加权最小范数平差的伪观测解法

本文首先证明了加权最小范数平差一般解的一个重要特征，由此提出了利用附加虚拟观测方程来求解的方法；并且证明了该法与一般解法等价性的充要条件，最后讨论了伪观测方程构造原理。     

高等数学教学拾零

现行的一些高等数学教材对某些基本问题的论述说法不一，存在缺憾，不利于教学。本对此做了分析、比较与评述。     

关于完全分配格结构的两个定理

本文建立了“极小集理论”与Ｒａｎｅｙ的一个定理之间的内在联系；引进了正则并既约元的概念并用此概念给完备的完全分配格一个新的特征     

新型滚珠离合器结构设计

本文介绍一种结构简单、造价低廉、体积小、接合、分离迅速的新型滚珠离合器的结构设计原理．     

大围长图中控制圈的一个局部条件

设Ｇ是围长大于或等于５的连通图．本文证明了；如果对Ｇ中每个顶点ｖ，距离ｖ为２和３的顶点导出的子图的独立数不大于最小度的两倍减３，那么Ｇ中有控制圈．     

无约束极值条件的一个证法

无约束极值条件是最优化理论的重要组成部分，在理论上和实践上都有重要意义，约束问题的最优性条件是它的逻辑推广，解约束最优化问题的一种策略是解一系列无约束问题。本文首先介绍Ｒａｙｌｅｉｇｈ商定理，然后利用Ｒａｙｌｅｉｇｈ商定理给出无约束极值条件新的严格证明。这种方法比已有证法更简明，对那些不熟悉序列极限理论的读者，在学习和掌握最优化理论方面，有一定的实际意义。     

Population biology of figs: Applications for conservation

Summary The flowering phenology typical of at least monoecious figs-intra-tree synchrony and inter-tree asynchrony-poses problems for persistence of the pollinator population, and hence of the fig population itself, when fig population size is small. Establishment and maintenance of a population of the short-lived, species-specific wasp pollinator require that the fig population include a critical minimum number of trees (critical population size: CPS). Below CPS, temporal gaps between flowering trees occur that are unbridgeable by the pollinator, leading to its local extinction. This has implications for conservation in two contexts: human-aided invasions of introduced fig/wasp pairs, in which initial populations of figs and/or wasps may be small, and the persistence of figs and wasps in fragmented forest, in which initially large populations may be drastically reduced. Long-distance range extension by fig/wasp pairs is problematical for two reasons: 1) the fig species must first attain CPS, most likely through repeated seed dispersal events, before the wasp can establish; and 2) long-distance transit should be difficult for the tiny, short-lived wasp pollinators. I review the biology of natural and human-aided range extension by figs and fig wasps, and show that in human-aided range extensions these two difficult steps are circumvented. Once introduced into an area where hosts are abundant, fig wasps should readily establish from a small number of initial colonists, since they mate before dispersal and are highly tolerant of inbreeding. They are thus less subject than many insects to the genetic and demographic hazards of small population size. Of 5–6 fig/wasp pairs that have performed human-aided long-distance range extensions, one Asian pair,Ficus microcarpa and its pollinatorParapristina verticillata, is established in numerous areas in the northern neotropics, and the plant may become a serious weed. In tropical forests, figs may provide keystone resources for frugivores, providing fruit during seasons when other resources are scarce. Figs pose difficult problems for conservation biology, since minimum viable populations appear to be large, and since many species of tropical rainforests occur at low densities. This means that minimum areas required for persistence of a fig population- and for those of other species that would be affected were figs to be removed from the system-may often be large.     

球磨MgO·Ni2O3固溶体为负载纳米Ni催化剂前驱物催化热解法制备碳纳米纤维

以球磨技术(Ball Milling,BM)制得MgO@Ni2O3固溶体前驱物,并以直接还原法制得Ni/MgO纳米负载型催化剂,以催化热解法合成出管状的碳纳米纤维.     

最小费用的网络瓶颈分析

已有的瓶颈分析对于系统性能的评估和改进方案的设计选择难以奏效。针对这一问题,该文对最小费用网络进行了瓶颈分析。首先给出了严格的瓶颈定义,使得最小费用目标的变化成为瓶颈链路容量调整的映射,并给出基于最小费用网络最优化条件的瓶颈分析的原理和算法及瓶颈迁移和瓶颈裕度的定义和算法,最后通过案例分析说明了3类瓶颈的行为特征,表明它们能够对系统性能的评估和改进方案的设计选择提供支持。     

Schreiber approach for GPS carrier phase ambiguity resolution

Differenced GPS carrier phase observations are usually used in GPS positioning to eliminate the various common GPS errors. A different approach is proposed in this paper where no differencing of the observations is required. In this method, the common GPS errors are modelled explicitly and eliminated by introducing the Schreiber method, which is used in traditional geodesy to eliminate the azimuth unknowns in observation equations. The paper first introduces the Schreiber method, and then discusses its application to the various GPS common-mode error models. It is shown that if only the real ambiguity solution is concerned, the estimate of the position parameters from the Schreiber approach is the same as that from the differencing approach. However, the variance of the ambiguity estimate from the Schreiber approach is smaller than that from the differencing approach. Numerical examples are given to show that the results are reliable.