Time-resolved Measurement of Quadrupole Wakefields in Corrugated Structures

Corrugated structures have recently been widely used for manipulating electron beam longitudinal phase space and for producing THz radiation. Here we report on time-resolved measurements of the quadrupole wakefields in planar corrugated structures. It is shown that while the time- dependent quadrupole wakefield produced by a planar corrugated structure causes significant growth in beam transverse emittance, it can be effectively canceled with a second corrugated structure with orthogonal orientation. The strengths of the time-dependent quadrupole wakefields for various corrugated structure gaps are also measured and found to be in good agreement with theories. Our work should forward the applications of corrugated structures in many accelerator based scientific facilities

Few-femtosecond Electron Beam with THz-frequency Wakefield-driven Compression

We propose and demonstrate a novel method to produce few-femtosecond electron beam with relatively low timing jitter. In this method a relativistic electron beam is compressed from about 150 fs (rms) to about 7 fs (rms, upper limit) with the wakefield at THz frequency produced by a leading drive beam in a dielectric tube. By imprinting the energy chirp in a passive way, we demonstrate through laser-driven THz streaking technique that no additional timing jitter with respect to an external laser is introduced in this bunch compression process, a prominent advantage over the conventional method using radio-frequency bunchers. We expect that this passive bunching technique may enable new opportunities in many ultrashort-beam based advanced applications such as ultrafast electron diffraction and plasma wakefield acceleration.Comment: 5 pages, 4 figure

An intelligent network control system for plug-in electric vehicles and the associate communication mechanism

The development of an intelligent plug-in electric vehicle (PEV) network is an important research topic in the smart grid environment. An intelligent PEV network enables a flexible control of PEV charging and discharging activities and hence PEVs can be utilized as ancillary service providers in the power system concerned. Given this background, an intelligent PEV network architecture is first developed, and followed by detailed designs of its application layers, including the charging and discharging controlling system, mobility and roaming management, as well as communication mechanisms associated. The presented architecture leverages the philosophy in mobile communication network buildu

Uneven wear behavior of downhole tool clearance material under slurry erosion

Slurry erosion of clearance fits is one of the primary reasons for the decline in the performance of downhole tools. In this study, slurry erosion experiments and computational fluid dynamics simulations were performed to understand the effect of particle impact velocity as well as the erosion mechanisms on the surface of 38CrMoAlA steel. The results indicated that uneven erosive wear occurred along the flow direction on the surface of clearance material. The uneven erosive wear can be attributed to the variation of particle impact angle affected by fluid streamlines. The site and the area of the most severe erosion changed arising from the particle impact velocity. The failure of the clearance material was mainly due to the aggravation of localized erosion wear. To extend the service life of downhole tools, the region downstream of the clearance inlet (10 mm from the inlet) should be prioritized

Cross-Scale Interaction With Spatial-Spectral Enhanced Window Attention for Pansharpening

Pansharpening is a process that fuses a multispectral (MS) image with a panchromatic (PAN) image to generate a high-resolution multispectral (HRMS) image. Current methods often overlook scale inconsistency and the correlation within and between a window domain, resulting in suboptimal outcomes. In addition, the use of deep convolutional neural network or transformer often leads to high computational expenses. To address these challenges, we present a lightweight pansharpening network that leverages cross-scale interaction and spatial-spectral enhanced window attention. We first design a spatial-spectral enhanced window transformer (SEWformer) to effectively capture crucial attention within and between interleaved windows. To improve scale consistency, we develop a cross-scale interactive encoder that interacts with different scale attentions derived from the SEWformer. Furthermore, a multiscale residual network with channel attention is constructed as a decoder, which, in conjunction with the encoder, ensures precise detail extraction. The final HRMS image is obtained by combining the extracted details with the UPMS image. Extensive experimental validation on diverse datasets showcases the superiority of our approach over state-of-the-art pansharpening techniques in terms of both performance and efficiency. Compared to the second-best comparison approach, our method achieves significant improvements in the ERGAS metric: 29.6$\%$ on IKONOS, 43.8$\%$ on Pléiades, and 27.6$\%$ on WorldView-3 datasets