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The sum–difference coarray is the union of difference coarray and the sum coarray, which is capable to obtain a higher number of degrees of freedom (DOF) than the difference coarray. However, this method fails to use all information provided by the coprime array because of the existence of holes. In this paper, we introduce the virtual array interpolation into the sum–difference coarray domain. After interpolating the virtual array, we estimate the DOA by reconstructing the covariance matrix to resolve an atomic norm minimization problem in a gridless way. The proposed method is gridless and can effectively utilize the DOF of a larger virtual array. Numerical simulation results verify the effectiveness and the superior performance of the proposed algorithm. [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]

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]

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]

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]

This paper presents a context-aware computer aided inbetweening (CACAI) technique that interpolates planar strokes to generate inbetween frames from a given set of key frames. The inbetweening is context-aware in the sense that not only the stroke’s shape but also the context (i.e., the neighborhood of a stroke) in which a stroke appears are taken into account for the stroke correspondence and interpolation. Given a pair of successive key frames, the CACAI automatically constructs the stroke correspondence between them by exploiting the context coherence between the corresponding strokes. Meanwhile, the construction algorithm is able to incorporate the user’s interaction with ease and allows the user more effective control over the correspondence process than existing stroke matching techniques. With a one-to-one stroke correspondence, the CACAI interpolates the shape and context between the corresponding strokes for the generation of intermediate frames. In the interpolation sequence, both the shape of individual strokes and the spatial layout between them are well retained such that the feature characteristics and visual appearance of the objects in the key frames can be fully preserved even when complex motions are involved in these objects. We have developed a prototype system to demonstrate the ease of use and effectiveness of the CACAI. [ABSTRACT FROM AUTHOR]

The classical interpolation-based Polar Format Algorithm (PFA) for spotlight synthetic aperture radar (SAR) results in numerous computation load, which, reduces processing speed and increase system complexity. To decrease computation load, this paper proposes a novel non-interpolation PFA algorithm for sensor flying along non-lineal flight trajectories, which are specially designed curves in conical surface. Then an innovative auto-adaptive Pulse Repetition Frequency (PRF) technique is put forward to uniformly sample signal in azimuth direction. The computation load of the new PFA is merely left to azimuth chirp z-transforms (CZTs) and range fast Fourier transforms (FFTs) after dechirp processing and residual video phase (RVP) compensation. Two flight modes (ellipse trajectory mode and hyperbola trajectory mode) are analyzed. A lineal approximation method is proposed to simplify non-lineal sensor trajectory analysis. Computer simulation results for multiple point targets validate the presented approach. Comparison of computation load between this PFA and traditional PFA is represented in Appendix B. [ABSTRACT FROM AUTHOR]

As minimally invasive surgical techniques become widely known to patients, medical training systems based on virtual simulation are highly desired. These systems help surgeon trainees to acquire, practice and evaluate their surgical skills. A key component in a virtual training system is to simulate the dynamics that occur in surgical procedures. Tissue cutting, as a common phenomenon during surgery, has attracted many research efforts in computer simulation. In this paper, we propose an approach to endoscopic image cutting simulation which is based on both mass-spring model and Computational Geometry. In the cutting simulation model, the springs to be cut off are imagined into line segments. In the calculation of the elastic force on mass points, we have found that whether some adjacent springs of a mass point to be eliminated or not during a cutting is critical. If a spring intersects the cutting plane, we set the elastic force of this spring to zero. We adopted properties of cross product and related algorithms (the rapid exclusion test, the crossover test) in Computational Geometry to determine the springs that are intersected with the cutting plane. And then, we utilized the bilinear interpolation and OpenGL techniques to render the cutting procedure of the soft tissue. The experimental results show that our cutting simulation is effective and practical. [ABSTRACT FROM AUTHOR]

Time delay estimation (TDE) lies at the heart of signal processing algorithms in a broad range of application areas, including communications, coherent imaging, speech processing, and acoustics. In medical ultrasound for example, TDE is used in blood flow estimation, tissue motion measurement, tissue elasticity estimation, phase aberration correction, and a number of other algorithms. Because of its central significance, TDE accuracy, precision, and computational cost are of critical importance. Furthermore, because TDE is typically performed au sampled signals—and delay estimates are usually desired over a continuous domain—time delay estimator performance should be considered in conjunction with associated interpolation. In this paper we present a new time-delay estimator that directly determines continuous time-delay estimates from sampled data. The technique forms a spline-based, piecewise continuous representation of the reference signal then solves for the minimum of the sum squared error between the reference and the delayed signals to determine their relative time delay. Computer simulation results clearly show that the proposed algorithm significantly outperforms other algorithms in terms of jitter and bias over a broad range of conditions. We also describe a modified version of the algorithm that includes companding with only a minor increase in computational cost. [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]

Contemporary land information systems allow the generation of models of numerical surfaces by applying a number of interpolation algorithms. The appropriate selection of measurement points included in the calculations is one of the key factors influencing the quality and accuracy of interpolation. Properly selected points contribute to improving the accuracy of the generated surface models and to shortening the computation process. This paper analyzes the effect of the location and density of measurement points on the accuracy of interpolation surfaces in view of the morphological differentiation of the generated models. [ABSTRACT FROM AUTHOR]

As a novel tool for quantitative 3D internal deformation measurement throughout the interior of a material or tissue, digital volume correlation (DVC) has increasingly gained attention and application in the fields of experimental mechanics, material research and biomedical engineering. However, the practical implementation of DVC involves important challenges such as implementation complexity, calculation accuracy and computational efficiency. In this paper, a least-squares framework is presented for 3D internal displacement and strain field measurement using DVC. The proposed DVC combines a practical linear-intensity-change model with an easy-to-implement iterative least-squares (ILS) algorithm to retrieve 3D internal displacement vector field with sub-voxel accuracy. Because the linear-intensity-change model is capable of accounting for both the possible intensity changes and the relative geometric transform of the target subvolume, the presented DVC thus provides the highest sub-voxel registration accuracy and widest applicability. Furthermore, as the ILS algorithm uses only first-order spatial derivatives of the deformed volumetric image, the developed DVC thus significantly reduces computational complexity. To further extract 3D strain distributions from the 3D discrete displacement vectors obtained by the ILS algorithm, the presented DVC employs a pointwise least-squares algorithm to estimate the strain components for each measurement point. Computer-simulated volume images with controlled displacements are employed to investigate the performance of the proposed DVC method in terms of mean bias error and standard deviation error. Results reveal that the present technique is capable of providing accurate measurements in an easy-to-implement manner, and can be applied to practical 3D internal displacement and strain calculation. [ABSTRACT FROM AUTHOR]

In this paper, we propose a high-resolution autoregressive moving average (ARMA) modeling technique for signals which are a sum of sinusoids embedded in colored noise. The approach is based on a special ARMA model. We show that an approximation to this model can be found through the central solution of Nevanlinna-Pick interpolation. In this context, it can reach a very fine resolution with a special arrangement of filterbank poles. A very efficient iterative algorithm will then be presented to achieve such desired arrangement. We also derive theoretical expressions for the variance of interpolation values for both continuous and mixed spectra for complex poles. Computer simulations show that the approach is very powerful in joint power spectrum and frequency estimation and provides superior performance with respect to traditional techniques. [ABSTRACT FROM AUTHOR]

This paper addresses the problem of modeling systems from measurements of their frequency response. For multiport devices, currently available techniques are expensive. We propose a new approach which is based on a system-theoretic tool, the Loewner matrix pencil constructed in the context of tangential interpolation. Several implementations are presented. They are fast, accurate, they build low order models and are especially designed for a large number of terminals. Moreover, they identify the underlying system, rather than merely fitting the measurements. The numerical results show that our algorithms yield smaller models in less time, when compared to vector fitting. [ABSTRACT FROM AUTHOR]

Symbol timing offset (STO) can result in intersymbol interference (ISI) and a rotated phase which value is proportional to the subcarrier index at the FFT output in an OFDM receiver. In order to avoid ISI, the FFT window start position has to be put in advance of the estimated point obtained by coarse STO estimation algorithms. But a large number of forward-shift samples will deteriorate the estimation of data subcarrier channels requiring interpolation from pilot subcarrier channels due to the phase rotation caused by a residual STO. In this paper we analyze the influence of STO on channel interpolation and propose a new compensation method for channel correction with STO. From the performance analysis of simulation results in the DVB-T application, the new algorithm not only has a better performance but also is attractive in using a simple residual STO estimation method such that few pilots are required for fine STO estimation compared to conventional approaches. [ABSTRACT FROM AUTHOR]

Reconstruction of freeform surfaces from scattered coordinate data is a difficult problem encountered in many surface fitting and geometric modeling applications. Conventional tessellation and parametric surface fitting techniques are limited because they require prior knowledge about the connectivity between the sampled points. The method of surface reconstruction described in this paper exploits the learning capability of a self-organizing feature map (SOFM) to adaptively fit a deformable sphere to the unorganized 3D coordinate data. The learning algorithm automatically establishes the connectivity between the measured points by iteratively changing the topological relationships within the map. By incorporating additional constraints during the learning process it is possible to have the deformable map follow the shape of objects with surface holes and cavities. Several examples of freeform surfaces with varying levels of complexity are discussed in order to demonstrate the performance of the algorithm. [ABSTRACT FROM AUTHOR]

A new non-linear view interpolation algorithm is presented in this paper. Unlike the linear interpolation scheme, our method can exactly simulate the perspective viewing transformation during walkthrough. To accelerate the view interpolation, the algorithm employs a binary subdivision scheme to optimize the decomposition of the source image so that the number of resultant blocks is greatly reduced. Holes in the intermediate image are filled by two steps, namely enlarging the transferred blocks at the sides adjacent to holes and retrieving the local image within holes from the destination images by multidirectional interpolation. Experimental results demonstrate that our algorithm is much more accurate and efficient than the traditional one. Copyright © 1999 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

We propose the reconstruction algorithm for two-step parallel phase-shifting digital holography. Parallel phase-shifting digital holography records a single hologram and numerically extracts the multiple images needed for obtaining the complex amplitude in phase-shifting technique. During the reconstruction process, phase error and degradation of image occur due to the calculation error. The proposed algorithm interpolates into two steps that include the subpixel data to reduce the error, so the quality that a reconstructed image can be enhanced. Both numerical simulation and experiment are conducted to verify the effectiveness of the proposed algorithm. [ABSTRACT FROM PUBLISHER]

We examine the problem of interpolating antenna radiation patterns from a small number of measurements and propose an algorithm to perform the interpolation when naïve methods fail, often due to multipath corruption of the pattern. This algorithm exploits constraints on the antenna's underlying design to avoid ambiguities but is sufficiently general to address many different antenna types. A theoretical basis for the robustness of this algorithm is developed, and its performance is verified in simulation using a number of popular antenna designs and with a controlled laboratory experiment. [ABSTRACT FROM AUTHOR]

With regard to skeletal character animation, the question on how to ensure the quality of transition between key frames is of crucial importance. The lack of properly defined motion ranges based on movements would leave the animator with no choice but intervene the result based on camera perspective afterwards, thus creating a lot more work for the animator to modify or clean up the animation curves. Although a number of methods have been raised in these years, such as the Linear Blending Skinning (LBS), they may still have shortcomings in some specific cases, one of which is the obvious unnatural deformation around the joint areas. The primary investigation in this paper is directed to address the problem and improve the framework of rendering in real-time environment with satisfactory skinning effect to the aforementioned scenario, with assistance of GPU computation. [ABSTRACT FROM AUTHOR]

In this paper, we present a new approach of-spline curve fitting to a set of ordered points, which is motivated by an insight that properly selected points called dominant points can play an important role in producing better curve approximation. The proposed approach takes four main steps: parameterization, dominant point selection, knot placement, and least-squares minimization. The approach is substantially different from the conventional approaches in knot placement and dominant point selection. In the knot placement, the knots are determined by averaging the parameter values of the dominant points, which basically transforms-spline curve fitting into the problem of dominant point selection. We describe the properties of the knot placement including the property of local modification useful for adaptive curve refinement. We also present an algorithm for dominant point selection based on the adaptive refinement paradigm. The approach adaptively refines a-spline curve by selecting fewer dominant points at flat regions but more at complex regions. For the same number of control points, the proposed approach can generate a-spline curve with less deviation than the conventional approaches. When adopted in error-bounded curve approximation, it can generate a-spline curve with far fewer control points while satisfying the desired shape fidelity. Some experimental results demonstrate its usefulness and quality. [Copyright &y& Elsevier]

Proposes a binary morphological morphing approach for interpolation applied to three-dimensional tooth reconstruction. Description of the morphological morphing transformation; Overview of the interpolation algorithm; Experimental results of the application of algorithm for reconstructing the shape of various teeth from slices.

An algorithm is presented for the estimation of molecular properties over a library built around a scaffold, which has N sites for functionalization with M moieties at the ith scaffold site, corresponding to a library of $${\prod_{i=1}^N M_i}$$ molecules. The algorithm relies on a series of operations involving (i) synthesis and property measurement of a minimal number of T randomly sampled members of the library, (ii) expression of the observed property in terms of a high-dimensional model representation (HDMR) of the moiety → property map, (iii) optimization of the ordered sequence of moieties on each site to regularize the HDMR map and (iv) interpolation using the map to estimate the properties of as yet unsynthesized compounds. The set of operations is performed iteratively aiming to reach convergence of the predictive HDMR map with as few synthesized samples as possible. Through simulation, the number T of required random molecular samples is shown to scale very favorably with $${T < < \prod^N_{i=1} M_i}$$ for cases up to N = 20 and M = 20. For example, high estimation quality was attained for simulated libraries with T ~ 5,000 sampled compounds for a library of 20 members and T ~ 12,500 sampled compounds for a library of 20 members. The algorithm is based on the assumption that a systematic pattern exists in the moiety → property map provided that the moieties are optimally ordered on the scaffold sites within the context of HDMR. The overall procedure is referred to as the substituent reordering HDMR algorithm (SR-HDMR). The technique was also successfully tested with laboratory data for estimating C-NMR shifts in a tri-substituted benzene library and for lac operon repression binding. [ABSTRACT FROM AUTHOR]

The interframe interpolation method presented consists of partial changing, using the growing size of structuring elements, of the morphological skeleton decomposition subsets of a binary input or grayscale frame with the morphological skeleton decomposition subsets of a binary output or grayscale frame. One of the interpolated frames obtained by this method is similar to the reference frame. Computer simulations illustrate the results. [ABSTRACT FROM AUTHOR]

During the last decade, radar imaging has been used in near-field scenarios where a cylindrical scan geometry is required to properly illuminate the scan region, such as breast microwave radar imaging and microwave wood inspection. Nevertheless, current cylindrical near-field radar image formation algorithms are not fast enough to provide the throughput required by these novel applications. A real-time wavefront reconstruction approach for the formation of three-dimensional cylindrical near-field radar images is proposed in this study. This technique parallelises the mapping procedures during the reconstruction process in order to increase its computational efficiency. To further reduce the execution time of the proposed approach, it was implemented in a general purpose graphic processing unit in order to take advantage of the computing capabilities of this platform. The proposed method yielded accurate results when applied to simulated and experimental data sets and yielded speed improvements of two orders of magnitude compared to conventional cylindrical near-field radar reconstruction approaches. [ABSTRACT FROM AUTHOR]

In this brief, we present a low-jitter and wide-range all-digital phase-locked loop (ADPLL). This ADPLL achieves low output clock jitter by a number of schemes. First, the phase is locked quickly through a predictive phase-locking scheme. Then, the jitter is further reduced by a suppressive digital loop filter. Finally, an interpolation-based locking scheme is utilized to enhance the resolution of the digitally controlled oscillator (DCO) so as to further reduce the phase error and jitter. Simulation results show that the jitter performance is very close to that of the free-running DCO. Measurement results show that the jitterPk\mathchar "702DPk and jitterRMS are 56 and 7.28 ps, respectively, when the output clock of the ADPLL is running at 600 MHz. [ABSTRACT FROM AUTHOR]

We present an adaptive subdivision scheme for unstructured tetrahedral meshes inspired by the -subdivision scheme for triangular meshes. Existing tetrahedral subdivision schemes do not support adaptive refinement and have traditionally been driven by the need to generate smooth three-dimensional deformations of solids. These schemes use edge bisections to subdivide tetrahedra, which generates octahedra in addition to tetrahedra. To split octahedra into tetrahedra one routinely chooses a direction for the diagonals for the subdivision step. We propose a new topology-based refinement operator that generates only tetrahedra and supports adaptive refinement. Our tetrahedral subdivision algorithm is motivated by the need to have one representation for the modeling, the simulation and the visualization and so to bridge the gap between CAD and CAE. Our subdivision algorithm design emphasizes on geometric quality of the tetrahedral meshes, local and adaptive refinement operations, and preservation of sharp geometric features on the boundary and in the interior of the physical domain. [ABSTRACT FROM AUTHOR]

Iterative image reconstruction algorithums play an increasingly important role in modem tomographic systems, especially in emission tomography. With the fast increase of the sizes of the tomographic data, reduction of the computation demands of the reconstruction algorithms is of great importance. Fourier-based forward and back-projection methods have the potential to considerably reduce the computation time in iterative reconstruction. Additional substantial speed-up of those approaches can be obtained utilizing powerful and cheap off-the-shelf fast Fourier transform (FFT) processing hardware. The Fourier reconstruction approaches are based on the relationship between the Fourier transform of the image and Fourier transformation of the parallel-ray projections. The critical two steps are the estimations of the samples of the projection transform, on the central section through the origin of Fourier space, from the samples of the transform of the image, and vice versa for back-projection. Interpolation errors are a limitation of Fourier-based reconstruction methods. We have applied mm-max optimized Kaiser-Bessel interpolation within the nonuniform FFT (NUFFT) framework and devised ways of incorporation of resolution models into the Fourier-based iterative approaches. Numerical and computer simulation results show that the min-max NUFFT approach provides substantially lower approximation errors in tomographic forward and back-projection than conventional interpolation methods. Our studies have further confirmed that Fourier-based projectors using the NUFFT approach provide accurate approximations to their space-based counterparts but with about ten times faster computation, and that they are viable candidates for fast iterative image reconstruction. [ABSTRACT FROM AUTHOR]