Intense Mid-Infrared Laser Pulse Generated via Flying-Mirror Red-Shifting in Near-Critical-Density Plasmas

Relativistic femtosecond mid-infrared pulses can be generated efficiently by laser interaction with near-criticaldensity plasmas.It is found theoretically and numerically that the radiation pressure of a circularly polarized laser pulse first compresses the plasma electrons to form a dense flying mirror with a relativistic high speed.The pulse reflected by the mirror is red-shifted to the mid-infrared range.Full three-dimensional simulations demonstrate that the central wavelength of the mid-infrared pulse is tunable from 3µm to 14µm,and the laser energy conversion efficiency can reach as high as 13%.With a 0.5–10 PW incident laser pulse,the generated mid-infrared pulse reaches a peak power of 10–180 TW,which is interesting for various applications in ultrafast and high-field sciences.

Improved mass relations of mirror nuclei

In this study,we revisit the previous mass relations of mirror nuclei by considering 1/N-and 1/Z-dependent terms and the shell effect across a shell.The root-mean-squared deviation is 66 keV for 116 nuclei with neutron number N≥10,as com-pared with experimental data compiled in the AME2020 database.The predicted mass excesses of 173 proton-rich nuclei,including 98 unknown nuclei,are tabulated in the Supplemental Material herein with competitive accuracy.

Fuzzy Proportional Integral Derivative control of a voice coil actuator system for adaptive deformable mirrors

Research on adaptive deformable mirror technology for voice coil actuators(VCAs)is an important trend in the development of large ground-based telescopes.A voice coil adaptive deformable mirror contains a large number of actuators,and there are problems with structural coupling and large temperature increases in their internal coils.Additionally,parameters of the traditional proportional integral derivative(PID)control cannot be adjusted in real-time to adapt to system changes.These problems can be addressed by introducing fuzzy control methods.A table lookup method is adopted to replace real-time calculations of the regular fuzzy controller during the control process,and a prototype platform has been established to verify the effectiveness and robustness of this process.Experimental tests compare the control performance of traditional and fuzzy proportional integral derivative(Fuzzy-PID)controllers,showing that,in system step response tests,the fuzzy control system reduces rise time by 20.25%,decreases overshoot by 78.24%,and shortens settling time by 67.59%.In disturbance rejection experiments,fuzzy control achieves a 46.09%reduction in the maximum deviation,indicating stronger robustness.The Fuzzy-PID controller,based on table lookup,outperforms the standard controller significantly,showing excellent potential for enhancing the dynamic performance and disturbance rejection capability of the voice coil motor actuator system.

An electromagnetic semi-active dynamic vibration absorber for thin-walled workpiece vibration suppression in mirror milling

As critical components of aircraft skins and rocket fuel storage tank shells,large thin-walled workpieces are susceptible to vibration and deformation during machining due to their weak local stiffness.To address these challenges,we propose a novel tunable electromagnetic semi-active dynamic vibration absorber(ESADVA),which integrates with a magnetic suction follower to form a followed ESADVA(follow-ESADVA)for mirror milling.This system combines a tunable magnet oscillator with a follower,enabling real-time vibration absorption and condition feedback throughout the milling process.Additionally,the device supports self-sensing and frequency adjustment by providing feedback to a linear actuator,which alters the distance between magnets.This resolves the traditional issue of being unable to directly monitor vibration at the machining point due to space constraints and tool interference.The frequency shift characteristics and vibration absorption performance are comprehensively investigated.Theoretical and experimental results demonstrate that the prototyped follow-ESADVA achieves frequency synchronization with the milling tool,resulting in a vibration suppression rate of approximately 47.57%.Moreover,the roughness of the machined surface decreases by18.95%,significantly enhancing the surface quality.The results of this work pave the way for higher-quality machined surfaces and a more stable mirror milling process.

Mirror Stage Theory Analysis of Bravery in Zootopia(2016)and Nezha(2019)

American Hollywood animated films have conquered the world.In recent years,many successful works have appeared in domestic animated films,bringing new vitality to the Chinese animated film industry.Based on Lacan’s Mirror Stage Theory,this study attempts to start from the bravery of Judy and Nezha,the protagonists of Zootopia(2016)and Nezha(2019).It analyzes and compares their embodiment,formation,influence and reflection with real society to solve the problems of the two brave characters’formation causes,characteristic differences and social influences,including racial discrimination,individualism in American society and family problems in Chinese society.This study sheds light on the transmission of intercultural values in animated films.

Constraining nuclear symmetry energy with the charge radii of mirror-pair nuclei

The nuclear charge radius plays a vital role in determining the equation of state of isospin asymmetric nuclear matter.Based on the correlation between the differences in charge radii of mirror-partner nuclei and the slope parameter(L)of symmetry energy at the nuclear saturation density,an analysis of the calibrated slope parameter L was performed in finite nuclei.In this study,relativistic and nonrelativistic energy density functionals were employed to constrain the nuclear symmetry energy through the available databases of the mirror-pair nuclei^(36)Ca–^(36)S,^(38)Ca–^(38)Ar,and ^(54)Ni–^(54)Fe.The deduced nuclear symmetry energy was located in the range 29.89–31.85 MeV,and L of the symmetry energy essentially covered the range 22.50–51.55 MeV at the saturation density.Moreover,the extracted L_(s) at the sensitivity density p_(s)=0.10 fm^(-3) was located in the interval range 30.52–39.76 MeV.

High-resolution visible imaging with piezoelectric deformable secondary mirror: experimental results at the 1.8-m adaptive telescope

Integrating deformable mirrors within the optical train of an adaptive telescope was one of the major innovations in astronomical observation technology,distinguished by its high optical throughput,reduced optical surfaces,and the incorporation of the deformable mirror.Typically,voice-coil actuators are used,which require additional position sensors,internal control electronics,and cooling systems,leading to a very complex structure.Piezoelectric deformable secondary mirror technologies were proposed to overcome these problems.Recently,a high-order piezoelectric deformable secondary mirror has been developed and installed on the 1.8-m telescope at Lijiang Observatory in China to make it an adaptive telescope.The system consists of a 241-actuator piezoelectric deformable secondary mirror,a 192-sub-aperture Shack-Hartmann wavefront sensor,and a multi-core-based real-time controller.The actuator spacing of the PDSM measures 19.3 mm,equivalent to approximately 12.6 cm when mapped onto the primary mirror,significantly less than the voicecoil-based adaptive telescopes such as LBT,Magellan and VLT.As a result,stellar images with Strehl ratios above 0.49 in the R band have been obtained.To our knowledge,these are the highest R band images captured by an adaptive telescope with deformable secondary mirrors.Here,we report the system description and on-sky performance of this adaptive telescope.

Two types of mirror mode waves in the Kronian magnetosheath

A mirror mode wave is a fundamental magnetic structure in the planetary space environment that is persistently compressed by solar wind,especially in the magnetosheath.Mirror modes have been widely identified in the magnetosheaths of the Earth and other planets in the solar system,yet the understanding of mirror mode waves on extraterrestrial planets is not as comprehensive as that on the Earth.Using magnetic field data collected by the Cassini spacecraft,we found peak and dip types according to the magnetic morphology(i.e.,structures with higher or lower magnetic strengths than the background field).Moreover,mirror mode waves and electromagnetic ion cyclotron waves were found one after the other,implying that the two wave modes may evolve into one another in the Kronian magnetosheath.The results indicate that many fundamental plasma processes associated with the mirror mode structure exist in the Kronian magnetosheath.The energy conversion in Saturn’s magnetosheath may provide key insights that will aid in understanding giant planetary magnetospheric processes.

Is a mirror necessary for mirror therapy?

Since it was first described as a method to treat phantom limb pain, mirror therapy(MT) has been applied in many areas of rehabilitation. Its seminal application with the aim of restoring motor function following stroke is considered to be that of Altschuler et al.(1999).

Effects of Different Feedback Conditions on Sensorimotor Adaptation Revealed in a Mirror Reversal Paradigm

Humans are able to overcome sensory perturbations imposed on their movements through motor learning. One of the key mechanisms to accomplish this is sensorimotor adaptation, an implicit, error-driven learning mechanism. Past work on sensorimotor adaptation focused mainly on adaptation to rotated visual feedback—A paradigm known as visuomotor rotation. Recent studies have shown that sensorimotor adaptation can also occur under mirror-reversed visual feedback. In visuomotor rotation, sensorimotor adaptation can be driven by both endpoint and online feedback [1] [2]. However, it’s not been clear whether both kinds of feedback can similarly drive adaptation under a mirror reversed perturbation. We performed a study to establish what kinds of feedback can drive adaptation under mirror reversal. In the first two conditions, the participants were asked to ignore visual feedback. In the first condition, we provided mirror reversed online feedback and endpoint feedback. We reproduced previous findings showing that online feedback elicited adaptation under mirror reversal. In a second condition, we provided mirror reversed endpoint feedback. However, in the second condition, we found that endpoint feedback alone failed to elicit adaptation. In a third condition, we provided both types of feedback at the same time, but in a conflicting way: endpoint feedback was non-reversed while online feedback was mirror reversed. The participants were asked to ignore online visual feedback and try to hit the target with help from veridical endpoint feedback. In the third condition, in which veridical endpoint feedback and mirror reversed online feedback were provided, adaptation still occurred. Our results showed that endpoint feedback did not elicit adaptation under mirror reversal but online feedback did. This dissociation between effects of endpoint feedback and online feedback on adaptation under mirror reversal suggests that adaptation under these different kinds of feedback might in fact operate via distinct mechanisms.

Experimental studies of cusp stabilization in Keda Mirror with AXisymmetricity(KMAX)

Stabilization of the axisymmetric magnetic mirror relies on the pressure-weighted magnetic field curvature.We report a new experiment by configuring a magnetic cusp structure to stabilize m=1 interchange mode in the KMAX tandem mirror.The cusp configuration is formed by reversing currents in the two side cell coils,and a stronger cusp can lead to a more stable plasma once the null point of the cusp is less than 35–40 cm away from the device axis.The density fluctuations measured by four axial Langmuir probes are mitigated by 70%–80%.The stabilization effect is consistent with the prediction of a theoretical calculation.

STABILITY CONDITIONS AND THE MIRROR SYMMETRY OF K3 SURFACES IN ATTRACTOR BACKGROUNDS

We study the space of stability conditions on K3 surfaces from the perspective of mirror symmetry. This is done in the attractor backgrounds(moduli). We find certain highly non-generic behaviors of marginal stability walls(a key notion in the study of wall crossings)in the space of stability conditions. These correspond via mirror symmetry to some nongeneric behaviors of special Lagrangians in an attractor background. The main results can be understood as a mirror correspondence in a synthesis of the homological mirror conjecture and SYZ mirror conjecture.

Development of aperiodic multilayer mirrors operated at W-Lβline for plasma diagnostics application

Multilayer interference mirrors play a pivotal role in spectroscopic diagnostic systems,which probe electron temperature and density during inertial confinement fusion processes.In this study,aperiodic Mo/B_(4)C multilayer mirrors of varied thick-nesses were investigated for X-ray plasma diagnostics at the 9.67-keV W-Lβline.The thickness distribution of the aperiodic multilayers was designed using the first Bragg diffraction condition and then optimized through a simplex algorithm to realize a narrow bandwidth and consistent spectral response.To enhance spectral accuracy,further refinements were undertaken by matching the grazing incidence X-ray reflectivity data with actual structural parameters.X-ray reflectivity measurements from the SSRF synchrotron radiation facility on the optimized sample showed a reflectivity of 29.7±2.6%,flat-band range of 1.3 keV,and bandwidth of 1.7 keV,making it suitable for high-temperature plasma diagnostics.The study explored the potential of predicting the 9.67 keV reflectivity spectrum using the fitting data from the grazing incidence X-ray reflectivity curves at 8.05 keV.Additionally,the short-term thermal stability of an aperiodic multilayer was assessed using temperature-dependent in situ X-ray measurements.Shifts in the reflectivity spectrum during annealing were attributed to interdiffusion and interfacial relaxation.The research team recommends the aperiodic Mo/B_(4)C multilayer mirror for operations below 300℃.

Eight Reasons to Consider History as a Mirror

Understanding the China-U.S. relations from a historical perspective.WHEN President Xi Jinping met his U.S. counterpart Joe Biden on the sidelines of the G20 Summit in Bali in November, 2022, he said, "History is the best textbook. We should take it as a mirror and let it guide the future."

Mirroring Two Anicent Civilizations

In the eyes of Croatian archaeologist Goran Durdevic,an ancient mirror can also reflect cultural exchanges along the ancient Silk Road.GORAN Durdevic,aged 35,is an archaeolo-gist from Croatia.Since 2013,following the launch of the Belt and Road Initiative(BRI),there has been increasing cooperation between Chinese universities and those in B&R member countries.is entailed some Chinese universities expanding enrollment to include international students from those countries.In 2017,Goran,who was in Croatia at the time,saw the news of the enrollment and applied to study at the School of History at Capital Normal University in Beijing,China.During his six-year stay in China,he carried out comparative research on bronze mirrors from the Chinese Han Dynasty(206 BC-AD 220)and ancient Rome.When it comes to the Chinese and Western allusions pertaining to mirrors,Goran can name a list of ancient Chinese philosophies which are inspiring to him.“In the Tang Dynasty(618-907),people believed that by using copper as a mirror,one could check one’s physical appearance;by using people as a mirror,one could understand gains and losses;and by using history as a mirror,one could know the rise and fall of regimes.”

Web 3.0时代的内容出版平台——Mirror个案研究

随着技术和社会的发展,内容产业面临许多Web2.0无法解决的问题。Web3.0以其去中心化、重视用户价值、强调用户所有权与控制权的特点,为数字出版产业提供了全新发展机遇,与之相关的区块链技术、基于区块链技术的NFT也在内容市场中大放异彩。本文以去中心化的内容出版平台Mirror为例,分析如何从去中心化的内容出版、NFT所有权经济模式和自治开放的社区三个方面入手解决当前的出版难题,从而增进对Web3.0时代出版平台功能与形态的认知。

Design and Research of Active Gravity Unloading Device for Large Aperture Optical Mirror

The large aperture optical mirror for space is processed and tested in the gravity environment on the ground. After entering space, gravity disappears due to the change of environment, and the mirror surface that has met the engineering requirements on the ground will change, seriously affecting the imaging quality. In order to eliminate the influence of gravity and to ensure the consistency of space and ground, gravity unloading must be performed. In order to meet the requirements of processing and testing for the large aperture space mirror in the state of vertical optical axis, a universal gravity unloading device was proposed. It was an active support and used air cylinders to provide accurate unloading force. First, the design flow of gravity unloading was introduced;then the detailed design of the mechanical structure and control system was given;then the performance parameters of the two types of cylinders were tested and compared, including the force-pressure relationship curve and the force-position relationship curve;finally, the experimental verification of the gravity unloading device was carried out;for a mirror with an aperture of ?2100 mm, the gravity unloading device was designed and a vertical detection optical path was built. The test results showed that by using this gravity unloading device, the actual processing surface accuracy of the mirror was better than 1/50λ-RMS, which met the application requirement of the optical system. Thus, it can be seen that using this gravity unloading device can effectively unload the gravity of the mirror and realize the accurate processing and measurement of the mirror surface. .

媒介变革中网络文学现实观照的幻像强化——从Internet到Sora的技术迁跃

网络文学的媒介提供了一种虚拟空间的文化交流与精神对话方式。伴随着互联网媒介生产技术从早期诞生到Sora AI问世的持续发展,文艺同社会生活边界的日渐模糊,进而打破了以往同社会存在遥远距离的束缚,以一种超现实的虚拟空间状态进入社会大众的生活。网络文艺创作将个体“无意识之思”通过超现实的叙事表达在集体“无意识之思”的公共语境空间内,并通过一种“在场”式体验的创作同创作者与阅读者构成共同的语意空间。而由于公共语境空间的平等交流性,读者与创作者都在他者介入的影响下参与到网络文艺在“自我理想”中找寻“理想自我”的过程中。

大口径环形分段光学系统基准构建方法

为了更好地对大口径分段望远镜进行集成检测与稳定性保持基准构建,本文提出一种大口径环形分段光学系统基准构建方法。首先,采用局部光瞳投射的方式实现光瞳对准映射;其次,利用微透镜阵列构建系统共焦空间基准;之后,基于环带整体调控模式,采用共焦与曲率半径联合分析,实现曲率半径与系统对准的共同调节;最后,利用白光干涉所形成的条纹包络进行粗共相探测,并利用通道光谱方法实现粗共相与精共相间的精度衔接,空间共焦基准定位精度优于125μm,共相基准覆盖范围优于20μm,精度优于0.5μm,光谱基准不确定度优于5%。实现了不同时空特征扰动的分层次、多模态抑制,利用以上共基准原位测量新方法有效提升了光学系统原位计量检测精度并缩短了溯源链长度,增加了检测效率与准确度。

太阳成像仪镜筒舱内压力控制技术研究

文章阐述了太阳成像仪镜筒舱内压力控制技术研究,主要包括限流小孔机械尺寸理论分析、慢速泄压阀设计、镜筒压力控制模拟测试等内容。目前,所研制的慢速泄压阀已顺利交付使用,并随46.5 nm极紫外太阳成像仪在中科院空间新技术试验卫星上进行了搭载,实现了在轨顺利开机,验证了太阳成像仪镜筒舱内压力控制手段的正确性。