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In this paper, a novel locking-free finite beam element is proposed utilizing the absolute nodal coordinate formulation. By incorporating a gradient vector along the transverse direction at the boundary points, the linear interpolation of the gradient vector field within this element is achieved. Consequently, the problem of constant transverse strain distribution, which is observed in the Omar–Shabana beam element, is effectively addressed. Building upon this concept, this study further extends the proposed element from two dimensions to three dimensions. Additionally, it analyzes and compares the locking alleviation mechanism of the newly developed element and Patel–Shabana beam element. The analysis aims to provide insights into the factors contributing to the locking alleviation of different absolute nodal coordinate formulation (ANCF) elements. Furthermore, to demonstrate the effectiveness of the new element, six numerical simulation examples are designed, comprising three and three dynamic examples. These examples encompass small deformation statics, large deformation statics, small-scale motion, large-scale motion, and rotational motion problems. Finally, the results indicate that the proposed ANCF beam element can effectively alleviate the locking problem. The element exhibits robust adaptability, rationality, and effectiveness when subjected to complex mechanical characteristics by comparing the numerical results of this element with the classical Omar–Shabana, high-order Shen, and Patel–Shabana elements. [ABSTRACT FROM AUTHOR]

In this paper, we propose a computational method for rapidly estimating the gravitational acceleration of irregular asteroids: the pseudocenter theory, triangular mesh, kriging interpolation (PTK) method. The method first uses a triangular mesh to discretize the asteroid's surface. Then, the fitting coefficients of all grid point directions are obtained using pseudocenter theory. Finally, kriging interpolation is used to quickly estimate the gravitational acceleration value at any location. Numerical simulation shows that the PTK method can ensure a high calculation speed, wide application range, and high accuracy with an extremely low storage cost. Overall, the PTK method is more balanced, faster, and more feasible than current methods for calculating gravitational acceleration for on-orbit use. [ABSTRACT FROM AUTHOR]

In this paper, we propose an extended aperture direction-of-arrival (DOA) estimation algorithm using a coprime acoustic vector sensor array. Each acoustic vector sensor consists of one pressure sensor and one uniaxial velocity sensor, collocated in a single point in space. By full utilization of both pressure and particle-velocity information in the acoustic wavefield, the whole coarray output is shown to be treated as four pressure–velocity (p–v) components. In this way, array interpolation and Toeplitz matrix reconstruction are performed on each of the four p–v components to exploit the entire coarray aperture. After interpolation, DOA estimates are derived in closed form using the interpolated coarray data. The proposed algorithm allows the inter-sensor spacing of the interpolated coarray to be significantly greater than half a wavelength, thereby achieving aperture extension without needing extra sensors. Moreover, it enables provide the unambiguous DOA estimates with high accuracy, despite the phase aliasing caused by aperture extension. All these advantages are not offered by the existing coprime array DOA estimation algorithms. Finally, computer simulations are carried out to verify the superiority of the proposed algorithm. [ABSTRACT FROM AUTHOR]

We present and analyse the performance of different combinations of four higher-order numerical integrators and up to nine interpolation schemes applied to the problem involving the Sun and four Gas-giants (outer planets), namely, Jupiter, Saturn, Uranus, and Neptune. The Hermite interpolation schemes obtained by one, two, and three time-step and interpolants for ODEX2 and ERKN integrators are considered in this paper. The interpolants are a special example of an interpolation scheme, which produce an approximation that is continuous across one step and across the complete interval of integration. The interpolants are quite expensive in comparison with the other interpolation schemes. Therefore, one of the objectives of this paper is to investigate the possibilities of replacing the interpolants of certain integrators by other interpolation schemes, perhaps at a cost of a little bit of accuracy. The experiments are performed to examine the error growth in the positions, velocities, and relative error in energy and angular momentum using different combinations of integrators and interpolation schemes over a long interval of integration, as long as 100 million years for the Jovian problem with local error tolerances ranging from 10-16 to 10-08. [ABSTRACT FROM AUTHOR]

Abstract In this paper, for the first time, fractional Taylor–Jumarie series expansion is used to solve a glass of time-fractional delay partial differential equation by piecewise interpolation reproducing kernel method (RKM), this class of equations describe sand motion model in beach formation. The aim of this work is to obtain more accurate numerical solution by fractional Taylor–Jumarie series expansion and piecewise interpolation technique. Three numerical experiments are provided to show the advantage of this method, the results show the characteristics of sand motion. The research in this paper is the theoretical basis for further sand motion study. [ABSTRACT FROM AUTHOR]

In this paper, two new decoding algorithms to decode Reed–Solomon codes during transmission over burst Rayleigh fading channels with additive white Gaussian noise (AWGN) are proposed. They only conduct error correction for coded symbols located in the pure AWGN region and conduct error and erasure correction for those symbols located in the burst fading region by treating those coded symbols that are very likely erroneous as erasures. The first algorithm does not need to know the fading locations in advance, while the second algorithm assumes that the fading locations are known. In addition, the performance of such two algorithms is studied when a pre-computed threshold is used to determine the erasures of the code. Simulation results show that our proposed algorithms not only significantly perform better than the classic Berlekamp–Messay algorithm with a comparable computational complexity but also achieve a better tradeoff between the performance and the computational complexity when compared with other existing algorithms. In particular, our algorithms exhibit excellent robustness for tested various code parameters and fading configurations. Furthermore, a more detailed mathematical analysis is also developed in this paper in order to estimate the performance of the new algorithms in the burst Rayleigh fading channels. We observe that the performance of the first algorithm can only be estimated relatively accurately when encountering burst deep-fading, whereas the performance prediction for the second algorithm is always in agreement with the simulation results for various fading cases. [ABSTRACT FROM AUTHOR]

Focused on the problems that low-precision and easily to fall into local optimum result in the high-dimensional space by the longhorn search algorithm,this paper proposed a new optimization algorithm of the short-lived beetles-the shortlived search algorithm based on quadratic interpolation which was called QIBAS.The algorithm took tentacle’s left and right tentacles as interpolation coordinate points after the beetle moved.And it generated new solution with a second interpolation,then compared to the current optimal solution and the global optimal solution with the fitness of interpolation solution.At the same time to update the global optimal solution,it performed numerical simulation tests on multiple unimodal and multimodal functions,and their dimensions took as 100,500,1 000,5 000 and 10 000.The simulation results show that the introduction of quadratic interpolation effectively improves the ability of the BAS algorithm to jump out of the local optimum.When QIBAS solves the optimal value,its solution accuracy is greatly improved,and the convergence speed is also significantly improved.The effectiveness of the improved algorithm is verified. [ABSTRACT FROM AUTHOR]

Identifying the surrounding rock loads acting on the external shield surface is critical to the safe construction of deep and long tunnels excavated by TBMs (tunnel boring machines). However, it is rather difficult or even impossible to carry out monitoring outside the TBM shield to directly determine the surrounding rock loads. In the present paper, based on modified Newton iteration and numerical simulation, an inverse analysis approach to identify the surrounding rock loads is proposed. This inverse problem is solved by minimizing the objective function that incorporates the difference between the monitored and calculated strains of discrete points on the internal TBM shield surface. During the inverse analysis, the external TBM shield surface is discretized into rectangular regions, and the nodal loads of each region are taken as the inverse parameters. Then, the distributed loads are approximately calculated by the interpolation of the nodal loads of each region. The proposed approach is calibrated with two numerical examples and then applied to analyze in situ monitoring data. The results show that the proposed approach is robust and efficient for identifying the distribution and magnitude of surrounding rock loads, and it is possible to carry out timely countermeasures to avoid shield jamming according to the identified loads. [ABSTRACT FROM AUTHOR]

Polynomial interpolation is widely used in channel modeling for aerospace tracking, telemetry, and command channel simulators, to accurately regenerate the satellite motion parameters with a high sampling rate from the available low sampling rate motion data. In this paper, a novel piecewise osculating interpolation approach is proposed to improve modeling precision. It uses the available distance and its higher-order derivatives at each pair of adjacent knots to construct the piecewise interpolation polynomial, thus achieving a better precision and continuity of the resulting motion parameters. Moreover, it is efficiently implemented with an interpolation filter based on a modified Farrow structure, and the designed filter can interpolate the motion data obtained both through uniform or nonuniform sampling. Additionally, a sampling optimization algorithm is proposed. It optimizes the motion data sampling by minimizing the maximum interpolation error given the average sampling interval and interpolation polynomial order, and therefore, improves the precision further without increasing the costs. The validity of the proposed approach is verified by numerical simulation, and its advantages are demonstrated by comparison with existing methods. [ABSTRACT FROM AUTHOR]

This paper is devoted to the investigation of the electromagnetic scattering problems from infinite perfectly conducting cylinders with arbitrary cross-sections. The problems can be mathematically modeled as surface integral equations. Both the electric field integral equation (EFIE), magnetic field integral equation (MFIE) and their combined form are studied. An efficient computational technique based on the local radial point interpolation method is performed to investigate the models. Some test problems with various cross-sections have been analyzed to validate the capability of the proposed technique in calculating the current distribution induced on the scatterer and measuring the Radar Cross Section. [ABSTRACT FROM AUTHOR]

In this paper, dynamical behavior of a mathematical model for the interaction of nutrient phytoplankton and its predator zooplankton is investigated numerically. Stability analysis of the phytoplankton–zooplankton model is studied by using the fractional Routh–Hurwitz stability conditions. We have studied the local stability of the equilibrium points. Then a new numerical algorithm, as well as its modification for solving fractional differential equations (FDEs) based on the polynomial interpolation, is proposed. The algorithms are designed to estimate linear and nonlinear FDEs and they have the capability to apply for solving fractional order systems. The convergence order and stability of the fractional higher order algorithms are proved and stability regions of the algorithms are achieved. Extensive numerical simulation results are provided and compared with the literature for illustrating the effectiveness and applicability of the presented algorithms to solve fractional differential equations. The obtained analytical results are validated by numerical simulations and the global dynamics of the model system is studied. [ABSTRACT FROM AUTHOR]

Nadir viewing satellite image is an effective data source to generate orthomosaics. Because of the georeferencing error of satellite images, block adjustment is the first step of orthomosaic generation over a large area. However, the geometric relationship of the neighboring orbits of the nadir viewing images is not rigid enough. This paper proposes a new rational function model (RFM) block adjustment approach that constrains the tie point elevation to enhance the relative geometric rigidity. By interpolating the elevations of tie points in a digital elevation model (DEM) and estimating the a priori errors of the interpolated elevations, better overall relative accuracy is obtained, and the local optimal solution problem is avoided. By constraining the adjusted model parameters according to the a priori error of RFMs, block adjustment without ground control point (GCP) is performed. By optimal initializing the object–space positions of tie points with multi-backprojection method, the needed iteration times of block adjustment are reduced. The proposed approach is investigated with 46 Ziyuan-3 sensor-corrected images, a 1:50 000 scale DEM, and 586 GCPs. Compared with Teo's approach that constrains the horizontal coordinates and elevations of tie points, the approach in this paper converges much faster when the GCPs are sparse, and meanwhile, the absolute and relative accuracy of the two approaches are almost the same. The result of block adjustment with only four GCPs shows that no accuracy degeneration occurred in the test area and the root-mean-square error of independent check point reaches about 1.5 ground resolutions. Different DEMs and number of tie points are used to investigate whether the block adjustment result is influenced by these factors. The results show that better DEM accuracy and denser tie points do improve the accuracy when the images have large side-sway angles. The proposed approach is also tested with 5118 IKONOS-2 images that cover the southern Europe without GCP. The result shows that the relative mosaicking accuracy is much better than that of Grodecki's approach. [ABSTRACT FROM PUBLISHER]

In spline toolpath interpolation, a crucial point is solving the mapping between the spline parameter (u) and actual arc length (s) accurately, so that the toolpath is traveled without undesirable fluctuations or discontinuities in the feedrate profile. To achieve this, various techniques have been proposed in literature, including Taylor series interpolation, iterative numerical methods, and approximating the mapping between u and s with a feed correction polynomial. This paper presents a new way to parameterize the seventh order feed correction polynomial, which was introduced by Erkorkmaz and Altintas (2005, "Quintic Spline Interpolation With Minimal Feed Fluctuation," ASME J. Manuf. Sci. Eng., 127(2), pp. 339-349). The proposed technique has a closedform solution that can be efficiently implemented in real-time, rather than having to construct and solve a linear equation system with 14 unknowns for each spline segment. In this paper, the new solution is derived step by step, and simulation case studies are presented which demonstrate that the new method accurately parameterizes the feed correction polynomial in approximately 43% less computational time, compared to applying the former solution of Erkorkmaz and Altintas (2005, "Quintic Spline Interpolation With Minimal Feed Fluctuation," ASME J. Manuf. Sci. Eng., 127(2), pp. 339-349). This is because matrix multiplication operations and a dedicated linear equation solver, which are cumbersome to implement inside a real-time computer numerical controller (CNC), are avoided in the new solution. [ABSTRACT FROM AUTHOR]

In the reliability-based design optimization (RBDO) process, surrogate models are frequently used to reduce the number of simulations because analysis of a simulation model takes a great deal of computational time. On the other hand, to obtain accurate surrogate models, we have to limit the dimension of the RBDO problem and thus mitigate the curse of dimensionality. Therefore, it is desirable to develop an efficient and effective variable screening method for reduction of the dimension of the RBDO problem. In this paper, requirements of the variable screening method for deterministic design optimization (DDO) and RBDO are compared, and it is found that output variance is critical for identifying important variables in the RBDO process. An efficient approximation method based on the univariate dimension reduction method (DRM) is proposed to calculate output variance efficiently. For variable screening, the variables that induce larger output variances are selected as important variables. To determine important variables, hypothesis testing is used in this paper so that possible errors are contained in a user-specified error level. Also, an appropriate number of samples is proposed for calculating the output variance. Moreover, a quadratic interpolation method is studied in detail to calculate output variance efficiently. Using numerical examples, performance of the proposed method is verified. It is shown that the proposed method finds important variables efficiently and effectively [ABSTRACT FROM AUTHOR]

In this paper, we deal with numerical analysis of a transport fragmentation coagulation equation with power fragmentation rates and separable coagulation kernels. For numerical simulations, the model is rewritten in a conservative form and semi-discretized in space using a Laguerre pseudo-spectral method. Some error estimates are derived and efficiency of the numerical scheme is considered. The paper is concluded with several computational examples. [ABSTRACT FROM AUTHOR]

A new method for the estimation of initial conditions (ICs) in a PM2.5 transport adjoint model is proposed in this paper. In this method, we construct the field of ICs by interpolating values at independent points using the surface spline interpolation. Compared to the traditionally used linear interpolation, the surface spline interpolation has an advantage for reconstructing continuous smooth surfaces. The method is verified in twin experiments, and the results indicate that this method can produce better inverted ICs and less simulation errors. In practical experiments, simulation results show good agreement with the ground-level observations during the 22nd Asia-Pacific Economic Cooperation summit period, demonstrating that the new method is effective in practical application fields. [ABSTRACT FROM AUTHOR]

In this paper a new approach for merging overlapping grids for CFD simulations is presented. The proposed strategy is a preprocessor that integrates the overset meshes into a single mesh suitable for unstructured finite volume vertex-centered Navier–Stokes solvers. This strategy aims to deal with complex industrial problems, specially in case of moving components and overlapping boundary layers. The algorithm consists of two key steps: the definition of a hole cutting area over each component mesh, where nodes of the other mesh are removed, and the subsequent remeshing of the gap generated between both meshes. In this process, the first issue is particularly critical and it employs auxiliary coarse Cartesian meshes to simplify the involved computations like wall distance calculations or point inclusion test. The proposed approach has been demonstrated on 2D test configurations using the DLR-TAU solver [ABSTRACT FROM AUTHOR]

This paper presents a computer efficient approach to evaluate the multi-dimensional integral found in the evaluation of the long-term extreme response of marine structures. The proposed method is a hybrid combination of two numerical procedures. The first one consists of a parabolic interpolation scheme used to obtain the statistical parameters describing the short-term peaks probability distribution of the time-series responses, designated as PIM (Parabolic Interpolation Method), which reduces the total number of short-term structural analyses. The second one is an Artificial Neural Network-based surrogate model which is used to obtain long response time histories based on short finite element-based simulations. The approach is named as HPI-ANNM (Hybrid Parabolic Interpolation – Artificial Neural Network Method). The efficiency and accuracy of the proposed hybrid method is compared with the complete long-term integration method in the analysis of 100-yr characteristic values of cross-section utilization ratios of a Steel Catenary Riser (SCR) connected to a semi-submersible platform in deep water. [ABSTRACT FROM AUTHOR]

An end-to-end network traffic matrix is significantly helpful for network management and for Software Defined Networks (SDN). However, the end-to-end network traffic matrix's inferences and estimations are a challenging problem. Moreover, attaining the traffic matrix in high-speed networks for SDN is a prohibitive challenge. This paper investigates how to estimate and recover the end-to-end network traffic matrix in fine time granularity from the sampled traffic traces, which is a hard inverse problem. Different from previous methods, the fractal interpolation is used to reconstruct the finer-granularity network traffic. Then, the cubic spline interpolation method is used to obtain the smooth reconstruction values. To attain an accurate the end-to-end network traffic in fine time granularity, we perform a weighted-geometric-average process for two interpolation results that are obtained. The simulation results show that our approaches are feasible and effective. [ABSTRACT FROM AUTHOR]

This paper presents a novel real-time (online) interpolation algorithm based on Finite Impulse Response (FIR) filters to generate smooth and accurate reference motion trajectories for machine tools and motion systems. Typically, reference tool-paths are composed of series of linear (G01) or circular (G02) segments. Basic point-to-point (P2P) feed motion can be generated by interpolating each segment with trapezoidal or S-curved velocity profile. However, smooth and accurate transitions between path segments are necessary to realize non-stop contouring motion. In this study, FIR filters are utilized, and the reference tool-path is filtered to interpolate a non-stop rapid feed motion. By using a chain of FIR filters, acceleration and jerk continuous motion profiles are generated from velocity pulse commands. A segment interpolation timing technique is developed to control the contour errors during non-stop real-time interpolation of tool-paths. Furthermore, by utilizing FIR filters for interpolation, frequency spectrum of the interpolated motion profiles is controlled. The time constant (delay) of the filter is tuned to create notches around the lightly damped vibration modes of the motion system, which allows mitigation of unwanted vibrations and thus enables delivering accurate feed motion. Simulation studies and industrial scale experimental validations are provided to illustrate effectiveness of the developed interpolation technique. [ABSTRACT FROM AUTHOR]

The neocognitron is a deep (multi-layered) convolutional neural network that can be trained to recognize visual patterns robustly. In the intermediate layers of the neocognitron, local features are extracted from input patterns. In the deepest layer, based on the features extracted in the intermediate layers, input patterns are classified into classes. A method called IntVec (interpolating-vector) is used for this purpose. This paper proposes a new learning rule called margined Winner-Take-All ( mWTA ) for training the deepest layer. Every time when a training pattern is presented during the learning, if the result of recognition by WTA (Winner-Take-All) is an error, a new cell is generated in the deepest layer. Here we put a certain amount of margin to the WTA. In other words, only during the learning, a certain amount of handicap is given to cells of classes other than that of the training vector, and the winner is chosen under this handicap. By introducing the margin to the WTA, we can generate a compact set of cells, with which a high recognition rate can be obtained with a small computational cost. The ability of this mWTA is demonstrated by computer simulation. [ABSTRACT FROM AUTHOR]

A novel wavefront reconstruction algorithm for radial shearing interferometer (RSI) is proposed in this paper. Based on the shearing relationship of RSI, an interpolation coefficient matrix is established by the radial shearing ratio and the number of discrete points of test wavefront. Accordingly, the expanded wavefront is characterized by the interpolation coefficient matrix and the test wavefront. Consequently the test wavefront can be calculated from the phase difference wavefront. The numerical simulation is conducted to confirm the correctness of the proposed algorithm. Compared with the previous wavefront reconstruction methods, the proposed algorithm is more accurate and stable. [ABSTRACT FROM AUTHOR]

Purpose – This paper aims to present a fast, economical and practical attitude control design approach for flight vehicles operating within wide envelopes. Design/methodology/approach – Based on a linear disturbance observer, an enhanced proportional-derivative (PD) control scheme is proposed. Utilizing the data from the onboard gyro, the observer can treat the entire response of the system, with the exception of the control term, as a disturbance, and use the estimation of the disturbance to cancel out this response and thereby to effectively simplify the control channel. Using the stability margin tester, the explicit graphical tuning rules are given in a consistent way for the longitudinal dynamics based on the induction method. Mathematical simulations are performed for a highly maneuverable flight vehicle to test the proposed method, which are compared with the traditional PD and H8 control algorithms. Findings – The proposed strategy for attitude control can be reformulated as a static-dynamic control algorithm and the robust synthesis method can be employed to determine the control parameters according to a specific performance configuration. The remarkable control performance robustness can be achieved as shown in the comparative simulations. Practical implications – There is a sole parameter, steady gain, needed to be scheduled and it can be estimated with a high accuracy. Originality/value – This paper applies the linear active disturbance rejection control scheme to flight control scenario. The proposed method can reduce the design and implementation complexity of attitude control for flight vehicles operating within a wide envelope, which originates from diverse time-varying flight dynamics. The new method converts the attitude control problem to a sole parameter gain scheduling problem, and there is no complicated and time-consuming multi-dimension interpolation needed for the control parameters. [ABSTRACT FROM AUTHOR]

The advanced manufacture technology requires that multi-axis coordinated motion computer numerical control (CNC) machine tools have the capability of high smoothness and high precision. At present, the study of the motion smoothness mainly concentrates on the acceleration and deceleration control method and the look-ahead process of velocity planning in the interpolation stage. The control strategy of the contouring error mainly focuses on tracking error control, cross-coupling control, and optimal control. In order to improve the motion smoothness and contouring precision for multi-axis high-speed CNC machine tools, a multi-axis modified generalized predictive control approach was presented in this paper. In the control strategy, the estimation models of tracking error, contouring error, velocity error, and acceleration error were structured separately. A new improved quadratic performance index was proposed to guarantee the minimum of these errors. Generalize predictive control was also introduced, a multi-axis generalized predictive control model was deduced for motion smoothness and machining precision for multi-axis coordinated motion CNC system, and an approved multi-axis generalized predictive controller based on the model was designed in this paper. The proposed predicted control approach was evaluated by simulation and experiment of circular, noncircular, and space line trajectories, respectively. These simulative and experimental results demonstrated that the proposed control strategy can significantly improve the motion smoothness and contouring precision. Therefore, the new position control method can be used for the servo control system of multi-axis coordinated motion CNC system, which increases motion smoothness and machining precision of CNC machine tools. [ABSTRACT FROM AUTHOR]

Most motion correction methods work by aligning a set of volumes together, or to a volume that represents a reference location. These are based on an implicit assumption that the subject remains motionless during the several seconds it takes to acquire all slices in a volume, and that any movement occurs in the brief moment between acquiring the last slice of one volume and the first slice of the next. This is clearly an approximation that can be more or less good depending on how long it takes to acquire one volume and in how rapidly the subject moves. In this paper we present a method that increases the temporal resolution of the motion correction by modelling movement as a piecewise continous function over time. This intra-volume movement correction is implemented within a previously presented framework that simultaneously estimates distortions, movement and movement-induced signal dropout. We validate the method on highly realistic simulated data containing all of these effects. It is demonstrated that we can estimate the true movement with high accuracy, and that scalar parameters derived from the data, such as fractional anisotropy, are estimated with greater fidelity when data has been corrected for intra-volume movement. Importantly, we also show that the difference in fidelity between data affected by different amounts of movement is much reduced when taking intra-volume movement into account. Additional validation was performed on data from a healthy volunteer scanned when lying still and when performing deliberate movements. We show an increased correspondence between the “still” and the “movement” data when the latter is corrected for intra-volume movement. Finally we demonstrate a big reduction in the telltale signs of intra-volume movement in data acquired on elderly subjects. [ABSTRACT FROM AUTHOR]

The state of the art for mesh coupling at nonconforming interfaces is presented and reviewed. Mesh coupling is frequently applied to the modeling and simulation of motion in electromagnetic actuators and machines. The paper exploits Whitney elements to present the main ideas. Both interpolationand projection-based methods are considered. In addition to accuracy and efficiency, we emphasize the question whether the schemes preserve the structure of the de Rham complex, which underlies Maxwell's equations. As a new contribution, a structure-preserving projection method is presented, in which Lagrange multiplier spaces are chosen from the Buffa-Christiansen complex. Its performance is compared with a straightforward interpolation based on Whitney and de Rham maps, and with Galerkin projection. [ABSTRACT FROM AUTHOR]

This paper presents a parametric numerical investigation of solidification around two cooled cylinders placed in tandem under forced convection. The front-tracking/finite difference method is used together with an interpolation technique for solving the phase change process. Evolution of the solidifying interface is followed by the front-tracking, and the interpolation handles the presence of the solid phase and the no-slip and constant isothermal boundary conditions. The effects of various non-dimensional parameters on the evolution of the solid phase such as the Reynolds number Re , the Stefan number St , the dimensionless temperature of the inflowing liquid θ 0 , the ratios of the thermal properties k sl and C psl , and the distance between two cylinders L are studied. The computational results show that the solidified region expands with an increase in k sl or L , or with a decrease in any one of Re, Pr, θ 0 . However, St and C psl have a minor effect on the final form of the solid phase. The effect of density difference between the solid and liquid phases, and results in the case of side-by-side arrangement are also presented. [ABSTRACT FROM AUTHOR]

This paper presents a finite element that incorporates weak, strong and both weak plus strong discontinuities with linear interpolations of the unknown jumps for the modeling of internal interfaces. The new enriched space is built by subdividing each triangular or tetrahedral element in several standard linear sub-elements. The new degrees of freedom coming from the assembly of the sub-elements can be eliminated by static condensation at the element level, resulting in two main advantages: first, an elemental enrichment instead of a nodal one, which presents an important reduction of the computing time when the internal interface is moving all around the domain and second, an efficient implementation involving minor modifications allowing to reuse existing finite element codes. The equations for the internal interface are constructed by imposing the local equilibrium between the stresses in the bulk of the element and the tractions driving the cohesive law, with the proper equilibrium operators to account for the linear kinematics of the discontinuity. To improve the continuity of the unknowns on both sides of the elements on which a static condensation is done, a contour integral has been added. These contour integrals named inter-elemental forces can be interpreted as a “do nothing” boundary condition (Coppola-Owen and Codina, 2011) published in another context, or as the usage of weighting functions that ensure convergence of the approach as proposed by J.C. Simo (Simo and Rifai, 1990). A series of numerical tests for scalar unknowns as a simple representation of more general numerical simulations are presented to illustrate the performance of the enriched elemental space. [ABSTRACT FROM AUTHOR]

Monitoring the status of urban environments, which provides fundamental information for a city, yields crucial insights into various fields of urban research. Recently, with the popularity of smartphones and vehicles equipped with onboard sensors, a people-centric scheme, namely "crowdsensing", for city-scale environment monitoring is emerging. This paper proposes a data correlation based crowdsensing approach for fine-grained urban environment monitoring. To demonstrate urban status, we generate sensing images via crowdsensing network, and then enhance the quality of sensing images via data correlation. Specifically, to achieve a higher quality of sensing images, we not only utilize temporal correlation of mobile sensing nodes but also fuse the sensory data with correlated environment data by introducing a collective tensor decomposition approach. Finally, we conduct a series of numerical simulations and a real dataset based case study. The results validate that our approach outperforms the traditional spatial interpolation-based method. [ABSTRACT FROM AUTHOR]

Anonymity, which is more and more important to multi-receiver schemes, has been taken into consideration by many researchers recently. To protect the receiver anonymity, in 2010, the first multi-receiver scheme based on the Lagrange interpolating polynomial was proposed. To ensure the sender’s anonymity, the concept of the ring signature was proposed in 2005, but afterwards, this scheme was proven to has some weakness and at the same time, a completely anonymous multi-receiver signcryption scheme is proposed. In this completely anonymous scheme, the sender anonymity is achieved by improving the ring signature, and the receiver anonymity is achieved by also using the Lagrange interpolating polynomial. Unfortunately, the Lagrange interpolation method was proven a failure to protect the anonymity of receivers, because each authorized receiver could judge whether anyone else is authorized or not. Therefore, the completely anonymous multi-receiver signcryption mentioned above can only protect the sender anonymity. In this paper, we propose a new completely anonymous multi-receiver signcryption scheme with a new polynomial technology used to replace the Lagrange interpolating polynomial, which can mix the identity information of receivers to save it as a ciphertext element and prevent the authorized receivers from verifying others. With the receiver anonymity, the proposed scheme also owns the anonymity of the sender at the same time. Meanwhile, the decryption fairness and public verification are also provided. [ABSTRACT FROM AUTHOR]

One of the chief challenges of the finite-difference time-domain (FDTD) subgridding algorithm is developing a field-coupling scheme to avoid late-time instability resulting from spatial interface between regions with different meshes. This paper introduces the concept of the nonuniform grid method to appropriately handle the tangential electric component on the spatial interface of the two meshes. This study analyzed shielding effectiveness of metallic enclosures with apertures. A novel subgridding algorithm was employed to locally refine the region containing a thin perfect electric conducting (PEC) film with apertures through FDTD simulation. Image theory was implemented to obtain an interpolation scheme of the magnetic fields as the sub-boundary surface when a thin PEC film traverses the subgridding interface. The numerical accuracy and stability of the proposed method were verified by comparing with results from other established methods. [ABSTRACT FROM PUBLISHER]

Loewner matrix (LM) interpolation-based macromodeling methods can generate an accurate macromodel for large and complex structures. However, there is less flexibility in the choice of the macromodel order due to the need to ensure passivity. In this paper, an algorithm is proposed to obtain a reduced order model based on LM interpolation while still maintaining the passivity of the macromodel. This is achieved by first relaxing the passivity requirement during the order selection process; then a new passivity enforcement scheme with significantly improved speed and convergence properties is applied. The proposed approach results in a significantly reduced macromodel size while maintaining accuracy and passivity conditions. The efficiency of the new approach is shown in the examples. [ABSTRACT FROM PUBLISHER]

Abstract: The objective of this work is to develop finite elements for the simulation of thin Kirchhoff rods, that is, rods where the influence of transverse shear strain can be neglected leading to governing equations that require C 1-continuous finite element interpolations. We start in this paper with the formulation of new finite elements for the infinitesimal plane deformations of otherwise generally curved rods, addressing in particular the lack of invariance observed in related traditional treatments of plane arches. By non-invariance we mean that the classical rigid-body modes of translations and infinitesimal rotations of the underlying structural theory lead to non-zero strains in the element, an effect sometimes referred to as self-straining. This phenomenon occurs in curved configurations of the elements and, in the infinitesimal setting of interest in this paper, it results in the elements stiffness matrix not to exhibit the correct zero-energy modes associated with these physical rigid-body motions. As a consequence, the basic equilibrium relations of balance of forces and moments are not satisfied for the associated nodal forces and moments in non-invariant finite elements. In this context, we propose a new framework for the formulation of C 1-continuous finite elements based on Hermitian shape functions that do lead to the satisfaction of this fundamental invariance property, accounting fully for the rod’s curvature and associated Kirchhoff’s kinematics in contrast to common straight (framework) element approximations based on the simplified Euler–Bernoulli beam kinematics. The formulation relies crucially on a consistent treatment of the kinematics and the assumed interpolation of the rods geometry. An additional assumed strain treatment is considered to avoid limitations of membrane locking. Complete rigorous analyses and several numerical simulations are presented to prove and illustrate the properties and performance of the newly proposed finite element methods. [Copyright &y& Elsevier]

The premixed turbulent V-flame is numerically simulated in this paper. The technique used in Chan et al. [Effect of intense turbulence on turbulent premixed V-flame, Int. J. Eng. Sci. 41 (2003), pp. 903-916; Simulation of a premixed turbulent flame with the discrete vortex method, Int. J. Numer. Methods Eng. 48 (2000), pp. 613-627] was based on the random vortex method and the conventional level set method. However, this paper is an improvement of the previous technique by using a conservative level set method. The new algorithm uses a bi-cubic interpolation process together with Newton's method to reconstruct the velocity field to improve the conservation of the level set method. The numerical example in this paper indicates the efficiency of the new method in solving the problem of turbulent premixed V-flame by comparing the results with available data. [ABSTRACT FROM AUTHOR]

This paper concerns kernel-based interpolation methods for vector data with correlated components. It gives conditions for a matrix kernel to be conditionally positive definite in an appropriate sense. The conditions allow construction of matrix kernels from nonsymmetric mixtures and scalings of scalar kernels. In particular the kernel used to model the influence of component i on component j can be different from that used to model the influence of component j on component i. The vector modeling techniques considered are particularly appropriate when there are relatively few measurements of one quantity and relatively many of another "correlated" quantity. The paper concludes with some numerical tests on model problems. [ABSTRACT FROM AUTHOR]

This paper proposes a hybrid adaptive sampling algorithm to automate the generation of reduced order models for systems described by large-scale frequency dependent state-space models. The evaluation of the frequency dependent state-space model for each frequency sample can be computationally expensive. The distribution of frequency samples must be optimized to avoid oversampling and undersampling. In order to have an optimum number of frequency samples, the proposed algorithm uses the reflective exploration technique for the adaptive selection of samples, and the sampling is further refined using a binary search to validate the frequency dependent reduced order models. Projection-based model order reduction techniques are used for obtaining the reduced order model. The projection matrix for each frequency sample is merged to obtain a common projection matrix for all samples. However, in certain cases when the number of sample points increases, the merged projection matrix also increases in dimension and might fail to provide a satisfactory reduction in model size. Thus, the merged projection matrix is truncated based on its singular values to obtain a compact common projection matrix. Then, the reduced order state-space matrices per frequency are interpolated over the frequency range of interest to obtain the system response. Pertinent examples validate the proposed hybrid adaptive sampling algorithm. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

In the sound field with multiple non-stationary sources, the measured pressure is the sum of the pressures generated by all sources, and thus cannot be used directly for studying the vibration and sound radiation characteristics of every source alone. This paper proposes a separation model based on the interpolated time-domain equivalent source method (ITDESM) to separate the pressure field belonging to every source from the non-stationary multi-source sound field. In the proposed method, ITDESM is first extended to establish the relationship between the mixed time-dependent pressure and all the equivalent sources distributed on every source with known location and geometry information, and all the equivalent source strengths at each time step are solved by an iterative solving process; then, the corresponding equivalent source strengths of one interested source are used to calculate the pressure field generated by that source alone. Numerical simulation of two baffled circular pistons demonstrates that the proposed method can be effective in separating the non-stationary pressure generated by every source alone in both time and space domains. An experiment with two speakers in a semi-anechoic chamber further evidences the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

This paper presents a numerical simulation study on coreflood scale derived from a laboratory study conducted on light oil and water-wet sandstone samples from fields at Tempino and Kenali Asam, Sumatra, Indonesia. A rigorous laboratory study prompted a specified surfactant type among dozens of screened samples, i.e. AN3NS and AN2NS-M for Kenali Asam and Tempino, respectively. The coreflood scale numerical simulation study was performed using a commercial simulator, on the basis of the results from the laboratory study, at a constant temperature of 68°C, 0.3 cc/min injection rate and under 120 psia confining pressure. To get better recovery, the cores were tested using surfactant and polymer in a blended mode, containing 0.03% w/w polymer diluted in each field brine, which accommodated around 8000 ppm salinity. The most significant variable in the multiphase flow is the relative permeability curve, which is affected by interfacial tension (IFT) during waterflooding and surfactant-polymer (SP) flooding. This study shows that relative permeability will be shifted at ultra-low IFT (10-3 to 10-4 mN/m). This shifting phenomenon is governed by the interpolation parameter set, which implicitly represents the capillary number. Further work in matching the numerical results to the coreflood was conducted by changing the interpolation parameters. [ABSTRACT FROM AUTHOR]

Reversible image steganographic scheme has become one of main research contents in information hiding field in recent years. Reversibility allows the original images to be completely reconstructed without any distortion after the embedded information has been extracted. Image interpolation is a key image processing method and has been widely applied in imaging processing relevant areas, such as image reconstruction by simulating image adjacent pixels between two-dimensional images. This paper proposed a reversible and adaptive image steganographic algorithm based on a novel interpolation technology, which can improve the performance of information hiding schemes proposed before. The proposed scheme has the benefits of higher embedding capacity with lower computational complexity and better image quality. The experimental results show that the proposed scheme can gain better performance than other state-of-the-art algorithms. [ABSTRACT FROM AUTHOR]

This paper proposes a grinding method for face gears with CNC machines. Interpolation formulas of CNC linkage are deduced based on a five-coordinate machine tool. An analytical model for predicting envelope residual when grinding face gears based on grinding disc wheel is developed. The generating laws of envelope residual for the envelope manner are investigated. The influence of tool feed magnitude on surface envelope residuals is analyzed in circumferential angle direction. The maximum envelope residual increases nonlinearly with incremental angle. A grinding experiment is performed on a CNC grinding machine. The tooth surface deviation indicates that the CNC grinding method is efficient. The variation trends of different feed magnitudes along circumferential angle direction coincide with the simulation results. Finally, the values of envelope residuals are verified by an envelope simulation with software AutoCAD. The study provides an effective approach for parameter selection of highly precise and efficient grinding of face gear. [ABSTRACT FROM AUTHOR]

In this paper, an effective diffusion coefficient derived from previous semi-empirical formula and dynamic grid technology combined with inverse distance interpolation algorithm are applied to simulate wind-induced snow drifting on low-sloped gable roofs. The effective diffusion coefficient enhances the diffusion ability of particles near the wall surface, and the inverse distance interpolation algorithm has an explicit format, which determines the influence of the sample point on the interpolation point according to the interpolation distance, it has a low computational expense and weakens the influence of extreme points. Two measurement parameters, δ H and δ M , are introduced to illustrate the impact of interpolation parameters (power law p and interpolation radius R) on the single grid adjustment and snow cover. By employing these optimisations, sensitivity analyses for simulation parameters are performed, the effects of the saltation layer height, turbulent Schmidt number, falling velocity, time step size, and wind duration on snow distribution are discussed. Finally, the redistributions of snow cover on gable roofs under various wind directions are reproduced, the snow redistribution characteristics and the relationship between roof slope and snow erosion are investigated. The results can provide a reference for predicting snow loads on gable roofs. • A numerical simulation method with a revised diffusion term is proposed, which can enhance the diffusion ability of particles near the wall surface effectively. • This method and simulation parameters are validated by scaled model experiments. • The impact of simulation parameters is analysed in details. • The redistributions of snow cover on gable roofs under various wind directions are reproduced, the snow redistribution characteristics are investigated. [ABSTRACT FROM AUTHOR]

Free form surfaces are primarily designed and manufactured by CAD/CAM/CNC system. In traditional way, toolpath generation approaches always consider machining precision and efficiency by constraining scallop height and toolpath lengths. However, toolpath lengths do not exactly reflect the actual machining time because the feedrate usually fluctuates along different toolpath during CNC interpolating period, which indicates that the total machining efficiency is coupled with both toolpath generation and interpolation. Therefore, the toolpath generation and interpolation systems should not be independent, and the conventional unidirectional information flow from CAM to CNC should be replaced by a new mechanism with information exchange and mutual optimization. This paper proposes an inverse evaluation mechanism with feedback information from CNC to CAM system. The feedback information is obtained by off-line interpolation simulation for each toolpath and evaluation of the total machining time for the entire surface. With the feedback information, CAM is able to optimize the toolpath or choose the best one among candidate solutions. As the evaluation mechanism should be under the same interpolation algorithm, an interpolation algorithm with axis kinematic/dynamic constraints is also introduced. The simulation results with different free form surfaces show that the proposed mechanism can economically improve the machining efficiency without increasing system cost. [ABSTRACT FROM AUTHOR]

The use of experimental tests that involve full-field measurements to characterize mechanical material properties is becoming more widespread within the engineering community. In particular digital image correlation (DIC) on white light speckles is one of the most used tools, thanks to the relatively low cost of the equipment and the availability of dedicated software. Nonetheless the impact of measurement errors on the identified parameters is still not completely understood. To this purpose, in this paper, a simulator able to numerically simulate an experimental test, which involves DIC is presented. The chosen test is the Unnotched Iosipescu test used to identify the orthotropic elastic parameters of composites. Synthetic images are generated and then analysed by DIC. Eventually the obtained strain maps are used to identify the elastic parameters with the Virtual Fields Method (VFM). The numerical errors propagating through the simulation procedure are carefully characterized. Besides, the simulator is used to compare the performances of DIC and the grid method in the identification process with the VFM. Finally, the influence of DIC settings on the identification error is studied as a function of the camera digital noise level, in order to find the best testing configuration. [ABSTRACT FROM AUTHOR]

Attitude determination is one of the key technologies for Attitude Determination and Control System (ADCS) of a satellite. However, serious model errors may exist which will affect the estimation accuracy of ACDS, especially for a small satellite with low precision sensors. In this paper, a central difference predictive filter (CDPF) is proposed for attitude determination of small satellites with model errors and low precision sensors. The new filter is proposed by introducing the Stirling’s polynomial interpolation formula to extend the traditional predictive filter (PF). It is shown that the proposed filter has higher accuracy for the estimation of system states than the traditional PF. It is known that the unscented Kalman filter (UKF) has also been used in the ADCS of small satellites with low precision sensors. In order to evaluate the performance of the proposed filter, the UKF is also employed to compare it with the CDPF. Numerical simulations show that the proposed CDPF is more effective and robust in dealing with model errors and low precision sensors compared with the UKF or traditional PF. [ABSTRACT FROM AUTHOR]

In this paper, we propose nonpolynomial and Hermite nonpolynomial interpolation with multiple parameters and present method to determine optimal value of parameters which generate minimum error in approximation. The generalized error analysis results for nonpolynomial and Hermite nonpolynomial interpolations are derived. We establish theoretical relationship among nonpolynomial, polynomial interpolation and the Fourier series, and propose solution to Runge’s phenomenon through nonpolynomial interpolation. The Hermite nonpolynomial cubic spline, nonpolynomial cubic spline interpolation methods and their error analysis are presented. Numerical simulations are carried out for the analysis of error in cubic spline interpolations. Proposed method is applied to the analysis of various time series to show comparison in errors between polynomial and nonpolynomial spline interpolations, and to Empirical Mode Decomposition (EMD) to illustrate practical usefulness of the results. [ABSTRACT FROM AUTHOR]

This paper compares performances of frequency estimations provided by different interpolation fast Fourier transform (FFT) algorithms under white Gaussian noises. Firstly, accuracies of frequency estimation algorithms are evaluated by deriving analytical expressions of variances of frequency estimation. Then, theoretical results are validated by means of computer simulations. It is shown that the trade-off between biases and variances of frequency estimation is unavoidable. From both theoretical and simulation results, it can be concluded that variances of frequency estimation are proportional to the noise variance and inverse proportional to the length of FFT. [ABSTRACT FROM AUTHOR]

In this paper, a bilinear interpolation finite-difference scheme is proposed to handle the Neumann boundary condition with nonequilibrium extrapolation method in the thermal lattice Boltzmann model. The temperature value at the boundary point is obtained by the finitedifference approximation, and then used to determine the wall temperature via an extrapolation. Our method can deal with the boundaries with complex geometries, motions and gradient boundary conditions. Several simulations are performed to examine the capacity of this proposed boundary method. The numerical results agree well with the analytical solutions. When compared with a representative boundary method, an improved performance is observed. The results also show that the proposed scheme together with nonequilibrium extrapolation method has second-order accuracy. [ABSTRACT FROM AUTHOR]

This paper presents a family of numerical solvers for anisotropic subdiffusion problems in annuli and also cylindrical and spherical shells. The fractional order Caputo temporal derivative is discretized based on linear interpolation. The spatial Laplacian is discretized by utilizing Chebyshev and Fourier spectral collocation. Detailed discussion and useful formulas are presented for polar, cylindrical, and spherical coordinate systems. Numerical experiments along with a brief analysis are presented to demonstrate the accuracy and efficiency of these solvers. These solvers represent a continuation of our work in Tan and Liu (2020) and shall be useful for numerical simulations of subdiffusion problems in cellular cytoplasm and other similar settings. [ABSTRACT FROM AUTHOR]

Models of the gas exchange process in modern diesel engines typically use manufacturer-provided maps to describe mass flows through, and efficiencies of, the turbine and compressor based on pressure ratios across the turbine and compressor, as well as the turbocharger shaft speed, and in the case of variable-geometry turbochargers, the nozzle position. These look-up maps require multiple interpolations to produce the necessary information for turbocharger performance, and are undesirable when modeling for estimation and control. There have been several previous efforts to reduce dependence on maps with general success, yet many of these approaches remain complex and are not easily integrated into engine control systems. The focus of this paper is the reduction of turbomachinery maps to analytical functions that are amenable to estimator and control design, and have been validated against manufacturer-provided turbomachinery data. [ABSTRACT FROM AUTHOR]

Root raised cosine roll-off (RRC) filter is one of the most fundamental elements in modern digital communications. This paper proposes a new method to efficiently realize the RRC filter. The method employs cubic Hermite interpolation to obtain a piecewise-polynomial approximation for the impulse response of the RRC filter. Then, the approximated impulse response is efficiently realized by using a transversal filter with a very small number of taps followed by integrators with a simple recursive structure, named cascaded recursive finite impulse response (CR-FIR) filter. As an example, an RRC filter with roll-off factor 0.5 is constructed by using the CR-FIR filter with only nine multipliers. Performance of the RRC filter in matched filtering is examined by computer simulations. Then, it is shown that the constructed RRC matched filter has nearly the same performance as the ideal filter. [ABSTRACT FROM AUTHOR]