Multiple Species Boreal Forests – What Faustmann Missed

Recent research in natural sciences shows that the dynamics in boreal forests are much more complex than what many models traditionally used in forestry economics reflect. This essay analyzes some challenges of accounting for such complexity. It shows that the optimal harvesting strategy for forest owners is history dependent and for some states of the forest, more than one strategy may be optimal.This paper confirms earlier literature on shallow lakes and coral reefs and shows that this kind of phenomena seem much more common than previously thought. They are valid for a wide range of ecosystems that cover large surfaces and they do not depend on the choice of some specific function to model the non-linearity. There are also indications that theses results could be obtained even for resources with concave growth if at least one species with non-linear growth affects their dynamics.     

Asymmetric effects of industrial production,money supply and exchange rate changes on stock returns in Turkey

The aim of this article is twofold: First, it examines the asymmetric effects of industrial production, money supply and RER on stock returns in Turkey by using the non-linear autoregressive distributed lag (NARDL) model over the periods of 1994:01–2017:05 and 2002:01–2017:05. Second, it tries to determine whether there is a change of these macroeconomic variables’ effects on stock returns after the 2001 financial crisis since after 2002 period represents a structural break from the past in terms of economic, political and macroeconomic policy approaches. The study finds that the effects of the changes in industrial production, money supply and RER on stock returns are asymmetric, and the asymmetries are larger after the 2002 subsample compared to the full sample period. The empirical results further suggest that tight monetary policies appear to retard the stock returns more than easy monetary policies that stimulate them.     

基于非线性效应的第三方支付平台兼容性研究

本文在设定网络外部性效用为符合梅特卡夫法则的非线性函数条件下,构建双寡头支付平台兼容和不兼容两种情况下的优化模型,探讨双寡头支付平台的兼容性策略选择问题。研究发现,规模对称的双寡头支付平台兼容之后,两家支付平台的利润、消费者效用及社会福利均会增加;银联成立后中国工商银行的银行卡业务利润得以提升也验证了模型结果。建议政府借鉴银联的成功经验,使银联在线成为各支付平台的聚合型平台,提高第三方支付清算系统的效率。     

商业聚集效应的动力学分析

商业聚集促进了区域商业经济的持续增长,提升了商业企业的经济效益。聚集到底给企业带来了多大的经济效应?企业之间应该如何协调发展?通过非线性动力学建模、分析,解决了这两个实际问题,为商业企业决策提供理论参考。     

基于稀疏分解和混沌理论的微弱信号检测

针对数字锁定放大器中稀疏分解算法检测精度受限的缺点,结合非线性方法进行补偿,采用混沌检测联合稀疏分解的算法设计了数字锁定放大器。数字锁定放大器借助稀疏分解算法估计信号参数,根据估计得到的参数设计对应混沌系统;利用混沌系统检测信号的过程中产生间歇性混沌状态,并通过测量间歇性混沌状态的周期,精确检测信号。最终,在信号的信噪比低至-20 dB时可以成功检测信号,频率精度达到0.05 Hz,提供了一种非线性微弱信号检测方法。     

Ishikawa迭代的非线性算子不动点逼近

本文在一致光滑的 Banach 空间,运用 Ishikawa 迭代,给出了方程解的逼近,进而将 C.E.Chidume 所研究结果从 Lipschitz 条件降至一致连续。关键词:巴拿赫空间;非线性算子;Ishikawa 迭代;强增生算子;强伪压缩算子;一致连续     

基于遗传算法的模糊控制器参数优化

针对非线性量化因子模糊控制器的参数对系统性能影响和参数间的相互制约,提出了一种基于遗传算法的参数整定与优化方法,并进行了仿真研究。仿真结果表明通过该方法寻优的系统具有更好的响应速度和控制精度；当对象结构或参数发生变化时,非线性量化因子模糊控制器可以重新整定参数,以保持良好的控制效果,具有很强的鲁棒性。     

Performance of Garch Models in Forecasting the Volatility of Exchange Rate for Developing Countries

This paper empirically investigates the performance of GARCH model in forecasting the volatility of exchange rate of some developing countries. We apply linear GARCH model and non-linear GARCH model. We fit these two models to some developing countries exchange rate index from January, 1998 to February, 2005. The return series of the developing countries＇ foreign exchange rate are leptokurtic, significantly skew, deviating from normality and volatile clustering as well. We find within-sample and out-of-sample evidence that conditional estimates of non-linear GARCH model outperform the conditional estimations of linear GARCH models. In our comparisons in most of the developing countries, the non-linear GARCH model produce better results than the linear GARCH model tor forecasting the volatility of exchange rate.     

Using Genetic Algorithms to Estimate and Validate Bioeconomic Models: The Case of the Ibero-atlantic Sardine Fishery

Synopsis The Neo-classical approach to fisheries management is based on designing and applying bioeconomic models. Traditionally, the basic bioeconomic models have used pre-established non-linear functional forms (logistic, Cobb–Douglas) in order to try to reflect the dynamics of the renewable resources under study. This assumption might cause misspecification problems and, in consequence, a loss of predictive ability. In this work we intend to verify if there is a bias motivated by employing the said non-linear parametric perspective. For this purpose, we employ a novel non-linear and non-parametric prediction method, called Genetic Algorithms, and we compare its results with those obtained from the traditional methods.