Abstract To address the issue of invalid values in the measured wind speed data of the wind lidar, a data interpolation experiment was conducted by using the wind speed data outputted by the wind ...lidar as the base data source. Based on data preprocessing, the interpolation model was constructed by integrating MLP and the mean wind speed shear index. The accuracy of the interpolated wind speed data was evaluated. The experimental results show that the proposed interpolation method for wind lidar data achieved high accuracy, with a root mean square error of less than 0.75 m/s and an average relative error of less than 3.5%. This approach enhances the reliability and integrity of wind lidar data, providing a reference for the use of wind lidar data in wind resource assessment.
To generate continuous velocity, acceleration and jerk curves of parametric interpolation in high-speed and high-accuracy machining, this paper presents a trigonometric velocity scheduling algorithm ...based on two-time look-ahead interpolation (pre-interpolation and look-ahead interpolation). The algorithm consists of three modules: pre-interpolation, look-ahead interpolation and real-time interpolation. The pre-interpolation module aims to explore and record the information of the path to be machined. The look-ahead interpolation module firstly calculates the velocity scheduling functions according to the data recorded by pre-interpolation, and then tests and adjusts the feedrate scheduling schemes constantly. The real-time interpolation module adapts the method of beforehand deceleration or delaying acceleration according to the signals received from pre-interpolation and look-ahead interpolation to guarantee the processing accuracy. Simulation and experimental tests demonstrate the availability, effectiveness and advantages of the trigonometric velocity scheduling algorithm. And the proposed trigonometric velocity scheduling algorithm based on pre-interpolation and look-ahead interpolation could realize smooth velocity, acceleration and jerk control with restricted chord error and implement high-quality CNC processing.
•A trigonometric velocity scheduling algorithm based on two-time look-ahead interpolation is proposed.•The velocity scheduling algorithm could provide continuous velocity, acceleration and jerk curves.•The pre-interpolation explores the path to be machined and classifies the path into three situations.•The look-ahead interpolation designs and adjusts the feedrate scheduling scheme constantly.•We adapt the methods of beforehand deceleration and delaying acceleration to guarantee the processing accuracy.
A 6-bit 2.5-GS/s Formula Omitted dynamic interpolating flash analog-to-digital converter (ADC) with an offset calibration technique for interpolated voltage-to-time converters (VTCs) is presented for ...high-speed applications. The dynamic-amplifier-structured VTC enables linear zero-crossing (ZX) interpolation in the time domain with an interpolation factor of 8, which reduces the number of front-end VTCs to one-sixth the original structure. The reduced number of VTCs lowers the power consumption, load capacitance to the track-and-holder (T/H), and overhead of VTC offset calibration. The sequential slope-matching offset calibration scheme is proposed not only for VTC offset but also for interpolated ZX accuracy. The prototype 6-bit 2.5-GS/s flash ADC was implemented in a 65-nm CMOS process and occupies a 0.12 mm2 chip area, including offset calibration circuitry. The measured differential non-linearity (DNL) and integral non-linearity (INL) after offset calibration are 0.68 and 0.65 LSB, respectively. With a 1.23 GHz input, the measured signal-to-noise and distortion ratio (SNDR) and spurious-free dynamic range (SFDR) are 33.84 and 45.07 dB, respectively, with power consumption of 7.5 mW under a supply voltage of 0.85 V. The prototype ADC achieves a figure of merit (FoM) of 74.7 fJ/conversion step at 2.5 GS/s.
A new generalization of multiquadric functions φ(x)=c2d+||x||2d, where x∈Rn, c∈R, d∈N, is presented to increase the accuracy of quasi-interpolation further. With the restriction to Euclidean spaces ...of odd dimensionality, the generalization can be used to generate a quasi-Lagrange operator that reproduces all polynomials of degree 2d−1. In contrast to the classical multiquadric, the convergence rate of the quasi-interpolation operator can be significantly improved by a factor h2d−n−1, where h>0 represents the grid spacing. Among other things, we compute the generalized Fourier transform of this new multiquadric function. Finally, an infinite regular grid is employed to analyse the properties of the aforementioned generalization in detail. We also present numerical results to demonstrate the advantages of our new multiquadric functions.
Image sequence interpolation is a critical research area in computer vision with broad applications in video frame interpolation and medical image interlayer interpolation. Traditional deep ...learning-based methods in this domain predominantly rely on deep convolutional neural networks (CNNs), which, despite their effectiveness, are limited by the inherent constraints of CNN architecture, impacting their interpolation accuracy. To address these limitations, we introduce the Pre-ISIformer, a parallel multi-channel adaptive image sequence interpolation network founded on pre-trained transformers. This innovative network is composed of three integral modules: 1) Global feature extraction module is designed to extract primary features from the input images using a pre-trained Swin-transformer model, ensuring comprehensive global feature coverage. 2) Feature sequence construction module adaptively decomposes the object's motion path across different frames, facilitating a detailed analysis of motion dynamics. And 3) Intermediate image reconstruction module is responsible for accurately capturing target displacements. Furthermore, we incorporate distinct metrics for pixel loss and gradient loss to meticulously reconstruct the texture and contours of the intermediate images. Our network has been rigorously tested on various datasets for two primary applications: video frame interpolation and interlayer interpolation in medical imaging. The results from these experiments showcase the superior performance and effectiveness of the Pre-ISIformer, establishing it as a significant advancement in the field of image sequence interpolation.
Abstract The escalation in the risk of extreme weather events due to climate system warming has caused a distinct alteration in the frequency and intensity of cold waves in China. Moreover, these ...changes exhibit distinct regional variations in their altering characteristics. Using daily temperature data from 70 weather stations in Fujian Province of China from 1961 to 2018, this study looks at how cold waves move through the province and how they change over time. It does this by combining linear regression trend, spatial interpolation, and spatial autocorrelation analyses. The findings indicate that the occurrence frequency of cold waves in the designated study area is notably higher in the western and northern regions, while it is comparatively lower in the eastern coastal cities. Furthermore, there is an overall downward trend in the frequency of cold waves, with a declining frequency from 1961 to 2000, followed by a significant increase in frequency after 2000. Furthermore, the number of cold waves in the study area increased significantly after 2010.
Exploring ultralight sandwich structures with superior load-bearing performance is one of the important topics in structural optimization. This paper proposes a novel multiscale topology optimization ...method to achieve the design of high-performance sandwich structures with graded cellular cores (SSGCCs). In this method, the thicknesses of two solid face-sheets, the graded distribution of cellular sandwich cores at a single layer and their configurations are optimized to well suit for loading conditions, where the single layer is arrayed periodically at its height direction to obtain sandwich layers. Specifically, at macroscale, the variable thickness sheet (VTS) method with the capacity of generating an overall free material distribution pattern, is applied to optimize the thicknesses of two solid face-sheets and achieve the graded distribution of cellular sandwich cores at a single layer. At microscale, a progressive optimization scheme is employed to topologically optimize multiple representative cellular cores (RCCs) at a single layer, so as to achieve their similar topological configurations. With a shape interpolation method, the configurations of graded cellular cores (GCCs) with essential interconnections can be obtained by interpolating the shapes of these RCCs with similar topological features. In order to reduce the computational burden on evaluating effective properties of GCCs by the homogenization method, a Kriging metamodel is constructed based on some key cellular cores as sample points, and adopted to predict the effective properties of all the GCCs. Both 2D and 3D numerical examples are provided to test the validity and advantages of the proposed method for designing SSGCCs.
•A novel multiscale optimization for sandwich structures with graded cellular cores.•A progressive optimization scheme with a shape interpolation method is proposed.•Two face-sheet thicknesses and spatially-varying cellular cores are optimized.•Several 2D and 3D numerical examples are presented to validate the proposed method.
