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351.
In this paper, we propose a practical parallel algorithm for computinga b modc. The algorithm is based on RNS representatins of integers. In particular, a technique is introduced for avoiding overflow. The algorithm is easy to be implemented on hardware and achieves linear speedup. 相似文献
352.
353.
戴元熙 《东华大学学报(自然科学版)》1988,(3)
工业用槽边抽风的流场分布,目前尚缺乏完整的理论分析和理论与实验相结合的分析计算式。本文利用较简单的数学分析法,可以解决这方面的问题,所得的计算式便于理解和分析计算。 相似文献
354.
戴启润 《信阳师范学院学报(自然科学版)》1988,(1)
n—p散射是研究核力的重要实验,它间接地证明了核力与电荷无关。本文着重探讨极化态下n—p散射的四种情形,得出微分截面公式,计算自旋反转截面及几率。最后导出非极化态n—P散射的相关结论。 相似文献
355.
试论数学美及其教育价值 总被引:2,自引:0,他引:2
代钦 《内蒙古师范大学学报(自然科学版)》1992,(1):20-26
本文从数学美出发,阐述了数学美的对称性、统一性、简单性、奇异性、思维的经济性,客现实在性和民族文化传统的实在性。并对数学美感及其产生的4个主要原因,以及数学美的教育价值等问题进行了讨论。 相似文献
356.
提出一次对话中最大限度地获取决策偏好信息的有效途径并据此设计了新的多目标决策方法,可显著减少为找到最优决策进行对话的次数,数例仿真结果表明方法的有效性。 相似文献
357.
采用多元线性回归的方法,分别建立了平均车速、15%位车速、85%位车速与车道数、限速值、车道位置、车型、道路饱和度、大型车比例等6个因素之间的回归模型.然后,采用Logistic回归的方法,建立了车速选择的回归模型.分析结果表明:对于双向六车道普通公路,依据15%位车速,对超车道进行最低车速限制;依据85%位车速,对最高车速实施可变限速、分车道限速和分车型限速.外侧车道上的大型车在饱和度较高的情况下,容易选择低速行驶;双向两车道或四车道公路上的小型车在饱和度较低的情况下,容易选择高速行驶.根据车辆选择高速行驶的概率,设置不同的限速设施.利用这2个回归模型可以计算出特定道路条件下的15%位车速、85%位车速以及车辆选择高速行驶和低速行驶的概率,为普通公路在限速及限速设施选择方面提供依据. 相似文献
358.
Sun L Chen XJ Guo J Gao P Huang QZ Wang H Fang M Chen X Chen G Wu Q Zhang C Gu D Dong X Wang L Yang K Li A Dai X Mao HK Zhao Z 《Nature》2012,483(7387):67-69
Pressure has an essential role in the production and control of superconductivity in iron-based superconductors. Substitution of a large cation by a smaller rare-earth ion to simulate the pressure effect has raised the superconducting transition temperature T(c) to a record high of 55?K in these materials. In the same way as T(c) exhibits a bell-shaped curve of dependence on chemical doping, pressure-tuned T(c) typically drops monotonically after passing the optimal pressure. Here we report that in the superconducting iron chalcogenides, a second superconducting phase suddenly re-emerges above 11.5?GPa, after the T(c) drops from the first maximum of 32?K at 1?GPa. The T(c) of the re-emerging superconducting phase is considerably higher than the first maximum, reaching 48.0-48.7?K for Tl(0.6)Rb(0.4)Fe(1.67)Se(2), K(0.8)Fe(1.7)Se(2) and K(0.8)Fe(1.78)Se(2). 相似文献
359.
This study addressed three important aims:(1) undermining the previously obtained raw data about wood-decaying fungi(WDF) distribution and continuously investigating permanent plots to address certain scientific questions in ecology,(2) resolving the higher-level phylogeny of WDF with the help of multiple loci,and(3) testing and estimating the medicinal values of species that are closely related to well-known medicinal species.More than 1200 species and 2469 strains of WDF in China were identified from 28908 specimens collected from a series of field investigations.Using these materials,studies in multiple disciplines,such as ecology,taxonomy and phylogeny,and medicine,have been performed.With respect to ecology,the diversity of wood-decaying polypores significantly differed among a boreal forest zone,a temperate and warm temperate forest zone,and a tropical and subtropical forest zone.For instance,from north to south,the number and proportion of brown-rot species and the proportion of species found on fallen trunks were both decreased.The ecological patterns of wood-decaying polypores on gymnosperm and angiosperm trees were also explored by a case study in Northeast China.Although the total species richness was similar between the two tree groups,several other characteristics were significantly different,such as community structure and richness in certain substrates.The taxonomy and phylogeny of wide samples were referred to and their phylogenetic positions were resolved or at least partially established.In particular,phylogenetic knowledge about four genera,Fomitiporia,Ganoderma,Inonotus and Perenniporia,which include medicinal species,was essential for further research to determine the medicinal values of these types of fungi.Among these medicinal species,we mainly focused on Inonotus obliquus for its medicinal purposes.Polyphenols,polysaccharides and lanostane-type triterpenoids,extracted from the sterile conk of this species,could dramatically decrease levels of free radicals,DPPH and hydroxyl radicals,respectively.The metabolic profiles(both production and composition) of cultured I.obliquus mycelia could be altered by co-culture with other medicinal species or by induction of S-nitrosylation and denitrosylation,which may enhance the antioxidant capacity of I.obliquus. 相似文献
360.
实验研究了激光工艺参数(如激光平均功率、扫描速度、光斑直径等)对选区激光微烧结Cu基双组元混合金属粉末扫描线宽的影响及规律.结果表明:若激光平均功率越高、扫描速度越慢、光斑直径越大,则扫描线宽越宽;窄的扫描线宽需要低激光功率、快扫描速度、小光斑的工艺方案,其中小光斑对获得窄扫描线宽尤为重要.最后通过工艺参数的优化,获得了扫描线宽约为120μm的复杂三维金属零件. 相似文献