Hybrid Strategy of Partitioned and Monolithic Methods for Solving Strongly Coupled Analysis of Inverse and Direct Piezoelectric and Circuit Coupling

The inverse and direct piezoelectric and circuit coupling are widely observed in advanced electro-mechanical systems such as piezoelectric energy harvesters.Existing strongly coupled analysis methods based on direct numerical modeling for this phenomenon can be classified into partitioned or monolithic formulations.Each formulation has its advantages and disadvantages,and the choice depends on the characteristics of each coupled problem.This study proposes a new option:a coupled analysis strategy that combines the best features of the existing formulations,namely,the hybrid partitioned-monolithic method.The analysis of inverse piezoelectricity and the monolithic analysis of direct piezoelectric and circuit interaction are strongly coupled using a partitioned iterative hierarchical algorithm.In a typical benchmark problem of a piezoelectric energy harvester,this research compares the results from the proposed method to those from the conventional strongly coupled partitioned iterative method,discussing the accuracy,stability,and computational cost.The proposed hybrid concept is effective for coupled multi-physics problems,including various coupling conditions.

Algorithm Selection Method Based on Coupling Strength for Partitioned Analysis of Structure-Piezoelectric-Circuit Coupling

In this study, we propose an algorithm selection method based on coupling strength for the partitioned analysis ofstructure-piezoelectric-circuit coupling, which includes two types of coupling or inverse and direct piezoelectriccoupling and direct piezoelectric and circuit coupling. In the proposed method, implicit and explicit formulationsare used for strong and weak coupling, respectively. Three feasible partitioned algorithms are generated, namely(1) a strongly coupled algorithm that uses a fully implicit formulation for both types of coupling, (2) a weaklycoupled algorithm that uses a fully explicit formulation for both types of coupling, and (3) a partially stronglycoupled and partially weakly coupled algorithm that uses an implicit formulation and an explicit formulation forthe two types of coupling, respectively.Numerical examples using a piezoelectric energy harvester,which is a typicalstructure-piezoelectric-circuit coupling problem, demonstrate that the proposed method selects the most costeffectivealgorithm.

Airgap-harmonic-oriented Partitioned Design Method of PMV Motor with Improved Torque Performances

Here,we introduce a partitioned design method that is oriented toward airgap harmonic for permanent magnet vernier(PMV)motors.The method proposes the utilization of airgap flux harmonics as an effective bridge between the torque design region and the torque performances.To illustrate the efficacy of this method,a partitioned design PMV motor is presented and compared with the initial design.Firstly,the torque design region of the rotor is artfully divided into the torque enhancement region and ripple reduction region.Meanwhile,the main harmonics that generate output torque are chosen and enhanced,optimization.Moreover,the harmonics that generate torque ripple are selected and reduced based on torque harmonics optimization.Finally,the functions of the partitioned PMV motor torque are assessed based on the finite element method.By the purposeful design of these two regions,the output torque is strengthened while torque ripple is inhibited effectively,verifying the effectiveness and reasonability of the proposed design method.

Symplectic partitioned Runge-Kutta method based onthe eighth-order nearly analytic discrete operator and its wavefield simulations

We propose a symplectic partitioned Runge-Kutta （SPRK） method with eighth-order spatial accuracy based on the extended Hamiltonian system of the acoustic waveequation. Known as the eighth-order NSPRK method, this technique uses an eighth-orderaccurate nearly analytic discrete （NAD） operator to discretize high-order spatial differentialoperators and employs a second-order SPRK method to discretize temporal derivatives.The stability criteria and numerical dispersion relations of the eighth-order NSPRK methodare given by a semi-analytical method and are tested by numerical experiments. We alsoshow the differences of the numerical dispersions between the eighth-order NSPRK methodand conventional numerical methods such as the fourth-order NSPRK method, the eighth-order Lax-Wendroff correction （LWC） method and the eighth-order staggered-grid （SG）method. The result shows that the ability of the eighth-order NSPRK method to suppress thenumerical dispersion is obviously superior to that of the conventional numerical methods. Inthe same computational environment, to eliminate visible numerical dispersions, the eighth-order NSPRK is approximately 2.5 times faster than the fourth-order NSPRK and 3.4 timesfaster than the fourth-order SPRK, and the memory requirement is only approximately47.17% of the fourth-order NSPRK method and 49.41% of the fourth-order SPRK method,which indicates the highest computational efficiency. Modeling examples for the two-layermodels such as the heterogeneous and Marmousi models show that the wavefields generatedby the eighth-order NSPRK method are very clear with no visible numerical dispersion.These numerical experiments illustrate that the eighth-order NSPRK method can effectivelysuppress numerical dispersion when coarse grids are adopted. Therefore, this methodcan greatly decrease computer memory requirement and accelerate the forward modelingproductivity. In general, the eighth-order NSPRK method has tremendous potential value forseismic exploration and seismology research.

THE SUPERIORITY OF EMPIRICAL BAYES ESTIMATION OF PARAMETERS IN PARTITIONED NORMAL LINEAR MODEL

In this article,the empirical Bayes（EB）estimators are constructed for the estimable functions of the parameters in partitioned normal linear model.The superiorities of the EB estimators over ordinary least-squares（LS）estimator are investigated under mean square error matrix（MSEM）criterion.

Strong coupling between height of gaps and thickness of thermal boundary layer in partitioned convection system

A direct numerical simulation(DNS) method is used to calculate the partitioned convection system with Ra number ranging from 10^7 to 2×10^9.Using the boundary layer thickness to normalize the height of gaps d, we find a strong consistency between the variation of the TD number(the average value of the temperature in each heat transfer channel is averaged after taking the absolute values) with the change of the height of gaps and the variation of the TD number with the change of Ra number in partitioned convection.For a given thickness of partition, heights of gaps are approximately equal to 0.5 or 1 time of the thermal boundary layer thickness λθ at different Ra numbers.TD number representing temperature characteristics is almost the constant value, which means that TD number is a function of d/λθ only.Analysis of local temperature field of area in gaps shows that the temperature distribution in the gaps are basically the same when d/λθ is certain.The heat transfer Nu number of the system at d/λθ≈ 0.5 is larger than that of d/λθ≈ 1, both of them have the same scaling law with Ra number and Nu^Ra^0.25.

Partitioned Method of Insect Flapping Flight for Maneuvering Analysis

This study proposed a partitioned method to analyze maneuvering of insects during flapping flight.This method decomposed the insect flapping flight into wing and body subsystems and then coupled them via boundary conditions imposed on the wing’s base using one-way coupling.In the wing subsystem,the strong coupling of the flexible wings and surrounding fluid was accurately analyzed using the finite element method to obtain the thrust forces acting on the insect’s body.The resulting thrust forces were passed from the wing subsystem to the body subsystem,and then rigid body motion was analyzed in the body subsystem.The rolling,yawing,and pitching motions were simulated using the proposed method as follows:In the rolling simulation,the difference of the stroke angle between the right and left wings caused a roll torque.In the yawing simulation,the initial feathering angle in the right wing only caused a yaw torque.In the pitching simulation,the difference between the front-and back-stroke angles in both the right and left wings caused a pitch torque.All three torques generated maneuvering motion comparable with that obtained in actual observations of insect flight.These results demonstrate that the proposed method can adequately simulate the fundamental maneuvers of insect flapping flight.In the present simulations,the maneuvering mechanisms were investigated at the governing equation level,which might be difficult using other approaches.Therefore,the proposed method will contribute to revealing the underlying insect flight mechanisms.

Influence of Inner/Outer Stator Pole Ratio and Relative Position on Electromagnetic Performance of Partitioned Stator Switched Flux Permanent Magnet Machines

Based on the 6-pole outer stator(armature winding-stator),the influence of inner(permanent magnet-stator)/outer stator pole ratio n(n=NIS/NOS),stator relative positions and rotor pole number combinations on electromagnetic performance of partitioned stator switched flux permanent magnet(PM)machines(PS-SFPMMs)is investigated in this paper.Since the armature windings and PMs are located in two separated stators and PMs are stationary,PS-SFPMMs have high fault tolerance capabilities.To maximize the torque performance,the PM of inner stator pole should be aligned with outer stator pole when n is odd while the iron rib of inner stator pole should be aligned with outer stator pole when n is even.No matter what n is selected,the rotor pole number NR can be any integers except the phase number and its multiples.The analysis results indicate that the optimal NR is closed to(NIS+NOS)/2 and it is odd when n is odd while it is even when n is even.Meanwhile,symmetrical phase back-EMF waveform will be obtained when the ratio of Min(NOS,NIS)to the greatest common divisor of Min(NOS,NIS)and NR is even.Based on the optimal rotor pole numbers for 6-pole outer stator with different n and corresponding optimal relative position together with same rated copper loss,the average torque is improved by 18.4%,25.1%and 25.7%respectively in PS-SFPMMs with n equal to 2,3 and 4 when compared with PS-SFPMM with n equal to 1.The analyses are validated by experiment results of the prototype machine.

Research on resonance parameters matching based on partitioned operation method of atmospheric pressure plasma reactor array

Matching optimization of resonant parameters among the high power inverters,low power transformers and plasma reactors have significant effects on the performance and output of the reactor array when applying the partitioned operation method.In this paper,the Matlab/Simulink electrical model was established based on the method of partitioned operation.The matching relation between resonant parameters is analyzed on the basis of experimental result.As a consequence,transformer leakage inductance and working frequency are the important parameters influencing the operational efficiency of system,leakage inductance of transformer should be adjusted based on the equivalent capacitance of plasma reactor to realize the matching optimization of resonant parameters.

Fluid-Structure Interaction Analysis of Flexible Plate with Partitioned Coupling Method

The development and rapid usage of numerical codes for fluid-structure interaction(FSI) problems are of great relevance to researchers in many engineering fields such as civil engineering and ocean engineering. This multidisciplinary field known as FSI has been expanded to engineering fields such as offshore structures, tall slender structures and other flexible structures applications. The motivation of this paper is to investigate the numerical model of two-way coupling FSI partitioned flexible plate structure under fluid flow. The adopted partitioned method and approach utilized the advantage of the existing numerical algorithms in solving the two-way coupling fluid and structural interactions. The flexible plate was subjected to a fluid flow which causes large deformation on the fluid domain from the oscillation of the flexible plate. Both fluid and flexible plate are subjected to the interaction of load transfer within two physics by using the strong and weak coupling methods of MFS and Load Transfer Physics Environment, respectively. The oscillation and deformation results have been validated which demonstrate the reliability of both strong and weak method in resolving the two-way coupling problem in contribution of knowledge to the feasibility field study of ocean engineering and civil engineering.

Array Shape Estimation Using Partitioned Eigenstructure Method with Sources in Unknown Localizations

Advanced array processing approaches require accurate knowledge of the location of individual element in a sensor array.Most array shape estimation methods require the directions of sources.In this paper,an array shape estimation method based on eigen-decomposition is presented.The directions of sources do not need to be considered in advance and optimal array shape is generated through a series of iterations.To further improve the accuracy of this algorithm,a partitioned eigenstructure method is introduced.Numerical simulations using non-partitioned and partitioned method are conducted to verify the performance of the proposed technique.

Transient Free Convection and Heat Transfer in a Partitioned Attic-Shaped Space under Diurnal Thermal Forcing

One primordial consideration in residential ventilation standards is the comfort of provided to people living in those habitations.This is highly dependent on the thermal and fluid flow conditions,the space geometry and so on.Efficient designs may reduce the energy usage,making the buildings more sustainable over a longer period of time.This study aims to investigate the impact of whole day thermal conditions on the fluid flow structure and heat transfer phenomena,mainly natural convection,inside a partitioned attic-shaped configuration.The Finite Volume Method is applied to solve the governing equations.Sinusoidal thermal boundary condition is applied on the sloping walls to illustrate the characteristics of primary flow through daily cycles.A highly thermal conductive partition was placed vertically at the middle of the cavity.Note that through the partition,only heat could freely transfer between two fluid zones.Results show that,during day time,a stratified fluid flow structure is obtained,which originates from the prevailing conduction heat transfer mechanism,while,for the night-time it changed into a strong convection mechanism which significantly affects the flow structure.These results are particularly important for understanding the fluid dynamics inside the attic shaped building and also designing new residential building.

Strong Stability Preserving IMEX Methods for Partitioned Systems of Differential Equations

We investigate strong stability preserving(SSP)implicit-explicit(IMEX)methods for partitioned systems of differential equations with stiff and nonstiff subsystems.Conditions for order p and stage order q=p are derived,and characterization of SSP IMEX methods is provided following the recent work by Spijker.Stability properties of these methods with respect to the decoupled linear system with a complex parameter,and a coupled linear system with real parameters are also investigated.Examples of methods up to the order p=4 and stage order q—p are provided.Numerical examples on six partitioned test systems confirm that the derived methods achieve the expected order of convergence for large range of stepsizes of integration,and they are also suitable for preserving the accuracy in the stiff limit or preserving the positivity of the numerical solution for large stepsizes.

Global Convergence of the Partitioned Broyden's Algorithm for Convex Partially Sepearable Optimizations

In this paper, the so—called partitioned Broyden’s algorithms used for solving Partially seperable optimization with a convex decomposition is concerned. Global convergence is proved for this type of "partitioned updating" quasi-Newton method. The algorithm is well adapted to unconstrained problems involving many variables.

A rate-distortion optimized rate shaping scheme for H.264 data partitioned video bitstream

To enable quality sealability and further improve the reconstructed video quallty m rate shaping, a rate-distortion optimized packet dropping scheme for H. 264 data partitioned video bitstream is proposed in this paper. Some side information is generated for each video bitstream in advance, while streaming such side information is exploited by a greedy algorithm to optimally drop partitions in a rate-distortion optimized way. Quality sealability is supported by adopting data partition instead of whole frame as the dropping unit. Simulation resuhs show that the proposed scheme achieves a great gain in the reconstructed video quality over two typical frame dropping schemes, with the help of the fine granularity in dropping unit as well as rate-distortion optimization.

System Vulnerability Analysis Using Graph Pathfinding Strategies in Partitioned Networks

In this paper, a new method has been introduced to find the most vulnerable lines in the system dynamically in an interconnected power system to help with the security and load flow analysis in these networks. Using the localization of power networks, the power grid can be divided into several divisions of sub-networks in which, the connection of the elements is stronger than the elements outside of that division. By using our proposed method, the probable important lines in the network can be identified to do the placement of the protection apparatus and planning for the extra extensions in the system. In this paper, we have studied the pathfinding strategies in most vulnerable line detection in a partitioned network. The method has been tested on IEEE39-bus system which is partitioned using hierarchical spectral clustering to show the feasibility of the proposed method.

Highly Available Hypercube Tokenized Sequential Matrix Partitioned Data Sharing in Large P2P Networks

Peer-to-peer (P2P) networking is a distributed architecture that partitions tasks or data between peer nodes. In this paper, an efficient Hypercube Sequential Matrix Partition (HS-MP) for efficient data sharing in P2P Networks using tokenizer method is proposed to resolve the problems of the larger P2P networks. The availability of data is first measured by the tokenizer using Dynamic Hypercube Organization. By applying Dynamic Hypercube Organization, that efficiently coordinates and assists the peers in P2P network ensuring data availability at many locations. Each data in peer is then assigned with valid ID by the tokenizer using Sequential Self-Organizing (SSO) ID generation model. This ensures data sharing with other nodes in large P2P network at minimum time interval which is obtained through proximity of data availability. To validate the framework HS-MP, the performance is evaluated using traffic traces collected from data sharing applications. Simulations conducting using Network simulator-2 show that the proposed framework outperforms the conventional streaming models. The performance of the proposed system is analyzed using energy consumption, average latency and average data availability rate with respect to the number of peer nodes, data size, amount of data shared and execution time. The proposed method reduces the energy consumption 43.35% to transpose traffic, 35.29% to bitrev traffic and 25% to bitcomp traffic patterns.

Temperature fluctuations and heat transport in partitioned supergravitational thermal turbulence

We report an experimental study of the local temperature fluctuationsδT and heat transport in a partitioned supergravitational turbulent convection system.Due to the dynamics of zonal flow in the normal system without partition walls,the probability density function(PDF)at a position in the mixing zone exhibits a downward bending shape,suggesting that the multi-plume clustering effect plays an important role.In partitioned system,zonal flow is suppressed and the PDFs indicate that the single-plume effect is dominant.Moreover,statistical analysis shows that the PDF ofδT is sensitive to supergravity.Additionally,the thermal spectra follow P(f)∼f^(-5) in the normal system,which is relevant to the zonal flow.The absolute value of the scaling exponent of P(f)and the scaling range become small in the partitioned system,which provides another evidence for the influence of zonal flow on the energy cascade.Further,heat transfer enhancement is found in the partitioned system,which may result from zonal flow being restricted and then facilitating the radial movement of thermal plumes to the opposite conducting cylinder.This work may provide insights into the flow and heat transport control of some engineering and geophysical flows.

Novel Partitioned Time-Stepping Algorithms for Fast Computation of Random Interface-Coupled Problems with Uncertain Parameters

The simulation of multi-domain,multi-physics mathematical models with uncertain parameters can be quite demanding in terms of algorithm design and com-putation costs.Our main objective in this paper is to examine a physical interface coupling between two random dissipative systems with uncertain parameters.Due to the complexity and uncertainty inherent in such interface-coupled problems,un-certain diffusion coefficients or friction parameters often arise,leading to consid-ering random systems.We employ Monte Carlo methods to produce independent and identically distributed deterministic heat-heat model samples to address ran-dom systems,and adroitly integrate the ensemble idea to facilitate the fast calcu-lation of these samples.To achieve unconditional stability,we introduce the scalar auxiliary variable(SAV)method to overcome the time constraints of the ensemble implicit-explicit algorithm.Furthermore,for a more accurate and stable scheme,the ensemble data-passing algorithm is raised,which is unconditionally stable and convergent without any auxiliary variables.These algorithms employ the same co-efficient matrix for multiple linear systems and enable easy parallelization,which can significantly reduce the computational cost.Finally,numerical experiments are conducted to support the theoretical results and showcase the unique features of the proposed algorithms.

Competitive role of film-like austenite and transition carbides on hydrogen embrittlement resistance and impact toughness in bainite-containing quenched and partitioned steel

A microstructure composed of martensite matrix,lower bainite,and stable film-like austenite was designed by a quenching and isothermal bainitic holding process in a 0.30C–2.69Mn–1.71Si(wt.%)steel.The yield strength,tensile strength,and ductile-to-brittle transition temperature(DBTT)of the high-strength steel thus obtained were 1263 MPa,1521 MPa,and-33℃,respectively,and at-20℃,it showed superior low-temperature toughness,which reached 77.5 J/cm^(2).Meanwhile,it showed excellent hydrogen embrittlement(HE)resistance,and the total elongation loss is only 3.1%after 15 min of hydrogen charging.The excellent comprehensive performance is attributed to the fact that fine stable austenite with film-like morphology hindered the crack nucleation and propagation,and hindered hydrogen diffusion as a hydrogen trap.However,with a decrease in the isothermal temperature,transition carbide precipitation was accompanied by a further decrease in austenite grain size.For this condition,although transition carbides can act as effective hydrogen traps,excessive precipitation decreased the carbon content of retained austenite and increased the deformation heterogeneity between austenite and martensite matrix,leading to weakened austenite stability and HE resistance,a total elongation loss of approximately 39%(15 min hydrogen charging),a sharp decrease in impact toughness,and an increase in DBTT.The competitive role of film-like austenite and transition carbides on the comprehensive mechanical performance of steel is revealed,especially the suppression of crack nucleation and propagation that will provide a guide for the design of high strength steels with excellent impact toughness and HE resistance.