星载太阳辐照度光谱仪短时高精度太阳预报

为了在有限的太阳观测窗口内获得高质量的太阳光谱数据,需保证太阳进入观测窗口时仪器已完成自身预热。为保证仪器预热时间的一致性,需在轨实时预报预热开始时刻,需对每轨太阳开始进入仪器观测窗口的时间进行短时间高精度预报。详细介绍了一种由卫星平台当前广播时间和轨道瞬根推导预报时刻太阳角度的方法。利用该方法预报某一太阳同步轨道卫星本体坐标系下的太阳角度,并将预报结果与STK仿真结果进行比对。该预报方法在预热时间内的最大角度误差为0.5°,导致预热时间最大偏差为20 s,满足1 min的指标要求。分析了预报方法中的主要误差来源,为后续卫星载荷的在轨太阳角度短期预报提供了借鉴与参考。     

电子镇流器进一步节能的实验研究

对预热启动式电子镇流器进一步节能的途径和实验方法进行了研究，从实验中得出实验数据和结论。     

低速过滤燃烧火焰面倾斜动力学因素数值预测

采用数值手段对贫甲烷/空气预混气体低速过滤燃烧火焰面倾斜动力学因素进行数值预测。确认多孔介质内局部孔隙率分布不均匀性、初始预热段预热不均匀性等因素是火焰面倾斜不稳定性发生的动因。火焰面倾斜演变的快慢与孔隙率分布不均匀性及初始预热段预热不均匀性具有相关性,孔隙率分布及初始预热越不均匀,火焰面倾斜不稳定性发展越快。此外,将数值预测结果与实验结果分析比较,确认实验中火焰面倾斜不稳定性发生及发展是多因素叠加扰动的结果。     

焊接现场射线检测技术应用分析

某产品的焊接须预热到300℃后进行，焊后采用自然冷却，再进行X射线照相检测。传统的射线照相检测过程费时费力，一定程度制约了产品生产进度。如能在焊接现场进行实时的射线检测，则可及时发现焊接中的缺陷并进行相应的处理，免除了冷却、送检、返修、再预热及胶片处理等时间，从而大大提高生产效率。文中对射线检测的数字化技术应用的不同方式（CR、DR）进行了对比分析，认为采用DR技术（射线扫描探测器）可有望提高检测的效率。     

烧蚀RT不稳定性非线性过程模拟

重点研究了不同预热对烧蚀RT弱非线性模耦合的影响。首先不同预热情况烧蚀RT不稳定性的线性增长率曲线明显不同。不同预热情况的模拟结果都表明：烧蚀RT的模耦合系数是k／kc的函数，二次和三次谐波的产生系数C（k）和D（k）遵从定标关系C（k）：c1（1-c2k/kc），D（k）=d1-d2k/kc＋d3（k/kc）^2。弱预热和中等预热情况，二次谐波的产生系数约只有经典RT的50％，三次谐波的产生系数约只有经典RT的20％。两体模耦合起主要作用，n次高次谐波可近似看作是由（”一1）次两体模耦合产生的。由于烧蚀RT不稳定性两体模耦合系数小于1，所以高次谐波的产生系数很快衰减。由于非线性作用变弱，单模扰动的非线性饱和阈值明显增大，意味着基模有较长时间的线性增长，另外，向长波长方向的模耦合系数明显大于经典尺丁不稳定性数值，因此，烧蚀RT非线性模耦合容易形成长的尖顶，从而对点火构成严重威胁。     

双模瑞利-泰勒不稳定性的预热烧蚀效应研究

针对双模扰动下的烧蚀瑞利-泰勒不稳定性增长问题,采用高精度的数值计算方法,研究了不同预热程度下模耦合产生的多个高次谐波幅值的发展和演化问题。研究表明,三种预热烧蚀条件下,当扰动基模满足长波与短波耦合方式时,谐波中的长波模态占主导,而短波模发展明显受到抑制;当满足短波与短波耦合时,耦合结果带来了许多新的增长较快的长波模态,此时短波模增长呈现小幅震荡形式。比较两种耦合方式可以发现,长波结构在烧蚀瑞利-泰勒不稳定性弱非线性阶段都占主导地位,尤其是短波与短波耦合中气泡与尖钉表现出不同于两个基模的长波模结构。进一步分析预热效应对模耦合增长的影响,发现预热程度越强就越能削弱耦合谐波的增长,这说明预热对烧蚀瑞利-泰勒不稳定性具有致稳作用,这对惯性约束聚变工程中控制烧蚀瑞利-泰勒不稳定性发展具有重要意义。     

预热效应影响下冲击波速度推算方法

介绍了超高压条件下应用于透明材料中冲击波速度直接测量的成像型速度干涉仪技术。利用成像型速度干涉仪技术研究了间接驱动实验中产生的预热效应对冲击波速度计算的影响。对预热效应出现的时间点进行了分析,发现在辐射温度高于160 eV以后,不能从现有速度干涉仪系统获得的实验结果直接反演出冲击波速度。对实验数据进行了处理,获得了预热出现时间点的实验数据,发现预热效应出现在方波激光脉冲平台期到达时刻,在激光最强处达到最大,而且在激光脉冲平台期结束后,预热效应可以逐渐恢复。实验发现,对辐射温度高于160 eV获得的实验结果,可以从条纹断点直接外推,得到冲击波减速数据。讨论了条纹外推方法处理间接驱动条件下方波打靶时,使用固体无机透明材料作为窗口获得的实验结果。     

低温化学影响下的火焰不稳定性研究

考虑详细化学反应及输运过程,对不可压N-S方程直接数值求解,研究了低温化学影响下的火焰水力学及胞状不稳定性。结果表明,预热后已发生低温化学反应的混合气,其火焰的扰动增长率明显大于未发生低温反应的混合气火焰。通过对预热后混合气火焰的关键参数分析,发现和未预热混气火焰相比其无量纲释热量、Lewis数及Zeldovich数都显著减小。依据已有理论可知,在Lewis数大于1的条件下,上述参数的减小将使得胞状不稳定性对扰动增长的抑制作用减弱。因此,预热后火焰的增长率明显增大。同时,在低温反应中,大量自由基和其它小分子的形成,使得预热后混合气火焰Lewis数减小,从而其火焰胞状结构的深度和高度都变小。     

初中生解题中的典型错误例析

初中生解题中的典型错误例析周黔坚（广西梧州地区教研室梧州）研究物理解题中的错误和其克眼办法，是有利于学生分析其错误原因，促进学生学会全面地、审慎地分析题设条件和正确理顺解题思路，达到加深对物理概念的理解、提高分析和解决物理问题能力的目的。初中生在解答...     

采用非接触式预热对模压红外透镜雾斑的影响

非球面红外透镜模压成型时,通过提高成型阶段温度可缩短透镜压切时间,从而提高模压效率,但易在透镜表面产生雾斑,像造透镜不良。本文通过对透镜雾斑的形成机理进行分析,采用一种非接触式预热模压工艺降低透镜雾斑的形成,并在多站式模压机上进行模压实验,使用能谱仪对雾斑的元素进行检测和分析。在本次模压实验中采用非接触式预热方式,当预热间隙为1 mm时将成型温度由206℃提升至211℃,透镜表面无雾斑生成,并使压切时间缩短了21 s。实验结果表明,在多站式模压中采用非接触式预热方式,可以有效消除透镜雾斑的形成。检测结果表明,成型阶段透镜材料的挥发对雾斑的形成起主导作用。     

Finite-difference time-domain technique as an efficient tool for calculating the regularized Green function: applications to the local-field problem in quantum optics for inhomogeneous lossy materials

The calculation of the local density of states (LDOS) in lossy materials has long been disputed due to the divergence of the homogeneous Green function with equal space arguments. For arbitrary-shaped lossy structures, such as those of interest in nanoplasmonics, this problem is particularly challenging. A nondivergent LDOS obtained in numerical methods such as the finite-difference time-domain (FDTD) technique, at first sight appears to be wrong. Here we show that FDTD is not only an ideal choice for obtaining the regularized LDOS, but it can address the local-field problem for any lossy inhomogeneous material. We exemplify the case of a finite-size photon emitter (e.g., a single quantum dot) embedded within and outside a lossy metal nanoparticle and show excellent agreement with analytical results.     

高调谐BST薄膜制备及介电性能研究

用改进的溶胶凝胶(sol-gel)法逐层制备钛酸锶钡(Ba_0.6Sr_0.4TiO₃, BST)薄膜,研究中间热处理(preheating,PT)对薄膜结构及介电性能的影响.X射线衍射(XRD)表明,BST薄膜主要沿(110)方向生长,对应立方钙钛矿结构,PT使晶化增强.X射线光电子能谱(XPS)表明,PT促使表面非钙钛矿结构向钙钛矿结构转变.原子力显微镜(AFM)和介电性能测试表明,随着PT频次的增加,薄膜形貌改善,表面粗糙度降低,介电调谐 关键词： 中间热处理 高调谐 溶胶凝胶法 钛酸锶钡     

Three-Body Phase Shift in One-Dimensional 2 + 1 Scattering

For a model of three particles on a line, subject to attractive delta-function interactions, we consider the phase shift. We do this from the point of view of the calculation of the S-matrix in a hyperspherical adiabatic basis (an adiabatic S-matrix), and for energies ranging from the (negative) energy of the two-body bound state to a total energy of zero. We derive analytical expansions and present numerical work, for different approximations, and compare with the exact results that we obtain from the work of McGuire, whose model we have borrowed. We show that the simplest adiabatic approximation gives results that are qualitatively wrong, but that better approximations yield, for most of our range, excellent agreement with the exact result. Understanding the threshold behaviour, however, requires a zero-energy three-body bound state, or resonance, previously unsuspected for this model. The methods developed for the case of the simplest adiabatic approximation also yield threshold and low-energy results applicable to the two-body problem in two dimensions. Received December 23, 1996; revised May 13, 1997; accepted for publication June 19, 1997     

Analytical and statistical calculation of gamma dose rate for the accident of losing the shield for Tehran Research Reactor

In this paper we study the analytical and statistical results of estimating the gamma dose rate at pool access floor in TRR when the core shield accidentally decreases to some non-permitted levels. Due to the risk of experimental techniques, we use the analytical and statistical methods. In normal conditions (no risk),the discrepancies between experiment and two methods are justified and it is found that for such problems we have to normalize these methods to experimental results as follows: the analytical method by factor 0.13 and MCNP by 1.7.     

Analytical and statistical calculation of gamma dose rate for the accident of losing the shield for Tehran Research Reactor

In this paper we study the analytical and statistical results of estimating the gamma dose rate at pool access floor in TRR when the core shield accidentally decreases to some non-permitted levels. Due to the risk of experimental techniques, we use the analytical and statistical methods. In normal conditions (no risk), the discrepancies between experiment and two methods are justified and it is found that for such problems we have to normalize these methods to experimental results as follows: the analytical method by factor 0.13 and MCNP by 1.7.     

Symplectic integration of nonlinear Hamiltonian systems

There exist several standard numerical methods for integrating ordinary differential equations. However, if one is interested in integration of Hamiltonian systems, these methods can lead to wrong results. This is due to the fact that these methods do not explicitly preserve the so-called ‘symplectic condition’ (that needs to be satisfied for Hamiltonian systems) at every integration step. In this paper, we look at various methods for integration that preserve the symplectic condition.     

Production of high quality shocks for equation of state experiments

In this paper we describe the quality requirements that a shock wave must fulfil to make equation of state (EOS) measurements possible: planarity, no-preheating and stationarity of the shock. Experimental measurements have been performed at the Max Planck Institut für Quantenoptik (Garching). We also present simple analytical models that allow to verify shock stationarity and absence of preheating. Received 17 June 2002 Published online 21 January 2003 RID="a" ID="a"e-mail: batani@mib.infn.it RID="b" ID="b"Present address: Pro-beam, Behrinsta?e 6, 85152 Planegg b. München, Germany. RID="c" ID="c"UMR 7605     

Interference of traveling nondiffracting beams

We study numerically the interference resulting from the superposition of two Bessel beams propagating in free space. We discuss how to obtain such beams and show the existence of the self-imaging effect during propagation. The evolution of the superimposed Bessel beams is analyzed on the basis of the evolution of the individual beams. Our exact numerical predictions contradict previous approximated analytical treatments, showing that they can lead to quantitatively wrong results and misleading conclusions.     

原子吸收光谱仪的升级改造

本文对原子吸收光谱仪的升级改造进行了探索，使用先进的计算机控制技术，取代原仪器故障频繁的数据处理及记录部分，使升级改造后的仪器在分析精度，分析速度，自动化程度等方面大大提高，该技术一个突出的特点是：软件全部在中文Windows 下操作，更适合国情。     

Effect of spontaneous magnetic fields on energy transfer by fast electrons in spherical laser targets

It is shown that the spontaneous magnetic fields generated due to development of hydrodynamic instability in the process of compression of spherical laser targets can substantially affect the energy transfer by fast electrons. The analytical solutions to the kinetic equation for the distribution function of fast electrons are obtained taking into account the reflection from the region of the magnetic-field localization. On the basis of these solutions, the effect of the spontaneous magnetic fields on the specific energy released by the fast electrons per unit mass and on preheating of the target material being compressed is investigated.