Modulation of High-Order Harmonic Generation from a Monolayer ZnO by Co-rotating Two-Color Circularly Polarized Laser Fields

By numerically solving the two-dimensional semiconductor Bloch equation,we study the high-order harmonic emission of a monolayer ZnO under the driving of co-rotating two-color circularly polarized laser pulses.By changing the relative phase between the fundamental frequency field and the second one,it is found that the harmonic intensity in the platform region can be significantly modulated.In the higher order,the harmonic intensity can be increased by about one order of magnitude.Through time-frequency analysis,it is demonstrated that the emission trajectory of monolayer ZnO can be controlled by the relative phase,and the harmonic enhancement is caused by the second quantum trajectory with the higher emission probability.In addition,near-circularly polarized harmonics can be generated in the co-rotating two-color circularly polarized fields.With the change of the relative phase,the harmonics in the platform region can be altered from left-handed near-circularly polarization to right-handed one.Our results can obtain high-intensity harmonic radiation with an adjustable ellipticity,which provides an opportunity for syntheses of circularly polarized attosecond pulses.

ESTIMATE ON THE BLOCH CONSTANT FOR CERTAIN HARMONIC MAPPINGS UNDER A DIFFERENTIAL OPERATOR

In this paper,we first obtain the precise values of the univalent radius and the Bloch constant for harmonic mappings of the formL(f)=zfz-zfz,where f represents normalized harmonic mappings with bounded dilation.Then,using these results,we present better estimations for the Bloch constants of certain harmonic mappings L(f),where f is a K-quasiregular harmonic or open harmonic.Finally,we establish three versions of BlochLandau type theorem for biharmonic mappings of the form L(f).These results are sharp in some given cases and improve the related results of earlier authors.

学校社会工作在日本中小学实践中的发展路径及启示

日本在义务教育发展的百年历程中,逐渐意识到仅依靠传统的教育方式并不能有效应对学校内部的问题与需求。特别是在全球化发展之后,学生的教育需求趋于复杂化与多元化,为此,日本政府结合学生的实际情况,要求以学校为主导在校内开展学校社会工作。学校社会工作不仅要配合学校建立服务团队,还要与校外相关部门和机构建立合作关系网络。本文通过分析日本学校社会工作创建的成因,解释了其在辅助教育政策实施过程中的功能及其发挥机制,深入探讨了日本学校社会工作对维护儿童权利的实践路径,并从中获得启示。

Harmonics in the Squirrel Cage Induction Motor Analytic Calculation Part III: Influence on the Torque-speed Characteristic

The harmonics that appear in the squirrel cage asynchronous machine have been discussed in great detail in the literature for a long time. However, the systematization of the phenomenon is still pending, so we made an attempt to fill this gap in the previous parts of our study by elaborating formulas for calculation of parasitic torques. It was a general demand among those who work in this field towards the author to verify his formulas with measurements. In the literature, it seems,only one detailed, purposeful series of measurements has been published so far, the purpose of which was to investigate the effect of the number of rotor slots on the torque-speed characteristic curve of the machine. The main goal of this study is to verify the correctness of the formulas by comparing them with the referred series of measurements. Relying on this, the expected synchronous parasitic torques were developed for the frequently used rotor slot numbers-as a design guide for the engineer.Thus, together with our complete table for radial magnetic pull published in our previous work, the designer has all the principles, data and formulas available for the right number of rotor slots for his given machine and for the drive system. This brings this series of papers to an end.

《孔子家语》在古代日本的传播与接受考论

《孔子家语》在九世纪由我国传入日本,呈现出独特的传播路径与接受方式。史料证实,在平安时代,《孔子家语》被藤原家族私藏,后被收录至《群书治要》,当时的天皇也曾诵读。通过考察平安时代《本朝文粹》的流传和接受状况,进一步证实了《孔子家语》在平安时代一直处于被限制传播的状态。在镰仓至室町时代,由于战乱频发,《孔子家语》才开始在民间流传,且呈现出多样化的接受形态。在江户时代初期的文教政策下,《孔子家语》受到德川家康的推崇,从而促进了其在普通民众间的广泛传播。

世界大变局下日本供应链安全政策调整及对中国的启示

在新冠疫情影响深重、中美战略竞争激化、乌克兰危机深化、巴以冲突升级的背景下,全球供应链正经历着百年未有之大变局。日本作为世界第三大经济体,针对本国供应链的脆弱,多次召开“经济安全保障会议”制定供应链保护政策,使得供应链布局发生了从“追求效率最优”向增强“供应链韧性和可持续性”的转变。与此同时,日本还强化了与以美国为首的盟国在经济安全问题上的合作。日本的供应链政策调整,使得中国可能面临高技术领域技术空缺、日企对华投资减少、中日供应链“脱钩”等风险。中国企业应在增强透明度、提升人才培养能力和创新水平以及加强与其他国家、国际组织合作等方面,继续探索本国经济安全保障的可行路径。中日两国只有加强合作与交流,共同应对供应链安全等问题,才能维护全球供应链的稳定和促进共同发展。

日本医籍《痘科键私衡》学术内容与特色

《痘科键私衡》是一部由日本医家池田瑞英所著的对《痘科键》一书进行评注与释义的中医痘科专著。书中选录了《痘科键》原文149条,主要围绕痘症的病因病机、兼变症、治法治方、预后转归等方面对每一条原文进行精深地评释。全书共6卷,包括卷一《痘科键私衡·总论之上》、卷二《痘科键私衡·总论之中》、卷三《痘科键私衡·总论之下》、卷四《痘科键私衡·诀程之上》、卷五《痘科键私衡·诀程之中》、卷六《痘科键私衡·诀程之下》。总论主要阐述了痘症的类别、症状、形状、神采、证候、兼变症及其病因病机、治法治方、预后转归等内容;诀程主要论述了痘症中的发热、出点、起胀、灌脓、收靥、落痂的症状、兼变症、病症鉴别、病势及其发病机制、辨证论治、分期施治、药物加减及预后转归等内容。《痘科键私衡》体例严谨,井然有序;书页完整,装帧精美;注释经典,旁征博引;内容精详,面面俱圆;一脉相承,不拘于书。其是《痘科键》的继承与发展,丰富与深化了痘科的理论体系,对痘科的文献与临床研究具有重要意义。

日本“儿童食堂”项目及其对中国的启示

儿童营养的改善,既关系到科教兴国战略的推进,又关系到民生福祉的增进,是实现中国式现代化的重要内容和关键环节。中国《营养改善计划》实施已十年有余,取得了显著成绩,但也存在一定的问题,需要进一步完善。通过改善儿童膳食保障青少年的健康成长,是世界各国尤其是发达国家的普遍做法。日本“儿童食堂”项目对于完善我国《营养改善计划》具有重要借鉴意义。通过对日本“儿童食堂”项目的产生背景、发展历程和运营模式进行梳理可以看出,日本“儿童食堂”项目中既有值得我们借鉴的成功经验,也有需要完善和改进的不足之处。日本“儿童食堂”项目启示我们,完善中国的《营养改善计划》,应当充分发挥法治的重要作用和媒体应有的作用,进一步加强实地监督和饮食教育。

枯山水艺术在日本园林景观设计中的应用

枯山水是日本传统园林的一种艺术形式,通过自然元素的简约布置,体现了禅宗的哲学思想和对美的追求。探讨了枯山水的历史发展、审美价值,分析了枯山水艺术在空间布局、材料选择、造型设计等方面的应用特点和创新手法,并对比了传统与现代枯山水的不同表现。通过运用枯山水艺术,能创造出富有诗意和禅意的空间氛围,使人们能在其中感受到自然与人文的和谐共生。

也谈中国、日本士大夫与朝鲜朝使臣交友中的“情”与“泪”--兼与夫马进教授商榷

日本学者夫马进教授以朝鲜朝通信史元重举与燕行使洪大容为例,探讨清代中、日、朝鲜三国士人不同的“情”世界,认为朝鲜朝使者在日本与中国都与当地的文人保持着深厚的情谊,注意到中、日两国人为情流泪的情况,而朝鲜朝文人很少流泪,并认为朝鲜朝使臣这种极力抑制的精神来自“朱子学的精神”等。通过对当时中、朝、日人士交往的考察可以看出,中国士人自古以来即有“生离死别”与“黯然销魂”的感情,他们在为朝鲜朝朋友送行时的泪眼,都是对这种离别文化下发自内心的自然反应;燕行使所交往的中国士人多为南方人,他们在心底隐藏着“双重的离别”,极易引起感情的强烈共鸣,以至“掩泣汍澜”;燕行使臣所感知到的中国士人“稍过”的离别泪眼,既是真诚的,也颇具表演性;朝鲜朝文人也具有丰富的感情,也经常泪眼濛濛,但很少当众流泪;朝鲜朝通信使在日本有着种族与文化的优越感,不屑于同日本人谈艺论学,只是机械、漠然地应付各种接待仪式。三国人士之流泪与否,与“朱子学的精神”等没有直接的关联。

H_(3)Se in the Imˉ3m Phase:High-Pressure Superconductor with T_(c) Reaching 200K at 64GPa Mediated by Anharmonic Phonons

Hydrogen-based compounds have attracted significant attention in recent years due to the discovery of conventional superconductivity with high critical temperature under high pressure,rekindling hopes for finding roomtemperature superconductors.In this study,we investigated the vibrational and superconducting properties of H_(3)Sein the Im￣3m phase under pressures of 50-200GPa.Our approach combines the stochastic self-consistent harmonic approximation and first-principles calculations to account for the quantum and anharmonic effects of ions.According to the results,these effects significantly modify the crystal structure,increasing the inner pressure by approximately 8GPa compared to situations in which they are ignored.The phonon spectra suggest that when these effects are considered,the crystal stabilizes at pressures as low as approximately 61GPa,which is significantly lower than the previously predicted value of over 100GPa.Our calculations also highlight the critical role of quantum and anharmonic effects on the electron-phonon coupling properties.Neglecting these factors can result in a significant overestimation of the superconducting critical temperature(T_(c))by approximately 4K(200GPa)to 25K(125GPa).With anharmonic phonons,the T_(c) calculated from the Migdal-Eliashberg equations reaches 200K(μ⋆=0.1,λ=4.1)as the pressure decreases to 64GPa,indicating that the crystal is a rare high-Tc superconductor at moderate pressures.

Bunching enhancement for coherent harmonic generation by using phase merging effects

In this paper,promising but simple schemes are investigated to enhance the micro-bunching of relativistic electron beams for coherent harmonic generation(CHG)by using phase merging effects.In contrast to the standard CHG scheme,two specially designed dispersion sections(DSs)are adopted with the DS-modulator–DS configuration.The phase space of the e beam is appropriately coupled in the first DS,and the electrons within one seed wavelength can merge to the same phase with a matched second DS.Micro-bunching of the e beam can thus be enhanced by a large margin with much higher-harmonic components.Taking e beams from laser wakefield accelerators(LWFAs)as an example,start-to-end simulations are performed to show the effectiveness and robustness of the proposed schemes with several configurations.The beam current can be optimized to several tens to hundreds of kiloamperes,and the radiation power reaches hundreds of megawatts in the extreme ultraviolet regime within a 3.5 m-long beamline.The proposed schemes offer new opportunities for future compact free-electron lasers driven by LWFAs and provides prospects for truly compact and widely applicable systems.

High-order harmonic generation of ZnO crystals in chirped and static electric fields

High harmonic generation in ZnO crystals under chirped single-color field and static electric field are investigated by solving the semiconductor Bloch equation(SBE). It is found that when the chirp pulse is introduced, the interference structure becomes obvious while the harmonic cutoff is not extended. Furthermore, the harmonic efficiency is improved when the static electric field is included. These phenomena are demonstrated by the classical recollision model in real space affected by the waveform of laser field and inversion symmetry. Specifically, the electron motion in k-space shows that the change of waveform and the destruction of the symmetry of the laser field lead to the incomplete X-structure of the crystal-momentum-resolved(k-resolved) inter-band harmonic spectrum. Furthermore, a pre-acceleration process in the solid four-step model is confirmed.

Tunable spectral continuous shift of high-order harmonic generation in atoms by a plasmon-assisted shaping pulse

We delve into the phenomenon of high-order harmonic generation within a helium atom under the influence of a plasmon-assisted shaping pulse.Our findings reveal an intriguing manipulation of the frequency peak position in the harmonic emission by adjusting the absolute phase parameter within the frequency domain of the shaping pulse.This phenomenon holds potential significance for experimental setups necessitating precisely tuned single harmonics.Notably,we observe a modulated shift in the created harmonic photon energy,spanning an impressive range of 1.2 eV.This frequency peak shift is rooted in the asymmetry exhibited by the rising and falling edges of the laser pulse,directly influencing the position of the peak frequency emission.Our study quantifies the dependence of this tuning range and the asymmetry of the laser pulse,offering valuable insights into the underlying mechanisms driving this phenomenon.Furthermore,our investigation uncovers the emergence of semi-integer order harmonics as the phase parameter is altered.We attribute this discovery to the intricate interference between harmonics generated by the primary and secondary return cores.This observation introduces an innovative approach for generating semi-integer order harmonics,thus expanding our understanding of high-order harmonic generation.Ultimately,our work contributes to the broader comprehension of complex phenomena in laser-matter interactions and provides a foundation for harnessing these effects in various applications,particularly those involving precise spectral control and the generation of unique harmonic patterns.

Electron correlation in two-electron atoms:A Bohmian analysis of high-order harmonic generation in high-frequency domain

In studying interactions between intense laser fields and atoms or molecules,the role of electron correlation effects on the dynamical response is an important and pressing issue to address.Utilizing Bohmian mechanics(BM),we have theoretically explored the two-electron correlation characteristics while generating high-order harmonics in xenon atoms subjected to intense laser fields.We initially employed Bohmian trajectories to reproduce the dynamics of the electrons and subsequently utilized time-frequency analysis spectra to ascertain the emission time windows for high-order harmonics.Within these time windows,we classified the nuclear region Bohmian trajectories and observed that intense high-order harmonics are solely generated when paired Bohmian particles(BPs)concurrently appear in the nuclear region and reside there for a duration within a re-collision time window.Furthermore,our analysis of characteristic trajectories producing high-order harmonics led us to propose a two-electron re-collision model to elucidate this phenomenon.The study demonstrates that intense high-order harmonics are only generated when both electrons are in the ground state within the re-collision time window.This work discusses the implications of correlation effects between two electrons and offers valuable insights for studying correlation in multi-electron high-order harmonic generation.

ON THE UNIVALENCE OF CERTAIN POLYHARMONIC MAPPINGS WITH BOUNDED LENGTH DISTORTIONS

The main purpose of this paper is to investigate the univalence of normalized polyharmonic mappings with bounded length distortions in the unit disk.We first establish the coefficient estimates for polyharmonic mappings with bounded length distortions.Then,using these results,we establish five Landau-type theorems for subclasses of polyharmonic mappings F and L(F),where F has bounded length distortion and L is a differential operator.

VALUE DISTRIBUTION PROPERTIES FOR GAUSS MAPS OF IMMERSED HARMONIC SURFACES RAMIFIED OVER HYPERSURFACES

In this paper,we study the value distribution properties of the generalized Gauss maps of weakly complete harmonic surfaces immersed in R^(m),which is the case where the generalized Gauss mapΦis ramified over a family of hypersurfaces{Q_(j)}_(j=1)^(q)in P^(m-1)(C)located in the N-subgeneral position.In addition,we investigate the Gauss curvature estimate for the K-quasiconformal harmonic surfaces immersed in R^(3)whose Gauss maps are ramified over a family of hypersurfaces located in the N-subgeneral position.

Abnormal transition of the electron energy distribution with excitation of the second harmonic in low-pressure radio-frequency capacitively coupled plasmas

The self-excited second harmonic in radio-frequency capacitively coupled plasma was significantly enhanced by adjusting the external variable capacitor.At a lower pressure of 3 Pa,the excitation of the second harmonic caused an abnormal transition of the electron energy probability function,resulting in abrupt changes in the electron density and temperature.Such changes in the electron energy probability function as well as the electron density and temperature were not observed at the higher pressure of 16 Pa under similar harmonic changes.The phenomena are related to the influence of the second harmonic on stochastic heating,which is determined by both amplitude and the relative phase of the harmonics.The results suggest that the self-excited high-order harmonics must be considered in practical applications of lowpressure radio-frequency capacitively coupled plasmas.

Terahertz quasi-perfect vortex beam with integer-order and fractional-order generated by spiral spherical harmonic axicon

We propose a new method to generate terahertz perfect vortex beam with integer-order and fractional-order. A new optical diffractive element composed of the phase combination of a spherical harmonic axicon and a spiral phase plate is designed and called spiral spherical harmonic axicon. A terahertz Gaussian beam passes through the spiral spherical harmonic axicon to generate a terahertz vortex beam. When only the topological charge number carried by spiral spherical harmonic axicon increases, the ring radius of terahertz vortex beam increases slightly, so the beam is shaped into a terahertz quasi-perfect vortex beam. Importantly, the terahertz quasi-perfect vortex beam can carry not only integer-order topological charge number but also fractional-order topological charge number. This is the first time that vortex beam and quasi-perfect vortex beam with fractional-order have been successfully realized in terahertz domain and experiment.

THE GRADIENT ESTIMATE OF SUBELLIPTIC HARMONIC MAPS WITH A POTENTIAL

In this paper,we investigate subelliptic harmonic maps with a potential from noncompact complete sub-Riemannian manifolds corresponding to totally geodesic Riemannian foliations.Under some suitable conditions,we give the gradient estimates of these maps and establish a Liouville type result.