PIMD上一元多项式环的素理想分类

设R是主理想整环,若R有无穷多个极大理想,则称R是Principal Ideal Maximal Domain,简称为PIMD.设x是PIMD上的未定元,R[x]是R上的一元多项式环.依据整环的基本理论和唯一分解环的结构理论,研究R[x]的素理想和极大理想,推证了R[x]的任一主理想都不是极大理想,给出了构造R[x]的极大理想的一种方法,得到了R[x]的素理想是极大理想的条件,最终给出R[x]的素理想分类定理.     

Capybaras (Rodentia: Cavidae) in highlands: environmental variables related to distribution,and herbivory effects on a common plant species

The capybara Hydrochoerus hydrochaeris is one of the largest and most widely distributed herbivores in the Neotropical lowlands. However, as yet, there are no records of its occurrence in highland environments. Our aim was to evaluate the environmental variables related to the capybara’s distribution and monitor the effects of its herbivory on the individuals and on the reproductive phenology of A. polyanthus, a common and important plant species of the high-altitude grasslands. Our results show that capybaras frequently occur in the high-altitude grasslands along the Campo Belo River, but they avoid waterlogged areas, occurring more frequently on the dry rocky areas. Capybara herbivory affected the number of A. polyanthus rosettes in flower, leading to the presence of inflorescence formation anomalies. High-altitude grasslands apparently provide capybaras with the three main components (food, shelter and water) required for their occurrence. However, although they seem to present a seasonal feeding strategy, which also happens in lowlands, their avoidance of the waterlogged areas suggests that in highlands the species may present different environmental preferences from those presented in lowlands. In addition, the impact of capybaras’ herbivory on A. polyanthus individuals indicates the potential impact that capybaras can represent on the plant community of the high-altitude grasslands. This appears to be a great opportunity to study the effect of the arrival of a large herbivore in a new environment and possible impacts on plant assemblages.     

Redescription of Retilaskeya horrida (di Monterosato, 1874) comb. nov. and a re-evaluation of the taxonomic affinity of the genus Retilaskeya (Caenogastropoda: Triphoroidea)

The family Cerithiopsidae H. Adams and A. Adams, 1853 is distributed worldwide, and comprises around 800 extant species divided into ~40 genera. The most speciose genus within the family is Cerithiopsis Forbes and Hanley, 1850, a taxon currently used as a general receptacle rather than as a proper phylogenetic lineage. We hereby redescribe the rare species Cerithiopsis horrida di Monterosato, 1874, review its nomenclature, known material, and distribution as well as figure the entire protoconch, operculum, and radula for the first time. Our results highlight extreme differences between ‘Cerithiopsis’ horrida and the Cerithiopsis type species Cerithiopsis tubercularis (Montagu, 1803) and strong morphological and radular similarities with species belonging to the genus Retilaskeya Marshall, 1978. A wide discussion lists several taxa that might be ascribed to the same group of species, which presumably constitute a different worldwide lineage. Pending relevant molecular phylogenetic studies of the Triphoroidea Gray, 1847, for morphological conformity we suggest transferring ‘Cerithiopsis’ horrida to the genus Retilaskeya, and the same action is presumably appropriate for its possible sister species ‘Cerithiopsis’ leopardus Rolán and Gori, 2013. Finally, Retilaskeya better conforms to Newtoniellidae Korobkov, 1955 than Cerithiopsidae.     

基于领域本体的概念相似度算法研究

随着本体技术的逐渐成熟,如何为本体搭建语义桥梁以实现知识的重用与共享成为新的研究热点。在分析现有相关技术的基础上,提出一种计算不同本体中概念间语义相似度的方法,该方法以基于距离的概念相似度算法为基础,同时对概念结构进行分析将两者结合,从而计算出最终的概念间语义相似度。实验证明该方法有效。该研究工作可以应用于面向Web的知识检索领域。     

改进的波数域算法处理带有运动误差的机载SAR数据

机载SAR的一个关键问题就是准确的运动补偿.如果载机满足理想的匀速直线运动,传统的波数域算法是一种理想的成像算法,尤其在处理高斜视角和大孔径的SAR数据时,但它在处理带有运动误差的机载SAR数据时有一定的局限性,研究了改进的波数域算法,使之能与两步运动补偿技术结合,从而极大地扩展了波数域算法的应用范围.给出了仿真与原始数据成像结果.     

外加电场作用下层状铁电多晶材料板的模拟

建立了一个模拟在外加电场作用下的层状铁电多晶板的模型．该模型认为铁电材料的能量密度函数是变形和电位移的非凸函数以及引入了畴变对材料行为的影响．为了满足各晶粒间的运动学约束及电位移场的连续性条件,模型认为每个晶粒具有某种混合构形．通过常应力和常电场强度假设及利用加载过程中须满足的连续性条件,该模型将求解板对外加电场的响应问题转化为求解各晶粒中的应力及各晶界上的电位势的代数方程组的问题．同时,该模型利用两电畴的Ｇｉｂｂｓ自由能之差作为畴变的方向的判据,由要求板的Ｇｉｂｂｓ函数最小来确定畴变量的大小．     

守恒双曲型方程式激波计算区域分解法中的追踪及人工压缩方法

讨论在激波计算中的区域分解法,即在不同区域中应用不同网格及格式的耦合稳定性问题．先定出激波位置,再在激波附近小范围内,用低阶格式及人工压缩方法以消除弥散效应．在激波区域外,应用高精度格式,减少了过超振荡现象,提高了分辨率．在各区域交界应用全能稳定联接格式,解决了格式的耦合稳定问题．最后举出数值计算实例,计算结果与理论分析符合     

西南大西洋公海阿根廷滑柔鱼产量时空分布的初步研究

根据舟山新吉利远洋渔业有限公司2艘探捕船2007年与2008年的探捕资料,结合表温数据,对西南大西洋公海阿根廷滑柔鱼产量的时空分布进行了研究。结果表明,西南大西洋公海阿根廷滑柔鱼的渔期为1～6月,其中3～5月为高产期。渔场主要在45°～47°S、60°～61°W海域。产量重心位置总体呈较强的季节性分布,即两年的1～3月为一类,而4～6月另成一类。渔场表温升高是2008年产量重心南移的主要因素之一。     

Core loss analysis of Finemet type nanocrystalline alloy ribbon with different thickness

Nanocrystalline soft magnetic materials are widely used in power electronic applications due to their high permeability,magnetization and low core loss.In this paper,Fe_(73.5)Cu_1Nb_3Si_(15.5)B_7(at%)nanocrystalline alloy ribbons,with ultra-thin thickness of 14μm,and also 18 and 22μm,were prepared by a planar flow casting method with a single roller device.Soft magnetic properties of these ribbons were analyzed after nanocrystallization annealing.The experiments were conducted on toroidal samples using IWATSU B-H Analyzer over a frequency range of 10–100 kHz,at induction amplitudes of 100–500 m T,at room temperature.It was found that the excess eddy current loss P_(ex)was the dominant factor in the overall core loss above 10 k Hz.The toroidal samples made of the 14μm thickness ribbon exhibit very low total core loss of 48 W/kg at a frequency of100 kHz and magnetic flux density of 300 mT.The ratio of the P_(ex)was up to 89%at 100 kHz.The ribbon with lower thickness exhibits lower P_(ex)and therefore lower total core loss.The domain structure evidences were found.It indicates that the ribbons with small thickness are preferable for application in high frequency condition.     

高功率微波激励下p-n结器件响应

通过采用时域有限差分方法 (FDTD)和混合算法处理半导体器件所满足的刚性、耦合、非线性偏微分方程组 ,建立PN结半导体器件在高功率微波 (HightPowerMicrowave)激励下瞬态响应的一维模型 ,并在此基础上进行二极管功率耗散情况的分析和对微波信号响应截止频率的计算 ,从而对PN结半导体在高功率微波激励下的损伤机理进行研究 .计算表明 ,二极管功率耗散主要集中在源电压正半周峰值附近 ,器件的热击穿应发生在信号的正半周期内 ,10GHz应可视为该二极管对微波信号响应的截止频率