An agent-based simulation model of a primitive agricultural society

The paper describes a model of an agricultural society in which agents live in a single settlement and use the surrounding area to produce essential and non-essential goods. Agents make, and attempt to fulfil, consumption and production plans but markets do not always clear and goods can change hands at different prices between different pairs of agents. The model generates a wide range of agricultural landscapes, including those of a classical von Thünen economy. Demographically, it produces outcomes varying from logistic growth to periodic collapse caused by cyclical famines.     

海拉尔盆地查干诺尔凹陷下白垩统层序地层格架及沉积体系研究

依据岩芯、测井、录井和地震资料,以层序地层学理论为指导对海拉尔盆地查干诺尔凹陷下白垩统的扎赉诺尔群进行层序地层划分。扎赉诺尔群可划分为1个超层序,形成于凹陷断陷发育期,自下而上可划分为5个三级层序(Sq1、Sq2、Sq3、Sq4、Sq5)。进而在层序框架内对沉积体系类型和时空展布特征进行了分析。凹陷主要发育冲积扇、扇三角洲、湖底扇、滨浅湖和半深—深湖沉积体系,并且层序地层格架对各沉积体系分布具有控制作用。     

利津洼陷沙四上亚段滩坝沉积特征及控制因素分析

通过岩心观察、测井和地震资料分析,运用沉积学、层序地层学理论,将利津洼陷沙四上亚段分为1个层序3个体系域（LST、TST、HST）,并细分为7个准层序组。研究了滩坝砂岩的沉积特征和在准层序组内的平面展布,以准层序组1、2滨浅湖滩坝最发育,准层序组3、4风暴滩坝最发育,准层序组6、7砂质滩坝发育差但发育碳酸盐滩坝。对滩坝控制因素进行了探讨,首次提出了“气（气候）-源（物源）-盆（盆地）”系统控滩坝的分析思路,是对传统“源控论”的完善与补充,可更合理解释滩坝的成因和分布,增加预测性。     

The status of the passive treatment systems for acid mine drainage in South Korea

This study was performed to investigate the operating status, evaluate the problems, and discuss possible improvement methods of passive treatment systems for acid mine drainage (AMD) in South Korea. Thirty-five passive treatment systems in 29 mines have been constructed from 1996 to 2002 using successive alkalinity producing systems (SAPS) as the main treatment process. We investigated 29 systems (two for metal mines), 19 of which revealed various problems. Overflows of drainage from SAPS, wetland, or oxidation ponds were caused by the flow rate exceeding the capacities of the facilities or by the reduced permeability of the organic substance layer. Leakages occurred at various parts of the systems. In some cases, clogged and broken pipes at the mouths of the mine adits made the whole system unusable. Some systems showed very low efficiencies without apparent leakage or overflow. Even though the systems showed fairly good efficiencies in metal removal ratios (mainly iron) and pH control; sulfate removal rates were very poor except in three systems, which may indicate very poor sulfate reductions with sulfate reducing bacteria (SRB) as a means.     

Effects of in-situ conditions on relative permeability characteristics of CO2-brine systems

Carbon dioxide capture and geological storage (CCGS) is an emerging technology that is increasingly being considered for reducing greenhouse gas emissions to the atmosphere. Deep saline aquifers provide a very large capacity for CO₂ storage and, unlike hydrocarbon reservoirs and coal beds, are immediately accessible and are found in all sedimentary basins. Proper understanding of the displacement character of CO₂-brine systems at in-situ conditions is essential in ascertaining CO₂ injectivity, migration and trapping in the pore space as a residual gas or supercritical fluid, and in assessing the suitability and safety of prospective CO₂ storage sites. Because of lack of published data, the authors conducted a program of measuring the relative permeability and other displacement characteristics of CO₂-brine systems for sandstone, carbonate and shale formations in central Alberta in western Canada. The tested formations are representative of the in-situ characteristics of deep saline aquifers in compacted on-shore North American sedimentary basins. The results show that the capillary pressure, interfacial tension, relative permeability and other displacements characteristics of CO₂-brine systems depend on the in-situ conditions of pressure, temperature and water salinity, and on the pore size distribution of the sedimentary rock. This paper presents a synthesis and interpretation of the results.     

Rhodolith-bearing limestones as transgressive marker beds: fossil and modern examples from North Island, New Zealand

Rhodoliths are nodular structures composed mainly of the superimposed thalli of calcareous red algae. Because their development is controlled by an array of ecological parameters, rhodoliths are a valuable source of palaeoenvironmental information. However, despite their common use in palaeoecological reconstructions, the stratigraphic significance of rhodolith accumulations seldom has been addressed in detail. In a study of Cenozoic rhodolith‐bearing deposits from the North Island of New Zealand, rhodolithic units, usually of limited lateral extent, typically occur above major unconformities at the base of deepening upwards successions. Two types of transgressive rhodolith‐bearing deposits may be distinguished on the basis of texture and rhodolith internal structure: (i) type A deposits are clast‐supported rhodolithic rudstones containing abundant pebbles and cobbles reworked from the substrate, and are characterized by rhodoliths with a compact concentric to columnar internal structure and a high nucleus to algal cover ratio; (ii) type B deposits are rhodolithic floatstones with a matrix usually consisting of bryozoan fragments, benthic foraminifera and echinoid fragments or terrigenous silty fine sand. The rhodoliths of type B units usually have a loose internal framework with irregular to branched crusts. The two contrasting rhodolith‐bearing units are interpreted as characteristic facies of transgressive systems tract deposits, analogous to shell concentrations formed under conditions of low net sedimentation. Type A deposits are correlated with relatively high‐energy settings and/or narrow submerged palaeotopographic lows, whereas type B deposits are interpreted as forming in lower‐energy settings. The association between transgression and development of rhodolithic facies is confirmed by observations of a modern rhodolith production site at Whangaparaoa Peninsula in North Island, where algal nodules grow above a ravinement surface cut during the Holocene sea‐level rise, and also by a review of published fossil examples, many of which show stratigraphic and compositional attributes analogous to those of the New Zealand occurrences. The review indicates that transgressive rhodolith accumulations develop more commonly in, but are not restricted to, non‐tropical settings. It is suggested that a combination of factors, such as low net sedimentary input, nature of the substrate, sea‐level rise and inherited physiography contribute to determine the relationship between rhodolith‐bearing deposits and transgressive settings.     

奇异Itô随机系统几个重要基础问题的研究进展

近年来,一类由Itô随机微分方程驱动的奇异随机系统因其在实际领域中的广泛应用而备受关注.然而,系统方程同时包含奇异矩阵和扩散矩阵,大大增加了分析问题的复杂性.本文首先概述了奇异Itô随机系统几个重要基础问题的研究进展,主要包括:系统方程解的存在条件、广义Itô公式、容许性定义及稳定性问题.同时针对不同文献对上述问题的研究结果提出了自己的观点.最后对以上基础问题研究待解决的问题进行了展望.     

随机镇定与反镇定概述

本文概述了随机镇定与反镇定理论的研究现状.主要回顾了一个微分方程的随机镇定与反镇定普遍理论及其发展,并围绕该理论的应用和扩展从四个方面阐述连续时间系统噪声镇定理论的当前发展概况.此外,本文还概述了离散时间系统随机镇定方面的最新进展.     

随机非完整系统控制问题综述和展望

随着随机非线性控制的发展,随机非完整系统的控制引起了学者们的注意.本文首先探讨了随机非完整控制系统的镇定问题,涉及严反馈链式系统的反馈镇定和不满足严反馈的移动机器人镇定等;其次,介绍了该系统跟踪控制及现状;最后,在总结现有结果的基础上,分析了随机非完整系统发展的趋势,给出了6个可能的研究方向.     

Environmental Policies Can Buttress Conservation Norms

In an attempt to solve large-scale environmental problems, government agencies often resort to formal sanctioning systems: market-based incentives or command-and-control regulations, to promote cooperation. The purpose of this study was to investigate how the presence of these formal sanctioning systems impacts informal sanctioning systems for environmental protection. Study 1 used an experimental game to explore the influence of market-based and regulatory programs on informal sanctioning in a laboratory setting. Study 2 was a quasi-experimental field survey that compared informal sanctioning among Massachusetts residents living in towns with voluntary, mandatory, and pay-as-you-throw recycling programs. Results showed that in the presence of a formal sanctioning system, individuals felt guiltier for not engaging in the cooperative behavior and expressed more disapproval for non-cooperators. Combined, these results show that environmental policies can buttress conservation norms.