A Note on Diophantine Equation Ax~4+ 1 = By~2 and Erds'''' Conjecture on Combinatorial Number

oINTRODUCT1ONLetNbethesetofpositiveintegers.LetA,BeNwithgcd(A,B)=l,B>landBissquarefree.Thereweremanypaperscon-cernedwiththeequationAx4+l=By',x,yeN(1)writtenbyLjunggren,Cohn,KeandSun,andtheauthoretc.(seell]).LjunggrenI']provedthatifA=land(l)hassolution(x,y),thenX2+yJB=n',(2)wheren=uo+v,Inisthefundamentalsolu-tionofPell'sequationu2-Bv2=-l,uo=dut,d,u,eN,dissquarefree.Infact,repeatingthemethodof[3]com-pletely,wecanproveTheoremlTheequation(l)hassolution(x,y)ifandonlyiftheequationAu2…     

一种改进的共轭梯度法及全局收敛性

在DY共轭梯度法的基础上对解决无约束最优化问题提出一种改进的共轭梯度法．该方法在标准wolfe线搜索下具有充分下降性，且算法全局收敛．数值结果表明了该算法的有效性．最后将算法用于SO2氧化反应动力学模型的非线性参数估计，获得满意效果．     

Drivers of Plant Invasion at Broad and Fine Scale in Short Temperate Streams

Riparian ecosystems have been described as highly prone to alien plant invasions; thus, disentangling the contributing factors of the invasion process is of utmost importance to conserving and managing these valuable ecosystems. In this study we examined the drivers of riparian plant invasion in 16 Cantabrian river basins (northern Spain) ranging from 100 to ca. 1050 km². A complete flora was determined for five randomly selected sites within those basins. One hundred and thirty alien plant species were found across the 80 sampling sites, representing 21% of the recorded total flora. At site scale, the level of plant invasion, measured as alien richness (AR) and relative alien richness (RAR), was assessed in relation to a set of explanatory variables by means of Generalised Linear Mixed Models. This level of invasion was influenced by environmental variables such as the thermicity index, the average riverbed width and the number of plant communities and by human‐related variables such as the distance to the nearest town and the proportion of surrounding urban land. At basin scale, industrialised river basins were more heavily invaded than non‐industrialised basins, and they both differed in their alien plant composition. Given that some of the alien species occurring in Cantabrian streams are specially abundant (Crocosmia x crocosmiiflora) and/or form very dense stands (Fallopia japonica, Paspalum distichum), future research should focus on the drivers that influence the presence and distribution of these species of special concern. Copyright © 2016 John Wiley & Sons, Ltd.     

VDR图像自适应压缩算法的研究*

针对船载航行数据记录仪（VDR）中对雷达图像压缩的要求,分析图像的灰度丰富度、平滑度特征,建立了图像灰度丰富度、压缩比和压缩质量的关系及平滑度、压缩比和压缩质量之间的数学模型。提出以图像的灰度丰富度指标来自适应选择ZIP压缩或JPEG压缩算法以便获得最优的基本算法,并提出以图像的灰度平滑度来自适应确定JPEG压缩算法的压缩质量参数以便获得恒定的压缩比,实现了VDR图像的自适应优化压缩。     

平面自治系统的有界性

研究一般平面自治系统的解的有界性．给出了两个有界性的充分条件和一个闭轨存在性的判据．     

论学分制导向下大学课程的丰富性

推行学分制是当前我国高校教学管理改革一项迫切而重要的措施。文章分析了学分制导向下大学课程的丰富性,进而提出学分制导向下丰富大学课程的几点看法。     

关于对数积分的基本理论

提出了实对数导数与对数积分的基本理论 ,证明了实对数导数和对数积分与 (常义 )导数和积分的关系及充要条件 ,所得到的定理与公式在实数域内对处理函数乘、除、乘方、开方及复合函数的性质具有独特的优势 .实对数导数与对数积分的基本理论是对经典微积分理论的扩充     

建筑展览的"厚度"(下)--论两次中国当代建筑展

在上篇对于1927年魏森霍夫住宅博览会回顾与审视的基础上,此篇述及两次当代中国建筑展, 论述了展览内容、过程、机制等因素对于它所能具有的“厚度”的影响,以及就建筑展览的批判性内涵而言,作为一种特殊建筑类型的社会住宅的价值。最后并反思了建筑领域内展览行为的当代意义及建筑师在此类展览中通常采取的姿态。     

一类奇异二阶边值问题正解存在的充分必要条件

本文利用锥拉伸与压缩不动点定理,在非线性项为超线性或次线性及非线性项可分解为超线性与次线性的情况下,给出一类二阶边值问题有一阶可导正解的充分必要条件,推广并改进了一些已知的结果。     

Performance Analysis of Distributed Neyman-Pearson Detection Systems

The performance of a distributed Neyman-Pearson detection system is considered with the decision rules of the sensors given and the decisions from different sensors being mutually independent conditioned on both hypothese. To achieve the better performance at the fusion center for a general detection system of n 〉 3 sensor configuration, the necessary and sufficient conditions are derived by comparing the probability of detec- tion at the fusion center with that of each of the sensors, with the constraint that the probability of false alarm at the fusion center is equal to that of the sensor. The conditions are related with the performances of the sensors and using the results we can predict the performance at the fusion center of a distributed detection system and can choose appropriate sensors to construct efficient distributed detection systems.