级数判敛法在应用中应注意的问题

级数理论是数学分析的重要组成部分,它是研究函数的一个重要工具.指出证明∑∞n=1an(an 0)收敛和∑∞n=1un(x)一致收敛时应注意的几个问题.     

级数的一个通项公式

给定级数的前任意有限项,级数并不能被唯一地确定,因此其敛散性由给定的前有限项而确定出的不同通项表达式而异。该文介绍了关于级数的一个通项公式与两个结论。     

三维空间场可引入几个"度”

对微分的外乘积、外微分形式做了初步的介绍,运用它同三维空间的梯度、旋度、散度相对应。指出在三维空间中只可引入梯度、旋度、散度、除此之外不可能再引入其它与之相对应的“度”。     

椭圆型偏微分方程解的研究

利用泛函分析理论证明椭圆型方程弱解的存在性。     

Growth, structure and upconversion mechanisms of Ba2ErCl7 crystal

The methods to grow a novel upconversion crystal Ba₂ErCl₇ are reported in this note. Ba₂ErCl₇ material was synthesized with Er₂O₃, BaCl₂·2H₂O and NH₄Cl by using a so-called “direct synthesis method”. High quality Ba₂ErCl₇ single crystals with size up to 4 mm×8 mm×15 mm were grown by using the Czochralski and the Bridgman methods. Intense yellow-green luminescence was detected when the crystal was pumped by an 803 laser diode (LD). Transmittance spectrum was measured by using HITACH U-3500 spectrophotometer at room temperature for the first time, in which one can see that the transmittance is high in the range from 350 to 1 600 nm and the cut-off wavelength of the crystal was 230 nm. The upconversion mechanisms were discussed.     

Testing relative evolutionary rates and estimating divergence times among six genera of Rhizophoraceae using cpDNA and nrDNA sequences

The molecular phylogenetic trees of 10 species representing 6 genera of the family Rhizophoraceae have been constructed using the sequences of chloroplast genesmatK andrbcL as well as the ITS regions of nuclear ribosomal DNA. Relative-rate tests between lineages in these phylogenetic trees have been performed. On the basis of the results of the relative-rate tests and related molecular evolutionary rate data, the divergence times between the lineages are estimated as follows: (i) the first divergence time in these genera is 132.25 million years ago (mya); (ii) the average divergence time between two tribes, i.e. inland Legnotideae (exceptCarallia brachiata) and mangrove Rhizophoreae, is 64.13 mya; and (iii) the average divergence time between two inland species,C. garciniaefolia andC. pectinifolia, is 19.92 mya.     

一类散度型椭圆方程很弱解梯度的零点

考虑一类具有可测系数的散度型椭圆方程divG(x)u(x)=0.利用Hodge分解证明了其很弱解的梯度满足弱逆H(¨o)lder不等式,并得到了在其可积指数充分接近于2时,其很弱解梯度的几乎所有零点是无限阶的.     

Bio-sketches and partitioning of sympatric reed frogs,genus Hyperolius (Amphibia; Hyperoliidae), in two humid tropical African forest regions

Sympatric reed frog species were studied in Gabon (Monts Cristal: Hyperolius mosaicus, H. pardalis, H. tuberculatus) and Kenya (Kakamega Forest: Hyperolius acuticeps, H. cf. cinnamomeoventris, H. kivuensis, H. lateralis, H. viridiflavus). For each taxon, a standardized diagnosis covering 11 aspects of adult and in part tadpole morphology as well as the sequence of a 560 bp fragment of mitochondrial DNA of the 16S ribosomal gene are provided. In addition, behavioural data are given for each species including measurable parameters of advertisement calls. The Monts Cristal Hyperolius species clearly differ in their spatial arrangement through the choice of breeding site. Hyperolius species at the Kakamega Forest share the same breeding sites but in part differ in their activity pattern throughout the year. Advertisement calls of sympatric species in both regions mainly differ in temporal parameters.     

煤层气田地面集输系统的气井生产状态自动判识

针对"多点接入、柔性集输"工艺在气井计量与管理方面仍存在效率低且数据不准确的问题,提出一套基于时序数据的气井生产状态判识方法.首先采用自适应AR滤波方法来自动提取阀组倒井时间,然后基于JSD方法对各个时间段的气井生产状态进行判识,获得气井产气状态和设备运行状态.试验结果表明:该方法能够在复杂生产状态下准确判断出阀组的倒井时间和生产状态,有效减少了野外人工排采工作量,提高了生产管理效率.