Focusing-defocusing phenomena of radio echo signal after passage of the morning solar terminator

Summary Campaign results of high-repetition ionospheric soundings, performed at the ionospheric station of Rome using a Digisonde 128P, are presented. We introduce an index derived from run rapid ionograms that can be used to detect oscillations of isodensity surfaces ofF ionospheric region started by morning solar terminator.     

抽样调查中最佳测量次数的确定

现场抽样调查中，由于测量误差的存在，使得所测变量实测值的方差增大，通过增加每个体的测量次数可以控制测量误差，但这样每个体调查费用增大。本文对测量信度Ｒ，每个体测量次数ｍ与相应所需的样本含量ｎｍ、调查费用Ｔｎ的关系进行了探讨，并介绍了如何根据Ｒ，及每个体测量费用占其总费用构成比Ｃ，确定最佳测量次数ｍ值，以达到最佳控制调查费用的目的，这对我们在大型现场调查中进行经济效益分析具有重大的理论指导意义。     

On the Solvability of the Multidimensional Version of the First Darboux Problem for a Model Second-Order Degenerating Hyperbolic Equation

A multidimensional version of the first Darboux problem is considered for a model second-order degenerating hyperbolic equation. Using the technique of functional spaces with a negative norm, the correct formulation of this problem in the Sobolev weighted space is proved.     

电子直线加速器磁控管频率稳定的自适应线性神经元方法

 电子直线加速器电子束能量的稳定与否取决于功率源工作频率的稳定性,磁控管在短时间内的散谱和轻微跳谱造成稳频系统的控制精度下降,最后电子束的扫描均匀度下降。引入自适应线性神经元方法(ADALINE)和噪声对消技术以消除对工作频率长期稳定性的影响,从而保证了电子束的扫描均匀度。     

How should one define a (weak) crystal?

We compare two proposals for the study of positional long-range order: one in terms of the spectrum of the translation operator, the other in terms of the Fourier spectrum. We point out that only the first one allows for the consideration of molecular, as opposed to atomic, (weakly) periodic structures. We illustrate this point on the Thue-Morse system.     

Some remarks on the Jensen-Hadamard inequalities and applications

We provide some inequalities and integral inequalities connected to the Jensen-Hadamard inequalities for convex functions. In particular, we give some refinements to these inequalities. Some natural applications and further extensions are given.

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Sunto Forniamo alcune diseguaglianze e diseguaglianze integrali connesse alle dise-gueglianze di Jensen-Hadamard per funzioni convesse. In particolare, diamo qualche miglioramento di queste diseguaglianze. Alcune applicazioni naturali ed ulteriori estensioni sono date.

     

关于可达矩阵的求法探讨

在《离散数学》、《图论》课程中 ,用矩阵表示图时 ,涉及到一类重要的矩阵——可达矩阵 ,它是判别图中任意两点是否有通路的重要手段 ,也是求强分图的重要方法 ,但是可达矩阵的求法比较复杂 .本文针对这一问题 ,对可达矩阵的求法进行了改进 ,提出了一种简单可行的算法 .     

一类雨量预报准确性评价方法

给出了一种利用网格点的预报雨量来模拟区域内任一点预报雨量的方法,建立了预报雨量函数,进而得出预报雨量与实测雨量的整体偏方差的数学模型;利用QPF方法建立出准确率、预报效率、空报率、漏报率等评价预报方法优劣指标的数学模型,并对两种预报方法得出的数据进行了计算,得出上述模型中的数值如下:方案方法总体偏方差预报准确率漏报率空报率预报效率方法1 0.99987×10679.431%11.463%25.621%62.256%方法2 1.00518×10657.509%26.976%31.705%58.936%比较这些指标,可得第一种预报结果较好.     

Explicit Confinement Effect on the Helicity Amplitudes of the Low-Lying Nucleon Resonances

Calculations of helicity amplitudes for the low-lying nucleon resonances are displayed based on a non-relativistic constituent quark model with a harmonic oscillator confinement. The explicit effect of quark confinement isshown. Our results show that the effect plays sizable role on some transition amplitudes of S11(1535) and D13(1520)resonances. The effect on the △(1232) transition amplitudes islessthan 10%. However, the effect on the Roper resonanceis remarkable but is inconclusive.