计算机网络安全中的防火墙技术研究

介绍一些经常性的网络安全问题,以及用一种相应的防御对策——网络防火墙,它技术的核心思想是在不安全的网络环境中构造一个相对安全的子网环境．讨论了实现防火墙的两种主要技术手段：一种是基于分组过滤技术（Packet filtering）,它的代表是在筛选路由器上实现的防火墙功能;一种是基于代理技术（Proxy）,它的代表是应用层网关上实现的防火墙功能．参5．     

非灭菌环境投加染料时间对白腐真菌降解活性染料的影响

应用氮限制液体培养基(C/N=56／8．7)研究了非灭菌环境投加染料时间对白腐真菌Phanerochaete chrysosporium降解活性艳红K-2BP染料的影响．试验结果表明,纯培养2d和3d后,在非灭菌环境投加活性艳红K-2BP染料的体系脱色率与在灭菌环境投加该染料的体系基本相当,其5d脱色率在90％以上;而纯培养ld时在非灭菌环境投加染料体系的脱色率却只有8l％．引起纯培养ld体系脱色率降低的主要原因是活性艳红K-2BP对白腐真菌Phanerochaete chrysosporium的生长有抑制作用和反应体系感染了酵母菌．但是,如果纯培养延长至2d以后,由于白腐真菌菌丝体已在体系内占优势,尽管在非灭菌环境下还有酵母菌侵入,但它不会占优势,从而也就不会影响白腐真菌对染料的降解作用．因此,在氮限制液体培养基中,只要白腐真菌Phanerochaete chrysosporium在反应体系占优势,就可以适当缩短纯培养时间,提前在非灭菌环境投加染料,使白腐真菌Phanerochaete chrysosporium的培养和对活性染料的脱色同步进行．     

Network structure and adaptive capacity in watershed governance

What supports the adaptive capacity of watershed governance? Using document review, interviews, and network diagrams, we analyze how structural attributes of a governance network emerged and co-evolved with changes in biophysical conditions in a case study of a small watershed in northeast Ohio. Results indicate that the network governance structure that emerged evolved to become a hybrid of two different structural forms that diversified stakeholder engagement, generated social capital, improved social learning, and stimulated change in management practices, all of which have enhanced adaptive capacity. A significant challenge to adaptive capacity arises, however, as network governance has come to rely significantly on a centralized organization to broker relationships for information and other resources.     

Integrated models to support multiobjective ecological restoration decisions

Many objectives motivate ecological restoration, including improving vegetation condition, increasing the range and abundance of threatened species, and improving species richness and diversity. Although models have been used to examine the outcomes of ecological restoration, few researchers have attempted to develop models to account for multiple, potentially competing objectives. We developed a combined state‐and‐transition, species‐distribution model to predict the effects of restoration actions on vegetation condition and extent, bird diversity, and the distribution of several bird species in southeastern Australian woodlands. The actions reflected several management objectives. We then validated the models against an independent data set and investigated how the best management decision might change when objectives were valued differently. We also used model results to identify effective restoration options for vegetation and bird species under a constrained budget. In the examples we evaluated, no one action (improving vegetation condition and extent, increasing bird diversity, or increasing the probability of occurrence for threatened species) provided the best outcome across all objectives. In agricultural lands, the optimal management actions for promoting the occurrence of the Brown Treecreeper (Climacteris picumnus), an iconic threatened species, resulted in little improvement in the extent of the vegetation and a high probability of decreased vegetation condition. This result highlights that the best management action in any situation depends on how much the different objectives are valued. In our example scenario, no management or weed control were most likely to be the best management options to satisfy multiple restoration objectives. Our approach to exploring trade‐offs in management outcomes through integrated modeling and structured decision‐support approaches has wide application for situations in which trade‐offs exist between competing conservation objectives.     

Exploring Environmentalism amidst the Clamor of Networks: A Social Network Analysis of Utah Environmental Organizations

Dwelling in a world awash in multiple environmental crises while science and social theory erode the last vestiges of the subject of humanism, it makes sense to imagine our world beyond the lens of humanism and turn to diverse methodologies in order to explore what is going on and how to promote changes that nurture ecological sustainability. In this essay we take on this task in relation to environmental communication. In what follows we explore the contours of the age after humanism, what we term the Age of the Animate Earth. In the wake of the theoretical and actual deconstruction of the subject, we offer networks as a key unit of analysis. From this perspective, we suggest social network analysis (SNA) as one viable method for doing environmental communication studies and perform this move through a SNA of Utah environmental groups.     

Using social network and stakeholder analysis to help evaluate infectious waste management: A step towards a holistic assessment

Assessing the strengths and weaknesses of a solid waste management scheme requires an accurate analysis and integration of several determining features. In addition to the technical aspects, any such system shows a complex interaction of actors with varying stakes, decision-making power and influence, as well as a favourable or disabling environment. When capitalizing on the knowledge and experience from a specific case, it is also crucial that experts do not “forget” or underestimate the importance of such social determinants and that they are familiar with the methods and tools to assess them. Social network analysis (SNA) and stakeholder analysis (SA) methods can be successfully applied to better understand actors’ role and actions, analyse driving forces and existing coordination among stakeholders, as well as identify bottlenecks in communication which affect daily operations or strategic planning for the future way forward. SNA and SA, appropriately adjusted for a certain system, can provide a useful integration to methods by assessing other aspects to ensure a comprehensive picture of the situation. This paper describes how to integrate SNA and SA in order to survey a solid waste management system. This paper presents the results of an analysis of On-Nuch infectious waste incinerator in Bangkok, Thailand. Stakeholders were interviewed and asked to prioritize characteristics and relationships which they consider particularly important for system development and success of the scheme. In such a way, a large quantity of information about organization, communication between stakeholders and their perception about operation, environmental and health impact, and potential alternatives for the system was collected in a systematic way. The survey results suggest that stakeholders are generally satisfied with the system operation, though communication should be improved. Moreover, stakeholders should be strategically more involved in system development planning, according to their characteristics, to prevent negative reactions.     

城镇化平原河网区下垫面特征变化及洪涝影响研究

城镇化是人类改变地表最深刻、最剧烈的过程之一,针对平原区城镇化引起的洪涝加剧问题,以浙东沿海奉化江流域中下游平原为例,利用高分辨率遥感影像和地形图资料获取1990~2010年间下垫面特征信息,从土地利用类型、河网水系和地面高程3个方面,分析城镇化过程中平原河网地区下垫面特征变化及其对区域洪涝调蓄能力的影响。研究结果表明:平原区城镇化对下垫面的影响不仅表现为城镇不透水面的增加,径流系数的增大,同时城镇扩张过程中农田和水系转化为城镇用地,而后者具有相对较高的防洪标准,使得新建城区地面高程明显增大,河网调蓄能力亦呈不断减少趋势。洪涝模拟显示以上下垫面变化导致区域可调蓄洪涝的空间逐渐减少,洪涝风险程度加大,并呈现向相对低洼地带转移的趋势特征。     

1985年以来江苏省土地利用变化对人类活动程度的响应

利用1985、1995、2005和2008年4期遥感影像解译获取的土地利用变化数据,从土地利用变化速度、转移方向和土地利用程度方面,借助GIS空间分析和图谱分析技术及Ucinet社会网络分析软件,全面定量分析江苏省1985年以来人类活动作用下土地利用时空变化规律。研究表明:(1)1985~1995、1995~2005、2005~2008年3个时段江苏省的土地利用综合动态分别为12.95%、17.17%、15.03%,反应了人类活动对江苏省土地利用变化的影响程度呈现出"缓慢影响—剧烈影响—影响减缓"的倒U型曲线规律;(2)1985年以来,耕地、建设用地和水域之间的空间转移是江苏省土地利用转移的关键,也是人类影响土地利用最主要的表现形式,3种地类的相互转移占所有土地转移流的80%以上,其中耕地转为建设用地所占比例最大,主要分布苏锡常及南京4市的市辖区,以及昆山、江阴等经济发达的县市及苏北的宿迁市、淮安市、徐州市;(3)1985年以来,追求净产出(利润)的增长是土地利用变化的内在动力,导致建设用地增加及耕地减少,使得全省土地利用程度整体水平不断升高;受可驱动的有效资本量控制,经济发达的苏南地区一直是人类活动影响土地利用最为剧烈的区域,而苏北地区随着经济实力的不断提升土地利用受人类活动影响的程度也在逐渐增强。     

汞矿区周边农田土壤微生物群落结构特征及其环境驱动因子

为探究汞矿区周边农田土壤微生物群落结构特征及其与环境驱动因子关系,以铜仁汞（Hg）矿区周边（碧江区坝黄镇、石阡县花桥镇、江口县凯德镇和碧江区川硐镇,分别用BJ、SQ、JK和TR表示）农田土壤为研究对象,分析了土壤理化性质、Hg污染状况、酶活性以及微生物群落结构特征.采用冗余分析（RDA）和相关性网络分析了土壤微生物群落结构与环境因子互作关系.结果表明,研究区土壤存在一定程度的Hg污染,其中,JK和TR属于轻度污染,SQ和BJ属于偏中度污染;TR存在中等潜在生态风险,BJ和JK存在强潜在生态风险,SQ存在很强潜在生态风险.研究区土壤的主要细菌优势菌群包括：变形菌门（Proteobacteria）、放线菌门（Actinobacteria）、酸杆菌门（Acidobacteria）和绿弯菌门（Chloroflexi）;主要真菌优势菌群包括：子囊菌门（Ascomycota）、担子菌门（Basidiomycota）和被孢霉门（Mortierellomycota）.RDA分析表明,pH、蔗糖酶（SC）和过氧化氢酶（CAT）活性是土壤细菌群落结构组成的主要环境因子,pH、碱解氮（AN）、速效钾（AK）、HCl-Hg、酸性磷酸酶（ACP）和脲酶（URE）活性是土壤真菌群落结构组成的主要环境因子.相关性网络分析表明,pH、AP、HCl-Hg、SC、ACP和CAT是影响土壤Proteobacteria、Acidobacteria、Actinobacteria、Chloroflexi、厚壁菌门（Firmicutes）、棒状杆菌门（Rokubacteria）和浮霉菌门（Planctomycetes）等细菌群落结构的主要环境因子;而AK、pH、TN、AP、AN、ACP、URE和SC活性是影响土壤Ascomycota、Basidiomycota、Mortierellomycota、球囊菌门（Glomeromycota）、壶菌门（Chytridiomycota）、红藻门（Rozellomycota）、梳霉门（Kickxellomycota）和Mucoromycota （毛霉门）等真菌群落结构的主要环境因子.     

苏州水环境自动预警监测网络体系发展思路研究

近年来,随着经济社会的发展,城市的工业化程度的不断提高,由此也带来的环境问题,特别是水环境污染形势相当严峻。苏州水环境自动监测网络经过10多年的发展,已形成了由69个自动监测点住组成的网络体系。但随着社会经济的高速发展、环境问题的日益复杂,目前的自动监测体系亟需进一步发展提升。文章深入探讨了苏州水环境自动监测网络体系目前存在的问题,在网络布局、监测能力、管理体系等方面提出改善设想,以期进一步完善自动预警监测体系结构。