Analysis on the Protection of Settlement Shape in Sichuan

This article elaborated the characteristics of settlement shape in detail with examples. Aiming at the negative effects on settlement shape by construction, we put forward some measures, such as respect for ecological environment, selection mode of space development, protection of historical features, and excavation of culture connotation, so as to realize the protection of settlement shape.

Nanochannels with a 18-nm feature size and ultrahigh aspect ratio on silica through surface assisting material ejection

.Nanochannel structures with a feature size deeply under the diffraction limit and a high aspect ratio hold huge biomedical significance,which is especially challenging to be realized on hard and brittle materials,such as silica,diamond,and sapphire.By simultaneously depositing the pulse energy on the surface and inside the sample,nanochannels with the smallest feature size of 18 nm(∼1∕30λ)and more than 200 aspect ratios are achieved inside silica,the mechanism of which can be concluded as the surface assisting material ejection effect.Both the experimental and theoretical results prove that the coaction of the superficial“hot domain”and internal hot domain dominates the generation of the nanochannels,which gives new insights into the laser-material interacting mechanisms and potentially promotes the corresponding application fields.

Spatial beam shaping by quartz crystal piano-convex lens

Based on the optical activity of quartz crystal, we proposed a scheme for shaping the spatial intensity distribution of a linearly polarized laser beam by utilizing a quartz crystal piano-convex lens in combination with a polarizer. The intensity profile of the shaped laser beam can be easily switched from one profile to another by controlling the polarization direction of the incident laser beam.

The Linac Coherent Light Source II photoinjector laser infrastructure

This paper presents a comprehensive technical overview of the Linac Coherent Light Source II(LCLS-II)photoinjector laser system,its first and foremost component.The LCLS-II photoinjector laser system serves as an upgrade to the original LCLS at SLAC National Accelerator Laboratory.This advanced laser system generates high-quality laser beams for the LCLS-II,contributing to the instrument's unprecedented brightness,precision and flexibility.Our discussion extends to the various subsystems that comprise the photoinjector,including the photocathode laser,laser heater and beam transport systems.Lastly,we draw attention to the ongoing research and development infrastructure underway to enhance the functionality and efficiency of the LCLS-II,and similar X-ray free-electron laser facilities around the world,thereby contributing to the future of laser technology and its applications.

Does City Shape Affect China's Economic Development?

This paper constructs a general equilibrium spatial urban model and measures city geometric compactness using the patch-shape index based on evidence from satellite imagery and basic vector maps of China.It adopts the ordinary least squares and instrumental variable approaches to examine the effect of city shape on the urban development of 279 Chinese cities at or above the prefecture level.The empirical results show that there was a significant negative correlation between city shape and economic outcomes.Specifically,every 1 percentage point increase in the patch-shape index led to a decrease in city-scale GDP by 0.009 percent,housing prices by 0.044 percent,and wages by 0.024 percent.More compact urban layouts attracted an inflow of households and firms,stimulated city economic growth,and were associated with increased housing prices and wage rates.The paper considers the cities'initial conditions,trends in population changes(expanding,shrinking,and stagnant cities),and geographic factors,and finds that the results are robust.An array of policy implications can be drawn from the research.

Progress of the injection laser system of SG-Ⅱ

A high power laser system was used to drive the ignition of inertial confinement fusion(ICF), of which the high energy,the uniform focal spot, the accurate laser waveform, and the synchronization between the laser beams are key parameters.To accomplish this, global laser characteristics control should be assured, which was the main purpose of the injection laser system. In this paper, the key technological progress involved in the improvement of the performance of the injection laser of SG-II is reported, including frequency domain control, time domain control, near-field spatial shaping, preamplifier technology, and the optical parametric chirped pulse amplification pump source.