全球化、民族国家与东亚认同

近年来,“东亚共同体”问题已经成了东亚各国学术界不同领域热烈讨论的一个共同话题。不仅如此,东亚各国的商界和政界的精英也参加进来,以不同方式鼓动和推进“东亚共同体”的构建。东亚各国经济上相互依赖的加深固然给“东亚共同体”的构建提供了有利条件,但不可否认,对迅速发展变化的东亚地区前景的担忧,是许多人鼓吹“共同体”意识的另外一种重要推动力量。经过千百年的演进,东亚似乎正处于一个十字路口:是像现在欧洲国家一样,超越民族国家的界限,形成一种新的共同体?还是要重蹈欧洲国家的旧日覆辙,在融成共同体之前也来一番你死我活的较量?无疑,对东亚历史的再认识是我们思考这一问题的起点。目前东亚国家不仅生活在现实里,也徘徊在历史中。东亚国家间关系中时隐时现的矛盾和问题,无不与历史的纠葛纠缠在一起。人们不仅要问:我们构建“东亚共同体”的历史基础有多少?或者说历史能给“东亚共同体”的构建带来什么?正是为了解读这些问题,我们组织了这个专栏。应邀参加本专栏讨论的作者有在国际学术界声明显赫的“学界泰斗”,也有初出茅庐的青年学子。尽管他们的地位和视角不同,观点差异很大,但思考的主线都是“东亚共同体”的历史经验问题,每一篇文章都不乏予读者以启迪的真知灼见。我们相信这组文章?

A Homogeneous Linear Estimation Method for System Error in Data Assimilation

In this paper, a new bias estimation method is proposed and applied in a regional ensemble Kalman filter （EnKF） based on the Weather Research and Forecasting （WRF） Model. The method is based on a homogeneous linear bias model, and the model bias is estimated using statistics at each assimilation cycle, which is different from the state augmentation methods proposed in pre- vious literatures. The new method provides a good estimation for the model bias of some specific variables, such as sea level pres- sure （SLP）. A series of numerical experiments with EnKF are performed to examine the new method under a severe weather condi- tion. Results show the positive effect of the method on the forecasting of circulation pattern and meso-scale systems, and the reduc- tion of analysis errors. The background error covarianee structures of surface variables and the effects of model system bias on EnKF are also studied under the error covariance structures and a new concept ＇correlation scale＇ is introduced. However, the new method needs further evaluation with more cases of assimilation.

Impacts of Coffee Production in Agroforestry System for Sustainable Development

This study estimates the environmental and socioeconomic impacts of coffee production in the agroforestry system in the settlements of farmers located in the West of the state of Silo Paulo, Brazil, in the region known as Pontal of Paranapanema, aiming at the development of programs to support the growth of production sustainable coffee and programs to protect the coffee activity before the possible global climate change. The settlements are located in areas with sandy soils and highly degraded by human action Moreover, the region is considered marginal for the production of coffee, because it is subject to periods of high temperatures, prolonged drought and frost risk, which hinders the sustainability of farms. The environmental and socioeconomic impacts of agroforestry are analyzed through Ambitec-agro system, consisting of a set of indicators aimed at ex-post evaluation of the contribution of technological innovation to environmental, social and economic development of an agricultural activity. The system Ambitec involves： （1） general data collection about the technology; （2） application of questionnaires with adopters selected and insertion of data on impact indicators spreadsheets via platform MS-Excel and to obtain quantitative results and impacts partial indexes and aggregates the impact of technology selected; （3） analysis and interpretation of indices obtained, which vary between -15 and 15. The results indicate that agroforestry management can contribute to： （1） maintaining or increasing the sustainability of traditional coffee-growing regions in the case of sudden climate change; （2） the expansion of the coffee regions now considered unsuitable for the cultivation of coffee; （3） for sustainable regional development.

A formal structure for symbolic reachability analysis of rectangular hybrid systems

For symbolic reachability analysis of rectangular hybrid systems, the basic issue is finding a formal structure to represent and manipulate its infinite state spaces. Firstly, this structure must be closed to the reachability operation which means that reachable states from states expressed by this structure can be presented by it too. Secondly, the operation of finding reachable states with this structure should take as less computation as possible. To this end, a constraint system called rectangular zone is formalized, which is a conjunction of fixed amount of inequalities that compare fixed types of linear expressions with two variables to rational numbers. It is proved that the rectangular zone is closed to those reachability operations-intersection, elapsing of time and edge transition. Since the number of inequalities and the linear expression of each inequality is fixed in rectangular zones, so to obtain reachable rectangular zones, it just needs to change the rational numbers to which these linear expressions need to compare. To represent rectangular zones and unions of rectangular zones, a data structure called three dimensional constraint matrix(TDCM) and a BDD-like structure rectangular hybrid diagram(RHD) are introduced.

New minimal surfaces in the hyperbolic space

We obtain new complete minimal surfaces in the hyperbolic space H3, by using Ribaucour transformations. Starting with the family of spherical catenoids in H^3 found by Mori(1981), we obtain 2-and 3-parameter families of new minimal surfaces in the hyperbolic space, by solving a non trivial integro-differential system. Special choices of the parameters provide minimal surfaces whose parametrizations are defined on connected regions of R^2 minus a disjoint union of Jordan curves. Any connected region bounded by such a Jordan curve, generates a complete minimal surface, whose boundary at infinity of H^3 is a closed curve. The geometric properties of the surfaces regarding the ends, completeness and symmetries are discussed.