State Vector Method Research Articles

Manipulation of acoustic wave scattering from cylindrical shells using a coating of FG magneto-electro-elastic composite materials: Active acoustic cloaking

Acoustically cloaking an object from view of a system that uses acoustic waves for detection is an attractive and practical capability. The aim of the current investigation is to hide a steel cylinder containing axial flow acoustically, which is achieved through the application of a coating of FG electro-magnetic material. This coating is employed to minimize the sound pressure that is scattered from the structure, and it comprises piezoelectric (BaTiO3) and magnetostrictive (CoFe2O4) make up the coating. Accordingly, the method presented is based on optimal control and incorporates an improved particle swarming optimization algorithm. The decision variables are the magnetic and electrical potentials on the inner and outer surfaces of the coating, whereas the cost function is the scattered acoustic pressure. In other words, what are the values of electrical and magnetic potentials on the inner and outer surfaces of the coating to minimize the scattered pressure? Subsequently, by defining the electrical and magnetic boundary conditions in a certain way, it is feasible to achieve the complete cancelation of scattered sound pressure. The governing equation of each layer is extracted using an orthotropic laminate composite model that is based on the 3-D theory of elasticity. A state-vector method is then applied to obtain the propagator matrix that links the state variables at each layer's surfaces. The results show that the proposed acoustic cloaking technique has an excellent capability for hiding the shell immersed in the fluid.

Sound Propagation of Three-Dimensional Sandwich Panels: Influence of Three-Dimensional Re-Entrant Auxetic Core

Re-entrant auxetic cellular structures (RACSs) offer various mechanical properties. Specifically, their high acoustic absorption and dissipation properties turn them into proper candidates to effectively increase the sound insulation characteristics of sandwich plates. Accordingly, this approach proposes an analytical strategy to investigate the exact effect of using three-dimensional (3D)-RACS in order to determine the sound transmission loss (STL) coefficient of a sandwich panel. Therefore, the dynamic equations of fluid–structure interaction are extracted using 3D stress distribution, and then the obtained equations are solved analytically based on the state vector method. The reliability and precision of the outcomes are checked according to previous works. The results obtained are significant because the designed sandwich model seems to improve the sound characteristics of the system based on the STL comparisons between the current approach and the single-layer plates as well as sandwich panels with other core geometries. The achievements of this study can provide novel insights into the STL of 3D-RACS sandwich systems with a complex core model.

Numerical Modeling of a Propagation Process Using (Mpdx) Matrix Associated to Second Order Partial Diferential Equations with Two Independent Variables

Abstract This paper presents a preliminary version of case study for propagation process using Matrix of Partial Derivatives of the State Vector (Mpdx) Method associated to second order Partial Differential Equations with two Independent Variables and Approximating Solutions. Considering a thermally insulated layer of a specific thickness exposed on the upper part to a constant overtemperature with a uniform distribution over the entire heat transfer surface, using numerical modeling are emphasized some interpretation variants for evolution of processed signals for possible applications.

Graph representations for the analysis of multi-agent spatiotemporal sports data

Analyzing tactical patterns in invasion games using multi-agent spatiotemporal data is a challenging task at the intersection of computer and sports science. A fundamental yet understudied problem in this area is finding an optimal data representation for processing athlete trajectories using machine learning algorithms. In the present work, we address this gap by discussing common representations in use and propose Tactical Graphs, an alternative graph-based format capable of producing integrative, contextualized models for machine learning applications. We provide an in-depth, domain-specific motivation of the proposed data representation scheme and show how this approach exploits inherent data traits. We propose Tactical Graph Networks (TGNets), a light-weight, hybrid machine learning architecture sensitive to player interactions. Our method is evaluated with an extensive ablation study and the first comprehensive state of the art comparison between standard feature, state vector, and image-based methods on the same dataset. Experiments were conducted using real-world football data containing short sequences of defensive play labelled according to the outcome of ball winning attempts. The results indicate that TGNets are on par with state-of-the-art deep learning models while exhibiting only a fraction of their complexity. We further demonstrate that selecting the right data representation is crucial as it has a significant influence on model performance. The theoretical findings and the proposed method provide insights and a strong methodological alternative for all classification, prediction or pattern recognition applications in the areas of collective movement analysis, automated match analysis, and performance analysis.

A Livelihood Resilience Measurement Framework for Dam-Induced Displacement and Resettlement

The concepts of resilience and livelihood resilience are growing in prominence with water resource development that aims to measure and build resilience to specific disturbances and shocks. However, practical frameworks to measure livelihood resilience are needed, not just a theoretical framework. In this paper, we introduce the livelihood resilience measurement (LRM) framework, which draws on Hooke’s law; use the state vector method to calculate livelihood resilience scores; and test the effectiveness of the method by correlation analysis. We illustrate the framework by using it to measure livelihood resilience in Henan Province, China, and assess the strategies that build livelihood resilience. The advantages and limitations of the framework are explored and discussed by drawing on empirical examples. Besides illustrating how to apply the LRM framework in a practical case, we discuss how to communicate with stakeholders to identify and strengthen the factors that build resilience. In this study, land ownership, housing and property value, and emergency cost are the most significant of these factors. Thus, the LRM framework has the potential to help reservoir-affected families protect their livelihood capital and to help governments improve social welfare. It can thus serve as a tool for monitoring and improving the effectiveness of policies and practices aimed at building livelihood resilience.

Free vibration analysis of rotating thin-walled cylindrical shells with hard coating based on Rayleigh-Ritz method

This paper focuses on the free vibration analyses of the rotating hard-coating cylindrical shells with various boundary conditions and the effects of hard coating on the vibration behaviors of the rotating shells. To accurately predict more natural characteristics, the characteristic orthogonal polynomials are taken as the admissible displacement functions. Considering the influences of Coriolis force, centrifugal force and initial hoop tension caused by rotation, the equations of motion of the shells are established by the use of the Rayleigh-Ritz method. Based on the state vector method, an efficient method is developed to solve the equations. By comparing with the results of both the finite element analysis and published literatures, the high accuracy and good convergence of the proposed model are verified. In addition, the effects of the boundary conditions, parameters of hard coating, rotating speed and number of circumferential waves on the vibration behaviors of the hard-coating shells are evaluated. This study may provide a reference for the application of hard-coating damping treatment to the vibration suppression of rotating thin-walled structures.

On the dispersion of cylinder guided waves propagating in a multilayer composite hollow cylinder made of anisotropic materials

The formula system of the state-vector and Legendre polynomials hybrid method (SV-LPHM) was applied to produce the dispersion curves and mode shape for the general anisotropic multilayer composite cylinders with whatever the dissimilarities of the layer material properties. According to relevant literature's reports, traditional Legendre polynomial method was only able to deal with the multilayer system where the material properties of adjacent layers are not significantly changed. To overcome the drawback, we introduce the state vector method to reshape the wave equation, boundary conditions and interface continuous conditions of the multilayer hollow cylinder in a consistent manner. Moreover, expanding the displacement field by the Legendre polynomials, and then a complete and concise state matrix form is formed for dispersion equation after complex algebraic transformation. All the matrices involving the mass and stiffness have been deduced analytically by the recurrence relation and orthogonality of the Legendre polynomial. The abovementioned operation overcomes the cumbersome when applying traditional Legendre polynomial method to dealing with the interface displacement and stress continuity. Firstly, we outlined the derivation of the formalism of the hybrid method (SV-LPHM) for guided waves propagating in the anisotropic multilayer hollow cylinder with an arbitrary number of layers. And then we demonstrated the SV-LPHM technique on the composite pipe of isotropic material and anisotropic material, where the key-factors of phase speed, displacement, and stress distribution were assessed and elaborated thoroughly. The results confirm the exponential convergence of the SV-LPHM compared with finite element methods.

Three-dimensional static analysis of multilayered one-dimensional orthorhombic quasicrystal spherical shells with the piezoelectric effect

The static analysis of multilayered one-dimensional orthorhombic piezoelectric quasicrystals spherical shells is presented by using the state vector method. Based on two separated state equations, the solution of a homogenous spherical shell is derived, and the solution for the corresponding multilayered case is obtained via the propagator matrix method. Mechanical behaviors of spherical shells subjected to two kinds of symmetric loads are analyzed, respectively. Under uniformed loads, smaller phonon displacements are achieved in a quasicrystal-skin structure than those in crystal-skin one. Under the compression of rigid half-plane, the radius of the circular contact area increases with decreasing thickness of quasicrystal layers.

An Ensemble Approach for Improved Short-to-Intermediate-Term Seismic Potential Evaluation

Pattern informatics (PI), load/unload response ratio (LURR), state vector (SV), and accelerating moment release (AMR) are four previously unrelated subjects, which are sensitive, in varying ways, to the earthquake’s source. Previous studies have indicated that the spatial extent of the stress perturbation caused by an earthquake scales with the moment of the event, allowing us to combine these methods for seismic hazard evaluation. The longrange earthquake forecasting method PI is applied to search for the seismic hotspots and identify the areas where large earthquake could be expected. And the LURR and SV methods are adopted to assess short-to-intermediate-term seismic potential in each of the critical regions derived from the PI hotspots, while the AMR method is used to provide us with asymptotic estimates of time and magnitude of the potential earthquakes. This new approach, by combining the LURR, SV and AMR methods with the choice of identified area of PI hotspots, is devised to augment current techniques for seismic hazard estimation. Using the approach, we tested the strong earthquakes occurred in Yunnan–Sichuan region, China between January 1, 2013 and December 31, 2014. We found that most of the large earthquakes, especially the earthquakes with magnitude greater than 6.0 occurred in the seismic hazard regions predicted. Similar results have been obtained in the prediction of annual earthquake tendency in Chinese mainland in 2014 and 2015. The studies evidenced that the ensemble approach could be a useful tool to detect short-to-intermediate-term precursory information of future large earthquakes.

Development of a Combination Approach for Seismic Hazard Evaluation

We developed a synth esis approach to augment current techniques for seismic hazard evaluation by combining four previously unrelated subjects: the pattern informatics (PI), load/unload response ratio (LURR), state vector (SV), and accelerating moment release (AMR) methods. Since the PI is proposed in the premise that the change in the seismicity rate is a proxy for the change in the tectonic stress, this method is used to quantify localized changes surrounding the epicenters of large earthquakes to objectively quantify the anomalous areas (hot spots) of the upcoming events. On the short-to-intermediate-term estimation, we apply the LURR, SV, and AMR methods to examine the hazard regions derived from the PI hot spots. A predictive study of the 2014 earthquake tendency in Chinese mainland, using the seismic data from 1970-01-01 to 2014-10-01, shows that, during Jan 01 to Oct 31, 2014, most of the M > 5.0 earthquakes, especially the Feb 12 M7.3 Yutian, May 30 M6.1 Yingjiang, Aug. 03 M6.5 Ludian, and Oct 07 M6.6 earthquakes, occurred in the seismic hazard regions predicted. Comparing the predictions produced by the PI and combination approaches, it is clear that, by using the combination approach, we can screen out the false-alarm regions from the PI estimation, without reducing the hit rate, and therefore effectively augment the predictive power of current techniques. This provided evidence that the multi-method combination approach may be a useful tool to detect precursory information of future large earthquakes.

Input–Output Linearizing Control of the Underactuated Hovercraft Using the Derivative-Free Nonlinear Kalman Filter

The paper proposes a nonlinear control approach for the underactuated hovercraft model based on differential flatness theory and uses a new nonlinear state vector and disturbances estimation method under the name of derivative-free nonlinear Kalman filter. It is proven that the nonlinear model of the hovercraft is a differentially flat one. It is shown that this model cannot be subjected to static feedback linearization, however it admits dynamic feedback linearization which means that the system's state vector is extended by including as additional state variables the control inputs and their derivatives. Next, using the differential flatness properties it is also proven that this model can be subjected to input–output linearization and can be transformed to an equivalent canonical (Brunovsky) form. Based on this latter description the design of a state feedback controller is carried out enabling accurate maneuvering and trajectory tracking. Additional problems that are solved in the design of this feedback control scheme are the estimation of the nonmeasurable state variables in the hovercraft's model and the compensation of modeling uncertainties and external perturbations affecting the vessel. To this end, the application of the derivative-free nonlinear Kalman filter is proposed. This nonlinear filter consists of the Kalman Filter's recursion on the linearized equivalent model of the vessel and of an inverse nonlinear transformation based on the differential flatness features of the system which enables to compute estimates for the state variables of the initial nonlinear model. The redesign of the filter as a disturbance observer makes possible the estimation and compensation of additive perturbation terms affecting the hovercraft's model. The efficiency of the proposed nonlinear control and state estimation scheme is confirmed through simulation experiments.

Multi-Methods Combined Analysis of Future Earthquake Potential

Prior to an earthquake, natural seismicity is correlated across multiple spatial and temporal scales. Many studies have indicated that an earthquake is hard to accurately predict by a single time-dependent precursory method. In this study, we attempt to combine four earthquake prediction methods, i.e. the Pattern Informatics (PI), Load/Unload Response Ratio (LURR), State Vector (SV), and Accelerating Moment Release (AMR) to estimate future earthquake potential. The PI technique is founded on the premise that the change in the seismicity rate is a proxy for the change in the underlying stress. We first use the PI method to quantify localized changes surrounding the epicenters of large earthquakes to objectively quantify the anomalous areas (hot spots) of the upcoming events. Next, we delineate the seismic hazard regions by integrating with regional active fault zones and small earthquake activities. Then, we further evaluate the earthquake potential in the seismic hazard regions using the LURR, SV and AMR methods. Retrospective tests of this new approach on the large earthquakes (M > 6.5) which have occurred in western China over the last 3 years show that the LURR and SV time series usually climb to an anomalously high peak months to years prior to occurrence of a large earthquake. And, the asymptote time, tc, “predicted” by the AMR method correspond to the time of the actual events. The results may suggest that the multi-methods combined approach can be a useful tool to provide stronger constraints on forecasts of the time and location of future large events.

Autler–Townes triplet spectroscopy: An analytical approach

In Ref. [Opt. Commun. 273, 464–472 (2007)] we studied Autler–Townes triplet spectrum. The presented results were not easy to display in readable and transparent form because the operating physical mechanism is hidden by the algebraic complexity. Here we present analytical results in a very simple and interpretable form. These results enable us to get a new insight into the interference mechanism in a quiet clear manner. We have given a new dimension to the problem in calculating the emission spectrum by state vector method. New estimates are given to measure the spectroscopic parameters in analytical fashion. The interference mechanism in the excited three decaying dressed state is effectively explored which splits the single Lorentzian peak to three spectral components due to two dark lines. The width of each spectral component can be narrowed to up to 0.05Γ.

Comparison Between LURR and State Vector Analysis Before Strong Earthquakes in Southern California Since 1980

There are seven strong earthquakes with M ≥ 6.5 that occurred in southern California during the period from 1980 to 2005. In this paper, these earthquakes were studied by the LURR (Load/Unload Response Ratio) method and the State Vector method to detect if there are anomalies before them. The results show that LURR anomalies appeared before 6 earthquakes out of 7 and State Vector anomalies appeared before all 7 earthquakes. For the LURR method, the interval between maximum LURR value and the forthcoming earthquake is 1 to 19 months, and the dominant mean interval is about 10.7 months. For the State Vector method, the interval between the maximum modulus of increment State Vector and the forthcoming earthquake is from 3 to 27 months, but the dominant mean interval between the occurrence time of the maximum State Vector anomaly and the forthcoming earthquake is about 4.7 months. The results also show that the minimum valid space window scale for the LURR and the State Vector is a circle with a radius of 100 km and a square of 3°×3°, respectively. These results imply that the State Vector method is more effective for short-term earthquake prediction than the LURR method, however the LURR method is more effective for location prediction than the State Vector method.

Non-classical correlation of the two emission fields by a four-level atomic ensemble

The normalized second-order correlation of the emission fields from a driven four-level atomic ensemble is investigated theoretically by using the state vector method. The violation of Cauchy-Schwarz inequality, which indicates the establishment of non-classical correlation between two emission fields, has been found. The effects of various decays and time delay on the correlation are discussed in detail, which are helpful in finding the ways to obtain high non-classical correlation. This technique for the generation of non-classical light is operable based on the current experimental technology and will lead to some potential applications in quantum information science.

Steady-State Solutions of Multilayered and Cross-Anisotropic Poroelastic Half-Space due to a Point Sink

This paper presents analytical solutions for the steady-state response of displacements and stresses in a half-space subjected to a point sink. The half-space is modeled as a multilayered poroelastic medium with both the permeability and the poroelasticity being cross anisotropic. The basic governing equations are presented in dimensionless style, and the state vector method together with the Hankel transform technique is adopted to solve them and obtain a transfer matrix in a clearly arranged way. Forward and backward transfer matrix techniques are utilized in the analytical formulation of solutions for a multilayered half space. Numerical results are presented to conduct some parametric studies and illustrate the influence of layering and material inhomogeneity on the settlement of the soils. The numerical evaluations of the solutions in the multilayered porous media can be easily achieved with high efficiency and accuracy.

Consolidation of multilayered half space with anisotropic permeability and compressible constituents

This paper presents analytical solutions of consolidation for poroelastic and multilayered half space, and anisotropy of the permeability and the compressibility of the pore fluid are considered. State vector method together with Laplace–Hankel transform techniques are used to solve the basic governing equations, and obtain the transfer matrix in a clearly arranged way. Forward and backward transfer matrix techniques are utilized in the analytical formulation of solutions for the multilayered half space. A numerical inversion scheme of Crump's method is adopted to obtain time-domain solution. Numerical results are presented for a single homogeneous soil layer and a multilayered half space, and they illustrate the influences of the anisotropy of permeability and the compressibility of the pore fluid on the consolidation of the soils.

The state vector methods for space axisymmetric problems in multilayered piezoelectric media

The state vector equations for space axisymmetric problems of transversely isotropic piezoelectric media are established from the basic equations. Using the Hankel transform, the state vector equations are reduced to a system of ordinary differential equations. An analytical solution of the problems in the Hankel transform space is presented in the form of the product of initial state vector and transfer matrix. The transfer matrices are given for the three distinct eigenvalues. Applications of the solutions are discussed. An analytical solution for the transversely isotropic semi-infinite piezoelectric media subjected to concerted point loads on the surface z=0 is presented in the Hankel transform space. Using transfer matrix and the continuity conditions at the layer interfaces, the general solution formulation of N-layered transversely isotropic piezoelectric media is given. A selected set of numerical solutions is presented for a layered semi-infinite piezoelectric solid.

Applying stack simulation for branch target buffers

Branch target buffer (BTB) is widely used in modern microprocessor designs to reduce the penalties caused by branches. To evaluate the performance of a BTB, trace-driven simulation is often used. However, as the trace of a typical program is very large, the simulation time is often too long. To reduce the simulation time, we developed a stack simulation technique for BTB to evaluate many sets of design parameters in one simulation pass. Due to the fact that the prediction information in the BTB does not have the inclusion property – a property which makes the stack simulation work, we propose a state vector method to enumerate the prediction information for different sets of BTB design parameters to mimic the inclusion property. Simulation results show that the state vector method greatly reduces the simulation time. The speedup of the stack simulation for BTB proposed in this paper over the traditional BTB simulation is 4.68 in terms of simulation time when 13 sets of BTB design parameters are simulated in one simulation pass.

The state vector methods of axisymmetric problems for multilayered anisotropic elastic system

The state vector methods of axisymmetric problems for multilayered anisotropic elastic system