基于自适应形态学的跳频信号参数联合盲估计

跳频通信的应用大大提高了军事装备的抗干扰和抗截获能力，使得跳频对抗技术面临严峻的挑战。为解决传统形态学跳频信号参数估计方法中结构元素选择困难问题并提高估计精度，提出了一种基于自适应形态学的跳频信号参数联合盲估计方法。首先，对跳频信号进行短时傅里叶变换获取谱图。然后，从其时间轴投影中获取结构元素尺寸的知识, 设计自适应形态学滤波器抑制谱图噪声, 提取跳频图案初步估计跳频参数。最后, 引入最小二乘估计方法, 对跳频周期和跳变时刻进行精估计。仿真结果表明，此方法能够同时估计出跳频频率、跳频周期和跳变时刻, 不需要其中某一种参数作为先验条件, 在复杂的通信环境也能够保持良好的估计性能。     

Molecular and morphological identification of two new African species of Dugesia (Platyhelminthes,Tricladida, Dugesiidae) from Cameroon

The paper describes two new Dugesia species collected from the rivers Messassi and Ntsetsensooh in Cameroon, representing the first planarian flatworms documented from this country. Based on morphological data, the new species Dugesia bijuga Harrath & Sluys, sp. nov. is characterized mainly by the presence of two diaphragms, a barrel-shaped penis that is traversed by numerous ducts of penis glands and is provided with a short nozzle, and the presence of two atrial folds. The other new species, Dugesia pustulata Harrath & Sluys, sp. nov., is characterized mainly by absence of a penis bulb, presence of a large, elongated and weakly muscular seminal vesicle, and by the ventroposterior section of the bursal canal being thrown into distinct folds. The phylogenetic position of the two new species was determined through a molecular phylogenetic tree, based on a mitochondrial and a nuclear gene, including species from the major geographical range of distribution of the genus Dugesia. The phylogenetic tree revealed that the Cameroon lineage does not constitute a monophyletic group with the other Afrotropical species; it also showed that the African continent may house a great diversity of Dugesia species that still remains to be discovered.

urn:lsid:zoobank.org:pub:007441A5-F037-4950-9F5B-AD6ED12A40ED     

小叶椴复合体的叶、花形态连续变异观察

紫椴(Tilia amurensis)和蒙椴(T.mongolica)是分布于北方的主要椴树属植物,形态上有差别但不易区分,二者均可称为小叶椴,本研究将其处理为"小叶椴复合体".利用形态扫描及便携式数码显微镜(Digital Portable Microscope)观察,对小叶椴复合体的叶、花形态指标进行测量,有助于深入了解其形态上的变异规律.研究结果显示,小叶椴复合体的叶、花形态存在连续性,特别是存在着雄蕊退化不完全的现象.     

Synopsis of ‘onychocellid’ cheilostome bryozoan genera

Genera assigned to the cheilostome bryozoan family Onychocellidae are revised based on the skeletal morphology of the type species and, when possible, the type material of these species. All genera are illustrated using scanning electron micrographs, some for the first time. Onychocellidae, which ranges from the Cenomanian stage of the Cretaceous to the Recent, has been a particularly troublesome family because of poorly defined generic concepts correlating at least in part with a paucity of morphological characters. Thirty-five genera are described in this review. Of these, two are recognised as subjective synonyms of other onychocellid genera (Rhebasia and Semieschara), one cannot be sufficiently characterised from the type material (Collura), and two are new: Aechmellina gen. nov. (type species Aechmella falcifera) and Kamilocella gen. nov. (type species Eschara latilabris). A neotype is chosen for Rhagasostoma hexagonum, the type species of Rhagasostoma. A key is provided to assist in the identification of onychocellid genera. Phylogenetic relationships between genera remain obscure and are unlikely to be fully resolved based on skeletal morphology alone. The family as an entity is loosely circumscribed and almost certainly paraphyletic, containing stem genera of other anascan familes such as Lunulitidae, Coscinopleuridae and Aspidostomatidae.

www.zoobank.org/urn:lsid:org:pub:63A31AD2-F049-42CB-A45B-557014DC286E     

800 MPa级耐酸管线钢高温热塑性研究

以一种800 MPa级耐酸管线钢铸坯为研究对象,采用Gleeble 3500试验机对其高温力学性能进行测试,运用金相显微镜、体视显微镜、扫描电镜及显微硬度计,对实验钢拉断后的微观组织、断口形貌及显微硬度进行表征。结果表明,在600～1000℃温度范围,实验钢种的断面收缩率均大于70%,表现出了较好的高温热塑性,但热塑性曲线在700～850℃之间出现了塑性低谷区,这与原始奥氏体晶界处先共析铁素体网膜的析出有关,故铸坯矫直温度选择应避开该温度区间。此外,实验钢还具有较好的高温强度,600℃下抗拉强度可达353 MPa。     

Nest structure and all stages of the long-cheeked yellow jacket Dolichovespula intermedia Birula (Hymenoptera: Vespidae)

Nest structure, morphology of all stages and behaviour have contributed to the phylogenetic and taxonomic studies of social vespids. Two aerial nests of Dolichovespula intermedia were discovered in China. The morphology of the three castes, the five larval instars, and the nest structure of D. intermedia Birula, are described in detail and illustrated. The presence of only one campaniform sensillum above each labial palp and the dense minute spicules on the posterior gena found in D. intermedia larvae are mentioned here for the first time for Dolichovespula. The identification characters between D. intermedia and Dolichovespula sylvestris are briefly discussed.