基于多视场星点椭圆率的望远镜主动准直方法

光学元件的准直失调会引起天文望远镜在观测过程中的像质退化,该问题在大口径快焦比的天文光学系统中更为突出。针对此问题,本文提出一种用于望远镜日常观测过程中的主动准直方法,通过星像解算实时校正副镜位置及姿态达到维持望远镜像质的目的。该方法基于多视场星点椭圆率,利用粒子群优化算法迭代求解望远镜光学元件失调量,从而校正由光学元件失调引起的低阶像差。利用1.6 m多通道测光巡天望远镜光学系统进行模拟仿真,求解副镜失调量残余误差小于1%,在系统设计公差范围以内。利用南极巡天望远镜AST3-3模拟及实验验证,表明该方法可高精度求解望远镜光学元件的失调误差。     

一种分析望远镜热稳定腔的新方法

本文报道了一种分析望远镜热稳定腔的新方法——组合透镜法。运用这种方法,成功地实现了Nd:YAG脉冲激光器的稳定而大体积TEM_(00)模运转,在1～10pps重复率范围内,振荡级的单脉冲输出能量达250mJ,输出能量起伏小于±2%。     

天基望远镜探测器组件热电制冷系统设计与试验

天基空间望远镜探测器必须采用主动制冷方式以满足其噪声抑制需求.为此,采用热电制冷为核心技术,开展了探测器热电制冷器封装设计、热电制冷器热排散系统设计、热电制冷控制系统设计,并从抑制寄生漏热、降低热电制冷器热排散路径热阻两方面进行了优化,以减小热电制冷器输入功率及辐射散热面积.根据帕尔帖效应、焦耳效应、傅里叶效应,获得了净制冷量、热端散热热阻、热端边界温度等环境特性参数与热电制冷器输入电流、电压、功率等工作特性参数间的关系,并分析了制冷热负荷、热端散热热阻与热电制冷器输入功率间的敏感度.研制了望远镜鉴定产品,并开展了真空热平衡试验.试验结果表明系统设计合理有效,能够将探测器制冷至-75℃温度水平,稳定度可达到±0.2℃.基于环境条件及热电制冷器工作参数等试验数据,对比并修正了热分析模型.研究结果可为类似空间望远镜热电制冷系统的研制提供参考和借鉴.     

基于本征系数的大口径望远镜失调量解算

针对大口径望远镜光学系统内部空间限制的特点,为了实现失调量校正,提出了一种基于本征系数的失调量解算方法.该方法首先利用波前曲率传感器的原理,通过交替测量前后离焦面的方式采集光斑图.然后,利用无需分区探测的本征函数法进行波前重构,利用本征系数来表征系统波像差,并依据失调量建立灵敏度矩阵模型.最后,根据失调状态与理想状态的本征系数即可求解出失调量.与其他技术途径相比,该方法具有无需添加光学元件、无需分区探测、运算简单的特点.主镜直径为1.8m的望远镜实验结果表明,当次镜偏心距离范围为--0.9～0.9 mm、倾斜角范围为--0.2°～0.2°时,利用本征系数灵敏度矩阵法得到的计算值的误差均小于10％,对大口径望远镜中的应用具有一定的意义.     

大口径望远镜结构热分析

为了评估温度对望远镜的影响,针对某地基光电望远镜,建立了包括光学组件,跟踪架结构以及电控设备等在内的有限元热模型.在传导、对流、辐射以及热流等不同热环境下进行热分析,计算了望远镜光机结构的时间和空间温度分布.根据温度分布进行了热-弹性分析,得出了望远镜结构的热变形.分析表明:温度变化对望远镜跟踪架以及主光学系统的影响很大,对主次镜造成的相对位移达到毫米级,必须进行严格控制.最后从防护圆顶、跟踪架以及主镜等方面入手给出了热控设计方案.     

月基望远镜热设计及热分析

为了利用月球观测地球等离子体层的优势,开展了月基望远镜的研究,并对其进行了热设计和热分析.分析了月基望远镜所处的空间环境.对望远镜各个部分进行了热设计;采用被动热控措施控制望远镜的温度水平,降低空间环境的影响;采用热疏导的方式对探测器进行散热.根据月基望远镜的空间环境、结构特点,以及采取的热控措施,在I-DEAS/TM...     

光学天文望远镜的足迹

文章以较为轻松的笔调概述了光学天文望远镜400年的发展史.全文分7个部分,内容包括望远镜的诞生、像差和消色差透镜、传统的反射望远镜和折射望远镜、施密特望远镜的作用、当代巨型望远镜的出现、空间望远镜,以及对月基望远镜的憧憬.     

基模动态稳定望远镜谐振腔

本文使用等价腔和传播矩阵方法,在一般情况下推导出了望远镜腔的基模热稳条件,该表示式简单而又严格,还易于推广到含热透镜多元件腔的一般情况,并与用近似方法所得结果作了比较和讨论。     

氩离子激光器同步泵浦染料激光器

研究了氩离子激光器的声光锁模参数.对4880(?)和5145(?)均获得了较稳定的锁模运转.锁模平均功率～300mW,脉冲宽度～200ps,脉冲强度起伏小于5%.用这台氩激光器同步泵浦一台折迭式象散补偿腔染料激光器,实现了同步锁模输出.在5840(?)处,其脉冲宽度小于10ps,平均功率～20mW.波长调谐范围是5700～6200(?),并着重研究了腔长或频率失调对锁模的影响.     

多模热不灵敏腔

使用ABCD定律和g~*g＇参数等价腔对多模工作下的热不灵敏腔作了理论研究.在钕玻璃激光器作实验证实了有关的理论结果.     

光谱法研究葫芦[6]脲与土霉素的分子识别作用

采用荧光光谱和紫外光谱研究葫芦[6]脲(CB[6])与土霉素(OTC)的分子识别作用。实验结果表明,随着主体分子的加入,OTC荧光强度和紫外吸收强度均增强,说明主客体之间发生了相互作用;进一步通过荧光光谱、紫外光谱和直线拟合法(Benesi-Hildebrand)确定了CB[6]与OTC形成1∶1型的包结物;在酸性环境下CB[6]与OTC能形成1∶1型的稳定的包结物,在碱性环境下不能形成稳定的包结物;同时计算了主客体在298,308和328 K下包结的平衡常数K_s和CB[6]与OTC的分子识别过程的熵变、焓变和吉布斯自由能变。不同温度下的吉布斯自由能变ΔG均小于0,而熵变和焓变为正值,其包结过程是疏水作用力驱动且自发的吸热的过程。     

Relativistic Diffusion in Gödel’s Universe

K. Gödel [G1] published his exact solution to Einstein’s field equations in 1949. On the other hand, a general Lorentz invariant operator, associated to the so-called “relativistic diffusion”, and making sense in any Lorentz manifold, was introduced recently by Franchi-Le Jan in [F-LJ]. Here is proposed a study of the relativistic diffusion in the framework of Gödel’s universe, which contains matter. Such study is related to the determination of a boundary for this non-causal universe.     

A new trial equation method for finding exact chirped soliton solutions of the quintic derivative nonlinear Schrödinger equation with variable coefficients

In this work, we propose an efficient generalization of the trial equation method introduced recently by Liu [Appl. Math. Comput. 217 (2011) 5866] to construct exact chirped traveling wave solutions of complex differential equations with variable coefficients. The effectiveness of the proposed method has been tested by applying it successfully to the quintic derivative nonlinear Schrödinger equation with variable coefficients. As a result, a class of chirped soliton-like solutions including bright and kink solitons is derived for the first time. Compared with previous work of Liu in which unchirped solutions were given, we obtain exact chirped solutions which have nontrivial phase that varies as a function of the wave intensity. These localized structures characteristically exist due to a balance among the group-velocity dispersion, self-steepening and competing cubic-quintic nonlinearity. Parametric conditions for the existence of envelope solutions with nonlinear chirp are also presented. It is shown that the chirping can be effectively controlled through the variable parameters of group-velocity dispersion and self-steepening.     

Eigenstate Possessing ODLRO for Hubbard Model

The Hubbard model is the simplest model expected to incorporate the essential feature of trong correlations. Since the discovery of high temperature suqerconductivity^[1], the Hubbard model has received renewed attention especially motivated by Anderson's^[2] suggestion that such phenomena in oxides can be understood already within this simplest model. In spite of the great amount of effort in solving this model, very few precise results are available, except in one dimension where many properties are accessible through the exact Bethe ansata solution. Recently, C.N. yang^[3] has constructed many eigdnfunctions of the simplest Hubbard model in three dimensions and these eigenfunctions possess off-diagonal-long-range-order (ODLRO).     

不同时效状态的含铜4%的铝合金在疲劳载荷下溶质原子与位错的交互作用

为了进一步研究在疲劳载荷下含铜4％的铝合金中的位错钉扎过程,进行了经过不同时效的试样的扭转疲劳试验,测定了经过各种应力循环数N以后的滞后迴线的形状和面积,从而算出了在每次循环中的能量消耗ΔE和最大抗扭矩T_m。所选择的时效温度和时效时间是使试样中分别有G.P.[1]区,G.P.[2]区,θ′相和稳定的θ相出现。把所得的ΔE-N曲线和T_m-N曲线的变化情况作比较时可以看出,在疲劳载荷的起始阶段引起位错钉扎的并不是由于相变产物如G.P.[1]或[2]区的作用。比较并分析了在各种时效状态下的第一周能量消耗值(ΔE)₁的变化,结果指出,在所研究的铝铜合金的情形,产生ΔE的原因是由于在位错附近的点阵中有起伏的内应力场出现,因为位错在这种内应力场中往复运动需要作功。产生这种起伏的应力场的因素有点缺陷(空位和溶质原子)、原子簇、G.P.[1]区和G.P.[2]区,或者其他种不在位错线上聚集或成核的缺陷。根据上述分析,可以认为,在疲劳载荷中,使位错钉扎的是由于溶质原子气团的形成。溶质原子在疲劳过程中通过空位的帮助进入位错,形成气团,使位错被钉扎。被钉扎的位错的动性减低,因而ΔE下降。在时效过程中,在位错线上成核的θ′和θ相,对于位错线也起着一定的钉扎作用。由上述的图象还可以推知,G.P.[1]区和G.P.[2]区不是在位错线上成核的,而θ′相和θ相则是在位错线上成核的。     

Scalings in circle maps II

In this paper we consider one parameter families of circle maps with nonlinear flat spot singularities. Such circle maps were studied in [Circles I] where in particular we studied the geometry of closest returns to the critical interval for irrational rotation numbers of constant type. In this paper we apply those results to obtain exact relations between scalings in the parameter space to dynamical scalings near parameter values where the rotation number is the golden mean. Then results on [Circles I] can be used to compute the scalings in the parameter space. As far as we are aware, this constitutes the first case in which parameter scalings can be rigorously computed in the presence of highly nonlinear (and nonhyperbolic) dynamics.     

Dynamics of bright soliton bound states in (2+1)-dimensional multicomponent long wave-short wave system

In this paper, we construct the bright-soliton bound states of an integrable (2 + 1)-dimensional multicomponent long wave-short wave resonance interaction (LSRI) system by using the exact bright-soliton solutions obtained in Ref. [24] and analyze their interesting collision dynamics. We show that the beating and breathing oscillations of the bound solitons can be controlled by tuning the polarization parameters. Also, we explore the interaction between the bound-soliton and a standard soliton. We also point out that the two bound-soliton state seems to be robust against collision with a standard soliton and remain to be bounded even after collision.     

Molecular structure and vibrational spectra of [2-Oxo-2-(4-acetyl) phenyl amino] ethylene methacrylate by density functional theory and ab initio Hartree–Fock calculations

The molecular geometry and vibrational frequencies of the [2-Oxo-2-(4-acetyl) phenyl amino] ethylene methacrylate (APEMA) were examined theoretically using the Hartree–Fock and Density function method (B3LYP) with 6-31G(d) basis set. The calculated geometrical parameters of the investigated molecule were compared with experimental data. Both the calculated structural parameters and vibrational frequencies are in good agreement with the available experimental data.     

The modified multiple (G ′ / G )-expansion method and its application to Sharma–Tasso–Olver equation

The modified multiple ( \(G^{\prime }/G\) )-expansion method is proposed in this paper to construct exact solutions of nonlinear evolution equations. The validity and advantage of the proposed method are illustrated by its application to the Sharma–Tasso–Olver equation. As a result, various exact solutions including hyperbolic functions, trigonometric functions and their mixture with parameters are obtained. When some parameters are taken as special values, the known double solitary-like wave solutions are derived from the double hyperbolic function solution. It is shown that the method introduced in this paper has general significance in searching for exact solutions to the nonlinear evolution equations.     

Theory of multiple scattering

Consideration is given to problems of obtaining exact and approximate solutions of kinetic equations in the multiple scattering problem. For cross sections which are rational functions of χ² (χ = 2sin(δ/2), δ is the scattering angle) exact solutions are obtained as a series in terms of Legendre polynomials. The limits of validity of the kinetic equation for the distribution function in terms of the variable q = 2sin(?/2) are refined [1] and the solutions of this equation are compared with the exact solutions of the Rutherford and Mott cross sections. The problem of convergence of approximate solutions in the form of a series in terms of Legendre polynomials and a series in powers of 1/B is solved. These approximations are obtained and their limits of validity are determined.