Direct Interpolation Algorithm Research Articles

Dynamic Monitoring and Vibration Analysis of Ancient Bridges by Ground-Based Microwave Interferometry and the ESMD Method

In this paper, we propose to conduct a dynamic monitoring and vibration analysis of ancient bridges by means of ground-based microwave interferometry and the extreme-point symmetric mode decomposition (ESMD) method. Ground-based microwave interferometry, a novel non-contact technology with a high accuracy, is used to acquire dynamic time series displacements with environmental excitation factors and a transient load with a car, respectively. The ESMD method, a new alternative to the Hilbert-Huang transform (HHT), is adopted to conduct the instantaneous vibration analysis of Zhaozhou Bridge. Firstly, a series of intrinsic mode functions (IMFs) are obtained together with an optimal adaptive global mean (AGM) curve by using a mode symmetric about the maxima and minima points. Secondly, the instantaneous frequency of each IMF is obtained by the use of a direct interpolation algorithm, which can reconcile the conflict between the period and the frequency for the traditional time-frequency analysis methods. As a representative case, Zhaozhou Bridge, a well-known Chinese ancient bridge constructed more than 1400 years ago, is studied in detail. Four kinds of dynamic time series displacements—two of them acquired by considering only environmental excitation factors for the mid-span and 1/4-span points and the others obtained with the transient load of a car for the mid-span and 1/4-span points—are selected to pursue a comparison of the decomposed IMFs and the instantaneous frequencies to perform the instantaneous vibration analysis of Zhaozhou Bridge. By comparing the results obtained with HHT for the decomposed IMFs and the instantaneous frequencies, the results show that the proposed method has a powerful ability to evaluate the instantaneous dynamic response of ancient bridges.

An Effective Directional Residual Interpolation Algorithm for Color Image Demosaicking

In this paper, we propose an effective directional Bayer color filter array (CFA) demosaicking algorithm based on residual interpolation (RI). The proposed directional interpolation algorithm aims to reduce computational complexity and get more accurate interpolated pixel values in the complex edge areas. We use the horizontal and vertical weights to combine and smooth color difference estimations. Compared with four directional weights in minimized Laplacian residual interpolation, the proposed algorithm not only guarantees the quality of color images but also reduces the computational complexity. Generally, the directional estimations may be inaccurately calculated because of the false edge information in irregular edges. We alleviate it by using a new method to calculate the directional color difference estimations. Experimental results show that the proposed algorithm provides outstanding performance compared with some previous algorithms, especially in the complex edge areas. In addition, it has lower computational complexity and better visual effect.

ESMD-based stability analysis in the progressive collapse of a building model: A case study of a reinforced concrete frame-shear wall model

Aiming to estimate the degree of damage influences on a building model, this paper proposes to adopt the extreme-point symmetric mode decomposition (ESMD) method to conduct a stability analysis in the progressive collapse of a building model. As a representative case, a five-story reinforced concrete frame-shear wall building model with a destructible glass wall, is studied in detail. The input signals of key locations on the building model are obtained by high-speed videogrammetry (HSV). First, the original complex response signal is decomposed into a series of simple signals called intrinsic mode functions (IMFs) by a mode symmetric about the maxima and minima points. Second, the instantaneous frequency of each IMF is obtained to perform a stability analysis by a direct interpolation (DI) algorithm. Third, instantaneous energy is obtained to conduct a stress analysis for the key locations of the building model. The results demonstrate that the proposed method has an ability to perform a stability analysis in the progressive collapse of a building model efficiently.

Error correction based on micro-scanning preprocessing for an optical micro-scanning thermal microscope imaging system

In recent years, various thermal microscope imaging systems have been developed to meet the demands of micro-thermal analysis for large-scale integrated circuits, biomedical, science, and research fields. However, conventional thermal microscope imaging systems, which use cooled infrared detectors are heavy and expensive. In order to solve this problem, we developed a thermal microscope imaging system based on an uncooled infrared detector. However, the spatial resolution of the thermal microscope imaging system based on an uncooled infrared detector is low. With optical micro-scanning technology, the spatial resolution of the thermal microscope imaging system can be increased without increasing the detector dimension or reducing the detector unit size. In order to improve its spatial resolution, a micro-scanning system based on optical plate rotation was developed, and an optical microscanning thermal microscope imaging system was obtained after the integrated design. Due to environmental factors, mechanical vibration, alignment error and other factors, there is micro-scanning error in the designed micro-scanning thermal microscope imaging system. The four low-resolution images collected by micro-scanning thermal microscope imaging system are not standard down-sampled images. The quality of the image interpolated directly by four collected images is reduced and the performance of the micro-scanning system isn’t fully exploited. Therefore, based on the proposed second-order oversampling reconstruction micro-scanning error correction algorithm and the new edge directed interpolation algorithm, a new micro-scanning error correction technique is proposed. Simulations and experiments show that the proposed technique can effectively reduce optical micro-scanning error, improve the systems spatial resolution and optimize the effect of the imaging system. It can be applied to other electro-optical imaging systems to improve their spatial resolution.

A High-Speed Directional Image Interpolation Algorithm Based-on the Analysis of Wavelet and Edge Patterns

A High-Speed Directional Image Interpolation Algorithm Based-on the Analysis of Wavelet and Edge Patterns

A Fast Directional Image Interpolation Algorithm Based on RDWT Concept

A Fast Directional Image Interpolation Algorithm Based on RDWT Concept

Design Modeling and Simulation by Interpolation Algorithm of Zadoff-Chu Sequence

HF channel sounding requires perfect autocorrelation property of the sounding sequences. Compared with other pseudonoise sounding sequences, Zadoff-Chu sequence gets great attention due to its predominant periodic autocorrelation property. In order to adapt the spectrum property of Zadoff-Chu sequence to the requirement of HF channel sounding transmitter-receiver, the Formula Direct Interpolation Algorithm (FDIA) is put forward by which the amplitude frequency characteristic of Zadoff-Chu sequence can be enhanced. Application examples show that, this system can significantly improve the efficiency of aerodynamic design.

Interpolation Algorithm Application of Zadoff-Chu Sequence Using Neural Networks

In order to adapt the spectrum property of Zadoff-Chu sequence to the requirement of HF channel sounding transmitter-receiver, the Formula Direct Interpolation Algorithm (FDIA) is put forward by which the amplitude frequency characteristic of Zadoff-Chu sequence can be enhanced. Then the comparison of spectra of the sequences respectively interpolated by FDIA and commonly used interpolation algorithm is conducted, which affirms the superiority of FDIA. Finally, an effective method of achieving best decimation of the sequence interpolated by FDIA is provided. All these lay primary theory foundation for the application of Zadoff-Chu sequence to HF channel sounding.

Direct Interpolation of Tool Orientation in 5-Axis Milling

By circumference milling with 5-axis machine or machining center has quite the machining efficiency and the surface quality of the products been improved. But when inclined inside surface of cavity is circumference milled with the default linear interpolation of rotation angle algorithm, it results in a serious non-linear error, which takes on over cutting or under cutting, e.g. the inclined plane will be over milled by the machine with dual swivel-head machining center. In order to resolve this problem, the direct interpolation algorithm of tool orientation is developed after analyzing the algorithm of linear interpolation of rotation angles and its non-linear error is. The algorithm is reported and tested with the object of a machine with AB-axis swivel head. The testing results proved that it can resolve the problem of non-linear error.

A Novel Trajectory Control Algorithm for Intersection Seam Automated Welding

A saddle-shaped curve is formed by intersection of two tubes. This paper proposes a new saddle curve interpolation algorithm for automated welding system with non-Cartesian coordinate system. The trajectory interpolation of saddle-shaped curve is usually carried out through approximating the curve as segments of straight line/circular arc for intersection seam automated CNC welding. Simulation of the direct interpolation algorithm is carried out to testify its effectiveness and superiority. With this algorithm, it is demonstrated that the chord error is within the allowable limits and the algorithm has high reliability.

A Novel CNC Interpolation Algorithm for Saddle Curve

This paper presents an efficient and accurate direct interpolation algorithm for saddle curve formed by intersection of two tubes, an important manufacturing problem in automated welding/cutting field. The algorithm is able to directly interpolate the saddle curve with non-Cartesian configuration. Simulation of the saddle curve interpolation algorithm has been carried out on the Matlab platform. The results demonstrate that interpolation error is well within the accuracy requirements of typical machining. It also shows that the trajectory control program based on the algorithm can work with high efficiency.

Trajectory Control in Automated Welding of Tubular Joints

A saddle curve is formed by intersection of two tubes. The trajectory control of saddle curve is usually carried out through approximating the curve as segments of straight line/circular arc for CNC interpolation. Based on the principle of space analytic geometry, this paper proposes a new trajectory control approach to directly interpolate the saddle curve for automated welding/cutting system. Simulation of the direct interpolation algorithm of saddle curve has been carried out to verify the effectiveness of the proposed algorithm. It also demonstrates that the interpolation error is well within the accuracy requirements and the proposed algorithm is potentially useful for the cutting/welding of saddle curve of tubular joints.

Directional View Interpolation for Compensation of Sparse Angular Sampling in Cone-Beam CT

In flat detector cone-beam computed tomography and related applications, sparse angular sampling frequently leads to characteristic streak artifacts. To overcome this problem, it has been suggested to generate additional views by means of interpolation. The practicality of this approach is investigated in combination with a dedicated method for angular interpolation of 3-D sinogram data. For this purpose, a novel dedicated shape-driven directional interpolation algorithm based on a structure tensor approach is developed. Quantitative evaluation shows that this method clearly outperforms conventional scene-based interpolation schemes. Furthermore, the image quality trade-offs associated with the use of interpolated intermediate views are systematically evaluated for simulated and clinical cone-beam computed tomography data sets of the human head. It is found that utilization of directionally interpolated views significantly reduces streak artifacts and noise, at the expense of small introduced image blur.

Algorithms for subpixel registration

This paper presents an analysis of four algorithms which are able to register images with subpixel accuracy; these are correlation interpolation, intensity interpolation, differential method, and phase correlation. The subpixel registration problem is described in detail and the resampling process for subpixel registration is analyzed theoretically. It is shown that the main factors affecting registration accuracy are the interpolation function, sampling frequency, number of bits per pixel, and frequency content of the image. An iterative version of the intensity interpolation algorithm, which achieves maximum computational efficiency, is also presented. Analyses, computer simulations, and experiments for measuring displacements of objects using their speckle images have shown that this algorithm is faster than a direct intensity interpolation algorithm by a factor of more than ten thousand. Using bilinear interpolation and representing pixels by 8-bit samples, a 0.01 to 0.05 pixel registration accuracy can be achieved.