requires a suitable treatment to overcome the suppression. In this paper, we show that the environmental coupling in the presence of direct interaction, which can suppress oscillation even in a network of identical oscillators, can be modified by introducing a feedback factor in the coupling scheme in order to restore the oscillation. We inspect how the introduction of the feedback factor helps to resurrect oscillation from various kinds of death states. We numerically verify the resurrection of oscillations for two paradigmatic limit cycle systems, namely Landau–Stuart and Van der Pol oscillators and also in generic chaotic Lorenz oscillator. We also study the effect of parameter mismatch in the process of restoring oscillation for coupled oscillators. [ABSTRACT FROM AUTHOR]

This work analyses the propagation of soliton beam in parity–time () symmetric nonlinear coupled systems with varying loss/gain profiles. When the loss/gain coefficient is a constant, the phase transition takes place when it is equal to twice the coupling constant and the beam propagation is unstable above the phase transition point. When the loss/gain profiles are varying with the propagation distance, the phase transition point also changes. The linear, quadratic and exponential profiles have been chosen for the loss/gain coefficient. Phase transition point increases when the loss/gain profile is an exponential function of propagation distance and decreases when it is a linear or quadratic function. [ABSTRACT FROM AUTHOR]

Structural noise is an important factor that endangers aircraft fatigue life and flight safety. It also has a negative effect on aircraft stealth performance and noise navigability. An optimal design of a structure-acoustic coupled system is an effective way to reduce noise and vibration. Due to the uncertainties that exist in the structural and acoustical parameters, the traditional deterministic optimization method may be unfeasible when the parameters are subject to fluctuations. This means that when the parameters are uncertain, the results obtained from the deterministic optimization method may be beyond their constraints. This paper proposes to apply the stochastic reliability-based optimization method to the design optimization of the coupled structural-acoustic system with random parameters. A comparison between the results of the stochastic reliability-based method, the safety factor-based method, and the deterministic method show that the first two methods can effectively consider the dispersion of the parameters. [ABSTRACT FROM AUTHOR]

This paper studies the bipartite synchronization in a network of nonlinear systems with antagonistic interactions and switching topologies. In order to obtain some conditions such that the network achieves bipartite synchronization for any initial conditions, we design a pinning scheme to pin a part of agents. Under the assumptions that all signed graphs are structurally balanced and the nonlinear system satisfies a one-sided Lipschitz condition, we derive conditions under which the network reaches bipartite synchronization for any initial conditions and arbitrary switching signals. For a general switching signal (especially the periodic switching signal), some conditions related to switching signal are obtained. Finally, we present two numerical examples to illustrate the effectiveness of the obtained results. [ABSTRACT FROM AUTHOR]

This paper is concerned with free vibration analysis of plate/shell coupled structures with two opposite edges simply supported by the method of reverberation-ray matrix. The equations of motion of the flat plate and the open circular cylindrical shell, respectively based on the classical thin plate theory and the Flügge thin shell theory, are introduced. Analytical solutions of the combination of a traveling wave form along the circumferential direction and a standing wave form along the axial direction are obtained. The method of reverberation-ray matrix is applied to derive the equation of the natural frequencies for the plate/shell coupled structures. The semi-analytical natural frequencies are obtained with the employment of the golden section search algorithm. The semi-analytical calculation results of three typical plate/shell coupled structures are presented and the results are compared with those obtained by the finite element method. The comparison shows that the calculation results obtained in this paper are of high accuracy and that the formulation presented in this manuscript are validated for free vibration analysis of plate/shell coupled structures. [ABSTRACT FROM AUTHOR]

A $3\times3$ parasitically coupled microstrip patch array antenna is proposed in this communication. The array consists of nine microstrip patches. The center patch fed by a probe works as a driven element while the other eight surrounding patches are parasitic elements. Four microstrip lines located between elements are employed as feed network to distribute coupled energy in both the E- and H-planes of the array. Thus, the $3\times3$ elements can be arranged on a single-layered substrate and excited simultaneously. The antenna has a simplified feed structure and a compact size. Meanwhile, the experimental results show that the proposed antenna has a broad bandwidth of 15.4% from 18 to 21 GHz and a maximum gain of 14.8 dBi. [ABSTRACT FROM PUBLISHER]

The main objective of this paper is to propose a tensor product model transformation based decoupled terminal sliding mode controller design methodology. The methodology is divided into two steps. In the first step, tensor product model transformation is applied to the single-input-multi-output system and a parameter-varying weighted linear time-invariant system is obtained. Then, decoupled terminal sliding mode controller is designed based on the linear time-invariant systems. The main novelty of this paper is that the nonsingular terminal sliding mode control design is based on a numerical model rather than an analytical one. Finally, simulations are tested on cart-pole system and translational oscillations with a rotational actuator system. [ABSTRACT FROM AUTHOR]

This paper proposes a novel integrated navigation filter based on a combined long baseline/ultra short baseline acoustic positioning system with application to underwater vehicles. With a tightly coupled structure, the position, linear velocity, attitude, and rate gyro bias are estimated, considering the full nonlinear system dynamics without resorting to any algebraic inversion or linearisation techniques. The resulting solution ensures convergence of the estimation error to zero for all initial conditions, exponentially fast. Finally, it is shown, under simulation environment, that the filter achieves very good performance in the presence of sensor noise. [ABSTRACT FROM AUTHOR]

The paper proposes an innovative estimation and control scheme that enables the distributed monitoring and control of large-scale processes. The proposed approach considers a discrete linear time-invariant process controlled by a network of agents that may both collect information about the evolution of the plant and apply control actions to drive its behaviour. The problem makes full sense when local observability/controllability is not assumed and the communication between agents can be exploited to reach system-wide goals. Additionally, to reduce agents bandwidth requirements and power consumption, an event-based communication policy is studied. The design procedure guarantees system stability, allowing the designer to trade-off performance, control effort and communication requirements. The obtained controllers and observers are implemented in a fully distributed fashion. To illustrate the performance of the proposed technique, experimental results on a quadruple-tank process are provided. [ABSTRACT FROM AUTHOR]