Analyses of spatial patterns and population processes of clonal plants

The nonrandom spatial structure of terrestrial plants is formed by ecological interactions and reproduction with a limited dispersal range, and in turn this may strongly affect population dynamics and population genetics. The traditional method of modelling in population ecology is either to neglect spatial pattern (e.g. in transition matrix models) or to do straightforward computer simulation. We review here three analytical mothods to deal with plant populations in a lattice-structured habitat, which propagate both by seeds that scatter over the whole habitat and by vegetative reproduction (producing runners, rhizomes, etc.) to neighboring vacant sites. [1]Dynamics of global and local densities: Dynamical equations of population density considering nearest-neighbor correlation (spatial clumping) are developed as the joint dynamics of global average density and local density (comparable to mean crowding) based onpair approximation. If there is a linear trade-off between seed production and vegetative reproduction, the equilibrium abundance of the population may be maximized by engaging both means of reproduction. This result is accurately predicted by the pair approximation method, but not by mean-field approximation (neglect of spatial structure). [2]Cluster size distributions: Using global and local densities obtained by pair approximation, we predicted cluster size distribution, i.e. the number of clusters of occupied sites of various sizes. [3]Clonal identity probability decreasing with distance: Multi-locus measurement of allozymes or other neutral molecular markers tells us whether or not a given pair of individuals belong to the same clone. From the pattern of clonal identity probability decreasing with the distance between ramets, we can estimate the relative importance of two modes of reproduction: vegetative propagation and sexual seed production.     

Σ型三能级原子与两个独立的单模电磁场相互作用动力学

本文利用时间演化因子的方法,给出了一个单模电磁场初态为相干态,而另一个单模电磁场初态分别为压缩相干态、偶相干态、奇相干态时,场—原子相互作用对原子粒子布居几率随时间演化规律的影响.     

Confidence bands for Brownian motion and applications to Monte Carlo simulation

Minimal area regions are constructed for Brownian paths and perturbed Brownian paths. While the theoretical optimal region cannot be obtained in closed form, we provide practical confidence regions based on numerical approximations and local time arguments. These regions are used to provide informal convergence assessments for both Monte Carlo and Markov Chain Monte Carlo experiments, via the Brownian asymptotic approximation of cumulative sums.     

高速自适应干扰抑制系统及实现技术研究

针对码率较高、实时性强的扩频抗干扰接力通信系统的窄带干扰抑制问题，提出了一种基于ＤＳＰ器件并行实现的自适应干扰抑制滤波器的设计。该系统是针对ＤＳＰ器件的特点，采用ＴＭＳ３２０Ｃ３０数字信号处理器及ＩＭＳＡ１１０专用滤波器并行处理的设计方法，实现了最高数据吞吐率为２０Ｍｂｐｓ的自适应滤波器，从而为高速实时自适应干扰抑制滤波器的实现提供了一种有效的途径。     

大功率多电子注TWT的大信号互作用分析与计算

多电子注技术是提高行波管功率水平的一种有效方法，其慢波结构为紧密耦合的螺旋线、梯形线或耦合腔阵列。文中将对以耦合腔阵列作为慢波结构的多电子注行波管进行分析，建立大信号分析的物理和数学模型，编制大信号计算程序，给定输入功率，计算得到了多电子注行波管的饱和功率、增益和电子效率。     

基于产品卖方市场的劳工标准移植研究

市场竞争促使越来越多发展中国家企业成为劳工认证供应链的一部分。劳工标准借助于贸易平台移植到中国,对中国劳工条件甚至劳工法律制度都产生一定影响,但对现实情况的分析发现其影响还处于初级阶段。基于产品卖方主导型市场结构,采用信号模型研究中国劳工标准移植的微观机理时发现,供应商的劳工标准趋于最低要求水平是供应商借助卖方市场势力帕累托改进的结果;当公司类型的概率分布函数为凹函数时,劳工标准会收敛到最低点均衡,而非高于最低点。发展中国家处于卖方主导型市场的企业要利用劳工标准移植契机,内在提高劳工条件,让劳工信号带动产品质量提高,为更多采购商和消费者接受,以获得更大的市场势力。     

On the Relationship between the Public’s Worry about Safety from Burglary and Probabilities of Burglary: Some Evidence from Simultaneous Equation Models

The increase in burglary crimes, along with the rise in the citizens’ worry about burglary crimes, has brought new challenges to the criminal justice systems in developed nations over the last decade. Crime surveys often point to a substantial dissonance between the actual likelihood of burglary and the perceived likelihood of victimization. This paper utilized data from the British Crime Survey to examine the relationship between (actual and perceived) probabilities of burglary and respondents’ worries about burglary by means of a system of two-stage least squares models. The empirical results show a strong relationship exists between households’ worries about burglary and their actual likelihood of being victimized by burglars in England and Wales. These findings suggest that households’ worries about burglary may not, afterwards, be misplaced.     

一种自适应跳频中的干扰检测算法

为提高跳频通信系统的可靠性和稳定性,根据线性数字调制信号的特点,对信号进行非线性变换,应用变换后信号的功率谱密度中所包含的信号特征信息,提出了一种适合于自适应跳频的干扰检测算法。该算法基于贝叶斯决策理论,属于盲信干(信噪)比检测。仿真结果表明,该算法满足跳频通信系统的要求。     

CO2气体保护焊电量信号的采集与分析

在PC机上利用Visual C＋＋ 6．0开发了CO2气体保护焊焊接过程电量信号采集系统．利用多线程技术与双缓冲区技术解决了高速数据采集时丢失数据的问题．分析结果表明：所开发系统能精确完整地采集到焊接过程中的电量信号．而且通过电流电压概率密度分布与熔滴过渡短路时间频数分布能直观地分析焊接过程的稳定性．为进一步研究焊接过程质量监测奠定基础．     

Is Context-Based Choice due to Context-Dependent Preferences?

The rationalization of context-based choice is usually based on the assumption that preferences are context-dependent. In this paper, we show that context-based choice can be due to the characteristics of the choice procedure applied by the individual and not to the dependence of preferences (stochastic or deterministic) on the context. Our arguments are illustrated focusing on the much-studied dominated-alternative effects.