高新技术产业集群对创新型城市建设的影响研究

文章将高新技术产业集群和创新型城市建设联系起来,利用系统动力学理论和工具,构建因果回路图,对高新技术产业集群作用于创新型城市建设的机制进行分析,并探索两者之间的相互联系和作用模式,以期为创新型城市的建设提供一定的参考。     

供应链管理的快速反馈营销系统与4Ps营销系统仿真

企业如何快速响应市场是企业应对外界环境变化、赢得竞争优势的关键。文章从顾客需求出发,将供应链管理与市场营销相结合,运用系统动力学的理论与方法,研究传统4Ps营销系统与基于供应链管理的快速反馈营销系统两种营销模式的运营特点与绩效。并结合X企业的实际情况,运用Vensim.PLE仿真软件对两种营销模式进行仿真模拟,比较了两种模式的运营绩效。研究表明促使顾客满意度、订单率、销售量获得长期、快速增长的关键在于改变传统的营销系统模式,建立从顾客需求出发的基于供应链管理的快速反馈营销系统。     

Counter-Examples about Lower- and Upper-Bounded Population Growth

ABSTRACT

For a unimodal growth function f having its maximum at a critical state x _c , the interval bounding the population size asymptotically is usually presented as being equal to [f ^○2(x _c ), f(x _c )]. This interval however does not represent the maximum range within which the population size can vary, even asymptotically. The actual invariant interval containing the population size is equal to: [min(x*, f ^○2(x _c )), f(x _c )], where x* denotes the non-zero fixed point, assumed to be unique, of the iteration of f.     

A probabilistic transmission and population dynamic model to assess tuberculosis infection risk

The purpose of this study was to examine tuberculosis (TB) population dynamics and to assess potential infection risk in Taiwan. A well‐established mathematical model of TB transmission built on previous models was adopted to study the potential impact of TB transmission. A probabilistic risk model was also developed to estimate site‐specific risks of developing disease soon after recent primary infection, exogenous reinfection, or through endogenous reactivation (latently infected TB) among Taiwan regions. Here, we showed that the proportion of endogenous reactivation (53–67%) was larger than that of exogenous reinfection (32–47%). Our simulations showed that as epidemic reaches a steady state, age distribution of cases would finally shift toward older age groups dominated by latently infected TB cases as a result of endogenous reactivation. A comparison of age‐weighted TB incidence data with our model simulation output with 95% credible intervals revealed that the predictions were in an apparent agreement with observed data. The median value of overall basic reproduction number (R₀) in eastern Taiwan ranged from 1.65 to 1.72, whereas northern Taiwan had the lowest R₀ estimate of 1.50. We found that total TB incidences in eastern Taiwan had 25–27% probabilities of total proportion of infected population exceeding 90%, whereas there were 36–66% probabilities having exceeded 20% of total proportion of infected population attributed to latently infected TB. We suggested that our Taiwan‐based analysis can be extended to the context of developing countries, where TB remains a substantial cause of elderly morbidity and mortality.     

人口、消费、技术模式变化对我国海洋渔业生产影响的实证研究——以浙江舟山渔场为例

本文以舟山为例 ,在以往研究的基础上 ,修正了过去所建构的人口、消费、生产和资源的系统模拟分析框架 ,并利用系统动力学的方法 ,选择了投资规模、技术进步等变量进行了系统仿真模拟分析。研究结果表明 ,在渔业资源限定条件下 ,投资规模对渔业生产的影响是有限的 ;而技术进步的影响则是十分显著的 ;同时 ,劳动力资源短缺也将会显现出来     

Effects of parasitoid community structure upon the population dynamics of the honeysuckle leafminer,Chromatomyia suikazurae (Diptera: Agromyzidae)

Population dynamics of a leafminer,Chromatomyia suikazurae (Agromyzidae, Diptera) and its parasitoid community were studied for ten years at seven natural populations along an altitudinal gradient in Japan. This species which mines leaves of a forest shrub,Lonicera gracilipes (Caprifoliaceae), was attacked by 25 hymenopterous parasitoid species. Annually, the parasitoid community structure varied less within a population than among populations. The seven parasitoid communities were clustered into three groups corresponding to the altitudinal gradient: (a) lowland communities dominated by late-attacking, generalist pupal idiobiont eulophids and with highest species diversity, (b) hillside communities dominated by an early-attacking, specialist larval-pupal koinobiont braconid and (c) highland communities dominated by an early-attacking, generalist larval idiobiont eulophid. Annual changes of the host larval densities among the local populations were largely synchronous rather than cyclic. Among these populations, host density levels and mortality patterns greatly varied. By analyzing these inter-populational differences of host mortality patterns, the following conclusions were drawn: (1) The host mortality patterns were determined by the host utilization patterns of the locally dominant species. (2) The host pupal mortality but not larval mortality was related to species diversity but not to species richness itself of each parasitoid community. (3) Density dependence was detected only in pupal mortality at a lowland population dominated by late-attacking pupal parasitoids. These results suggest that interspecific interactions of parasitoids add additive effects to host population dynamics dissimilarly among local populations with different parasitoid communities.     

Stability of environment and of insect populations

Summary The abundance of moths was monitored with light-traps in two sites in southern Bohemia, České Budějovice for 22 years and in Černiš for 9 years. In these sites, that are vastly different in environmental stability and predictability, stability of insect populations was studied. The amplitude of fluctuations in abundance of the insect populations, as measured by the coefficient of variation (CV), varied a great deal between species so that there was a large overlap between the two sites. Nevertheless there was a highly significant tendency for species at Černiš, the more stable site, to have smaller values of CV, i.e., to be less fluctuating. Also in species co-occurring in the two sites, the CV at Černiš tended to be smaller. Trends in abundance of individual species over time, both increases and decreases, were common in both sites and did not differ between habitats. Environmental stability begets insect population stability in terms of the amplitude of the fluctuations, but trends in time occur irrespective of stability of the habitat.     

Dynamics of age- and size-structured populations in fluctuating environments: Applications of stochastic matrix models to natural populations

Recent developments of the theory of stochastic matrix modeling have made it possible to estimate general properties of age- and size-structured populations in fluctuating environments. However, applications of the theory to natural populations are still few. The empirical studies which have used stochastic matrix models are reviewed here to examine whether predictions made by the theory can be generally found in wild populations. The organisms studied include terrestrial grasses and herbs, a seaweed, a fish, a reptile, a deer and some marine invertebrates. In all the studies, the stochastic population growth rate (ln λ _s ) was no greater than the deterministic population growth rate determined using average vital rates, suggesting that the model based only on average vital rates may overestimate growth rates of populations in fluctuating environments. Factors affecting ln λ _s include the magnitude of variation in vital rates, probability distribution of random environments, fluctuation in different types of vital rates, covariances between vital rates, and autocorrelation between successive environments. However, comprehensive rules were hardly found through the comparisons of the empirical studies. Based on shortcomings of previous studies, I address some important subjects which should be examined in future studies.     

运营商与SP合作关系的系统动力学仿真研究

运营商与服务提供商（SP）的竞合关系一直是各方关注的重点问题,以移动增值业务产业链为研究对象,对SP和运营商的业务收入影响因素进行分析的同时,使用系统动力学进行仿真分析。通过对各影响因素调整,找到最优的合作模式,以实现整个产业链利润最大化。