Research on wavefront error of prism induced by thermoelastic distortion

To meet the design and usage requirements of the precision light beam scanner, the thermoelastic distortion of prism is detailedly analyzed by the thermal-structure coupling method, the influence of which, on the surface deformations of prism, is conclusively proved far greater than that of only the gravity load without temperature fluctuation. With the temperature fluctuation from 20 to 20.5 ℃, the strains as well as the stresses appropriately eightfold increase, which right accords with the actual results measured by Zygo Mark interferometer with the error of not over 10%. Therefore some strict temperature-controlled measures are necessary for the scanner.     

Investigation on the properties of high reflective mirror prepared by ion-beam sputtering

The single-sided and dual-sided high reflective mirrors were deposited with ion-beam sputtering (IBS). When the incident light entered with 45°, the reflectance of p-polarized light at 1064 nm exceeded 99.5%. Spectrum was gained by spectrometer and weak absorption of coatings was measured by surface thermal lensing (STL) technique. Laser-induced damage threshold (LIDT) was determined and the damage morphology was observed with Lecia-DMRXE microscope simultaneously. The profile of coatings was measured with Mark III-GPI digital interferometer. It was found that the reflectivity of mirror exceeded 99.9% and its absorption was as low as 14 ppm. The reflective bandwidth of the dual-sided sample was about 43 nm wider than that of single-sided sample, and its LIDT was as high as 28 J/cm2, which was 5 J/cm2 higher than that of single-sided sample. Moreover, the profile of dual-sided sample was better than that of substrate without coatings.     

BL Lac天体Mark 421中心黑洞质量的研究

观测到了BLLac天体Mark421在光学波段的短时标爆发.在26min的爆发期间内,Mark421从B=1576mag到B=1432mag迅速变化了134mag.更为有趣的是观测结果与1996年由Gaidos等观测到的TeVγ射线爆发的结果非常相似,特别是在时标变化和光变曲线等方面两者有相同之处.由上述观测数据结果可以得出:爆发产生于相同的发射区域,这个区域为R=59×1011m,并由此推导出Mark421中心黑洞质量为M=3×106M⊙,这对目前的γ辐射理论模型提出了新的挑战,可以认为Mark421的 关键词：     

2000MarkⅡ OTF测试仪

美国Tropel公司2000Mark Ⅱ型OTF测试仪是目前国内引进的新一代的光学传递函数测试仪。该仪器可测频率高达3000lp/mm,可测波长从紫外0.36μ到远红外12μ物镜口径最大达φ203毫米。用该仪器可测定各种光学镜头、CRT象增强器和纤维面板的OTF。本文简单介绍了2000Mark Ⅱ OTF测试仪的基本性能、结构和计算机软件,对该仪器的接收情况也作了一些说明,并列出了用该仪器测试微光镜头的一些结果。     

地面天文望远镜观测日外行星取得新突破

<正>加利福尼亚州帕萨迪纳市(Pasadena)美国宇航局喷气推进实验室(Jet Propulsion Laboratory)的天文学家斯文(Mark Swain)和美、英、德三国同行共同报告了一项新技     

量子力学偶极求和规则和ψ(3770)的电偶极跃迁

本文对量子力学偶极求和规则进行了一些普遍的讨论.利用这些求和规则估算了ψ(3770)的电偶极跃迁宽度的上限和下限.结果表明.Mark Ⅲ组给出的实验值明显偏大.     

布朗运动和量子力学

1965年R.P.Feynman和A.R.Hibbs的名著《量子力学和路径积分》(“Quantum　Mcchanics　and PathIntegrals”)一书出版.此书中有一练习,让读者计算一个一维以光速运动并可随机反向的粒子随时间的演变.作者出此题的目的或许是让读者检查从该书的前30页所学到的东西.然而此题对于Mark Kac和他的同事来说,则是一个挑战.因为Mark Kac于1959年从布朗运动问题中导出了薛定谔方程,而这个练习则启发了他们要把量子力学和布朗运动在相对论的情形下联系起来. 1984年,《物理评论通讯》(“Physical ReviewLetters”)杂志发表了B.Gaveau 和包括 Mar…     

软饮料可能增加胰腺癌患病风险

尽管胰腺癌并不多见,但是非常致命,95％的患者存活时间不超过5年。明尼苏达大学公共卫生学院副教授佩雷拉（Mark Pereira）等经过调查研究后,认为如果经常饮用含糖碳酸饮料,其中的高糖会增加体内的胰岛素水平,这正是促使胰腺癌细胞生长的诱囚。     

海滩上的非线性海浪

 大多数人认为低振幅海浪非常近似于线性的,然而这却与实际情况相去甚远。美国博尔德市(Boulder)科罗拉多大学(Universityof Colorado) 的阿布洛维提兹(Mark Ablowit)和鲍尔温(DouglasBaldwin)就对墨西哥努埃沃瓦尔塔(Nuevo Vallarta)的两处平坦海滩和美国加利福尼亚州的威尼斯海滩(Venice beach)每天发生的非线性交互作用做了报告。     

美国吉时利（Keithley）仪器公司发布新产品

美国吉时利(Keithley)仪器公司于2005年3月7日在北京国际科技会展中心召开2005年新产品发布会．几十家专业媒体和公司出席．该公司副总裁、业务部总经理Mark A．Hoersten向专业媒体介绍了该公司最新向市场推出的新一代数字源表2600系列和第三代晶圆射频(RF)，并回答了媒体的提问．     

Mark J往事回首

正时间过得真快,一转眼,我们在丁肇中先生领导的Mark J探测器上学习、工作至今已有四十年了。那一年多紧张而有意义的经历令人难忘,对我们以后的工作和生活影响深远。为了纪念这段不平凡的生活,我记录下几件印象深刻的往事。1973年高能所成立之初,所里就很重视对年轻人的培养,开设各种各样的培训活动,如英语学习     

Modulating quantum Fisher information of qubit in dissipative cavity by coupling strength

By using the non-Markovian master equation, we investigate the effect of the cavity and the environment on the quantum Fisher information(QFI) of an atom qubit system in a dissipation cavity. We obtain the formulae of QFI for two different initial states and analyze the effect of the atom–cavity coupling and the cavity–reservoir coupling on the QFI.The results show that the dynamic behavior of the QFI is obviously dependent on the initial atomic states, the atom–cavity coupling, and the cavity–reservoir coupling. The stronger the atom–cavity coupling, the quicker the QFI oscillates, and the slower the QFI decreases. In particular, the QFI will tend to be a stable value rather than zero if the atom–cavity coupling is large enough. On the other hand, the smaller the cavity–reservoir coupling, the stronger the non-Markovian effect, and the slower the QFI decays. In other words, choosing the best parameter can improve the accuracy of the parameter estimation.In addition, the physical explanation of the dynamic behavior of the QFI is given by means of the QFI flow.     

Statistic properties of Fermi gas in a strong magnetic field

Based on the thermodynamic potential function of Fermi gas in a strong magnetic field, using the thermodynamics method, the integrated analytical expressions of thermodynamic quantities of the system at low temperatures are derived, and the effects of the magnetic field on the statistic properties of the system are analysed. It is shown that, as long as the temperature is not zero, the effects of the magnetic field on the thermodynamic quantities of the system contain both oscillatory and non-oscillatory parts. For the non-oscillatory part, compared with the situation of Fermi gas in a weak magnetic field, the influence of the magnetic field on the thermodynamic quantities is not exactly the same. For the oscillatory part, the period and amplitude of the oscillation are all related to the magnetic field. Due to the oscillation, the chemical potential may be greater than Ferim energy of the system, but the oscillation does not affect the thermodynamic stability of the system.     

Effect of electromagnetic boundary condition on dynamo actions

In this paper,based on the mean field dynamo theory,the influence of the electromagnetic boundary condition on the dynamo actions driven by the small scale turbulent flows in a cylindrical vessel is investigated by the integral equation approach.The numerical results show that the increase of the electrical conductivity or magnetic permeability of the walls of the cylindrical vessel can reduce the critical magnetic Reynolds number.Furthermore,the critical magnetic Reynolds number is more sensitive to the varying electrical conductivity of the end wall or magnetic permeability of the side wall.For the anisotropic dynamo which is the mean field model of the Karlsruhe experiment,when the relative electrical conductivity of the side wall or the relative magnetic permeability of the end wall is less than some critical value,the m=1(m is the azimuthal wave number)magnetic mode is the dominant mode,otherwise the m=0 mode predominates the excited magnetic field.Therefore,by changing the material of the walls of the cylindrical vessel,one can select the magnetic mode excited by the anisotropic dynamo.     

Effect of the Aharonov-Bohm flux on the magnetic gap soliton in antiferromagnetic chain

Employing the double-sublattice, the coherent state ansatz, and the time-dependent variational principle, we have studied the effects of the Aharonov-Bohm flux on the soliton in one-dimensional antiferromagnetic chain. The results show that the Aharonov-Bohm flux have an effect on the peak, the width, the energy and the spatial configuration of the spin of the soliton.     

Collisional Effects on Drift Wave Microturbulence in Tokamak Plasmas

Collisional effects on the microturbulence, excited by the electrostatic drift-wave instability, are investigated through first-principle large scale gyrokinetic particle simulations using the realistic discharge parameters of the DIII–D Tokamak. In the linear simulations, the growth rates of the drift waves are decreased by the collisions compared to the collisionless simulations in the lower and higher T_e plasmas. In the lower T_e plasma, the collisions can promote the transition of the drift wave regime from the TEM-dominant instability to the ITG-dominant instability. The zonal flows are excited by the microturbulence and work as a modulation mechanism for the microturbulence in the nonlinear simulations. Microturbulence can excite high frequency zonal flows in the collisionless plasmas, which is in agreement with the theoretical work. In the lower T_e plasma, the collisions decrease the microturbulence in the nonlinear saturated stage compared to the collisionless simulations, which are beneficial for the plasma confinement. In the higher T_e plasma, the final saturated microturbulence shows a slight change.     

Oscillating Propagation of Kink in Nondissipative Frenkel-Kontorova Chain Due to External DC Force

We report the oscillating propagation of kink in a nondissipative Frenkel-Kontorova （FK） chain driven by external DC force, which is different from the usual propagation of localized modes with equal speed. When the kink moves in the opposite direction of the external DC force, the kink will be accelerated and the potential of the FK chain in the external force field is transformed to be the kinetic energy of the kink. If the kink reaches the boundary of the FK chain, the kink will be bounced back and moves in the opposite direction, then the kink will be decelerated gradually and the kinetic energy of the kink ＆ transformed to be the potential of the FK chain in the external force field. If the speed of the kink reaches zero, the kink will move in the opposite direction again driven by the external DC force, and a new oscillating cycle begins. Simulation result demonstrates exactly the transformation between the kinetic energy of the kink and the potential of the FK chain in the external force field. The interesting energy exchange is induced by the special topology of kinks, and other localized modes, such as breathers and envelope solitons, have no the interesting phenomenon.     

First Integrals and Integral Invariants of Relativistic Birkhoffian Systems

For a relativistic Birkhoflan system, the first integrals and the construction of integral invariants are studied. Firstly, the cyclic integrals and the generalized energy integral of the system are found by using the perfect differential method. Secondly, the equations of nonsimultaneous variation of the system are established by using the relation between the simultaneous variation and the nonsimultaneous variation. Thirdly, the relation between the first integral and the integral invariant of the system is studied, and it is proved that, using a t~rst integral, we can construct an integral invarlant of the system. Finally, the relation between the relativistic Birkhoflan dynamics and the relativistic Hamilton;an dynamics is discussed, and the first integrals and the integral invariants of the relativistic Hamiltonian system are obtained. Two examples are given to illustrate the application of the results.     

Effect of driving frequency on electron heating in capacitively coupled RF argon glow discharges at low pressure

A one-dimensional(1D) fluid model on capacitively coupled radio frequency(RF) argon glow discharge between parallel-plates electrodes at low pressure is established to test the effect of the driving frequency on electron heating. The model is solved numerically by a finite difference method. The numerical results show that the discharge process may be divided into three stages: the growing rapidly stage, the growing slowly stage, and the steady stage. In the steady stage,the maximal electron density increases as the driving frequency increases. The results show that the discharge region has three parts: the powered electrode sheath region, the bulk plasma region and the grounded electrode sheath region. In the growing rapidly stage(at 18 μs), the results of the cycle-averaged electric field, electron temperature, electron density, and electric potentials for the driving frequencies of 3.39, 6.78, 13.56, and 27.12 MHz are compared, respectively. Furthermore,the results of cycle-averaged electron pressure cooling, electron ohmic heating, electron heating, and electron energy loss for the driving frequencies of 3.39, 6.78, 13.56, and 27.12 MHz are discussed, respectively. It is also found that the effect of the cycle-averaged electron pressure cooling on the electrons is to "cool" the electrons; the effect of the electron ohmic heating on the electrons is always to "heat" the electrons; the effect of the cycle-averaged electron ohmic heating on the electrons is stronger than the effect of the cycle-averaged electron pressure cooling on the electrons in the discharge region except in the regions near the electrodes. Therefore, the effect of the cycle-averaged electron heating on the electrons is to "heat" the electrons in the discharge region except in the regions near the electrodes. However, in the regions near the electrodes, the effect of the cycle-averaged electron heating on the electron is to "cool" the electrons. Finally, the space distributions of the electron pressure cooling the electron ohmic heating and the electron heating at 1/4 T, 2/4 T, 3/4 T, and 4/4 T in one RF-cycle are presented and compared.     

Deformation analysis of an incompressible composite cylindrical tube subjected to end axial loads and internal constraint

In this paper,the problem of axially symmetric deformation is examined for a composite cylindrical tube under equal axial loads acting on its two ends,where the tube is composed of two different incompressible neo-Hookean materials.Significantly,the implicit analytical solutions describing the deformation of the tube are proposed.Numerical simulations are given to further illustrate the qualitative properties of the solutions and some meaningful conclusions are obtained.In the tension case,with the increasing axial loads or with the decreasing ratio of shear moduli of the outer and the inner materials,it is proved that the tube will shrink more along the radial direction and will extend more along the axial direction.Under either tension or compression,the deformation along the axial direction is obvious near the two ends of the tube,while in the rest,the change is relatively small.Similarly,for a large domain of the middle part,the axial elongation is almost constant;however,the variation is very fast near the two ends.In addition,the absolute value of the axial displacement increases gradually from the central cross-section of the tube and achieves the maximum at the two endpoints.