Windows环境下网络蠕虫仿真和预测算法

提出一种在Windows环境下对网络蠕虫传播程序进行仿真和预测的算法。该算法在假设的网络环境下,利用软件模拟蠕虫在网络中爆发后传播的过程,并记录传播时间内网络的状态,最后生成基于时间变化的网络状态曲线图。可定量预测网络蠕虫在既定环境下的传播趋势。分析结果表明:该算法的预测结果与数学建模结果极为接近,具有较强的实用价值。     

锅炉汽包水位保护误动的分析及防范措施

针对某发电厂1号锅炉汽包水位测量值突变,造成汽包水位高高保护信号误发,导致锅炉主燃料跳闸(Main Fuel Trip,MFT)动作的事件,结合发电厂分散控制系统(DistributedControl System,DCS)及现场一次设备具体情况,对事故原因进行分析,提出了改进措施。结果表明:引起汽包水位测量值突变的直接原因是现场存在干扰源。采取有效措施后,系统的抗干扰性能得到增强,控制系统恢复正常。     

中国城市空间分布的省际差异及其影响因子分析

采用全国县城所在的建制镇与所有设市城市数据,以省区作为基本研究单元,运用最近邻分析与种群分布理论定量分析了2009年城市体系空间分布的省际差异及其影响因素。研究表明:2009年我国各省区的城市空间分布格局以均匀分布为主,明显表现出集聚分布的仅有西藏、青海和新疆三省;通过对中国各省区城市分布与自然、社会经济条件进行回归分析发现,各省区城市的空间分布模式与自然及社会经济因素具有较强的相关性;从各变量的重要性来看,影响区域城市空间分布形态最主要的因素是路网密度,其次分别是复种指数、人均耕地面积、土地垦殖率与城市化率;城市在发展的过程中,为了获得足够的要素维持自身生长,各城市必定会最大化地攫取要素资源,导致了城市之间的资源竞争;区域内城市的外部环境越趋于均匀,城市的空间分布越趋于均匀,而区域内城市外部环境分布不均则导致城市表现出集聚分布模式;在其他影响因素不变的情况下,复种指数与城市化水平的提高在一定程度上降低了城市分布对其他因素的依赖。     

南京地区7Be沉降特征

7Be是研究大气科学与地球化学的核元素之一,对研究短期过程的地表土壤颗粒迁移具有较大价值。为了解南京地区利用7Be进行土壤侵蚀示踪研究的合适时机,于2010年1月~2011年12月收集南京地区各月的7Be沉降样品,经实验室化学实验处理和γ谱仪测量,计算7Be沉降通量,并分析7Be大气沉降的季节性变化趋势。结果表明：南京地区平均7Be沉降量为1 62178 Bq/（m2·a）,沉降通量为066～1449 Bq/（m2·d）,平均沉降通量为444 Bq/（m2·d）;7Be沉降通量的季节变化呈现双峰型趋势,冬末春初和夏季是两个高值区;7Be沉降的а值冬春季较大,夏季最低;降雨量大小与沉降量存在明显的正相关     

地质灾害防治绩效考核评价体系探讨

地质灾害防治纳入政府绩效考核是当前实践中迫切需要解决的重要课题。提出了地质灾害防治绩效考核的概念,并从目的、指标、主体、方法等4个方面建立了地质灾害防治绩效考核体系。应用所建立的绩效考核体系进行了实证分析,验证了考核体系的客观、实用和可靠性。研究成果为地质灾害防治科学管理提供了基础依据。     

Control strategies of atmospheric mercury emissions from coal-fired power plants in China

Atmospheric mercury (Hg) emission from coal is one of the primary sources of anthropogenic discharge and pollution. China is one of the few countries in the world whose coal consumption constitutes about 70% of total primary energy, and over half of coals are burned directly for electricity generation. Atmospheric emissions of Hg and its speciation from coal-fired power plants are of great concern owing to their negative impacts on regional human health and ecosystem risks, as well as long-distance transport. In this paper, recent trends of atmospheric Hg emissions and its species split from coal-fired power plants in China during the period of 2000-2007 are evaluated, by integrating each plant's coal consumption and emission factors, which are classified by different subcategories of boilers, particulate matter (PM) and sulfur dioxide (SO2) control devices. Our results show that the total Hg emissions from coal-fired power plants have begun to decrease from the peak value of 139.19 t in 2005 to 134.55 t in 2007, though coal consumption growing steadily from 1213.8 to 1532.4 Mt, which can be mainly attributed to the co-benefit Hg reduction by electrostatic precipitators/fabric filters (ESPs/FFs) and wet flue gas desulfurization (WFGD), especially the sharp growth in installation of WFGD both in the new and existing power plants since 2005. In the coming 12th five-year-plan, more and more plants will be mandated to install De-NO(x) (nitrogen oxides) systems (mainly selective catalytic reduction [SCR] and selective noncatalytic reduction [SNCR]) for minimizing NO(x) emission, thus the specific Hg emission rate per ton of coal will decline further owing to the much higher co-benefit removal efficiency by the combination of SCR + ESPs/FFs + WFGD systems. Consequently, SCR + ESPs/FFs + WFGD configuration will be the main path to abate Hg discharge from coal-fired power plants in China in the near future. However advanced specific Hg removal technologies are necessary for further reduction of elemental Hg discharge in the long-term.     

民用建筑生命周期固体废弃物排放的资源环境压力

降低民用建筑生命周期固体废弃物排放带来的资源环境压力,促进经济发展逐步走上资源减量化和环境减压化的轨道,是全社会面临的共同问题。本文借用生态足迹方法和能值分析方法,构建了民用建筑生命周期各阶段固体废弃物排放的资源环境压力计算模型,并以沈阳市图书馆为例,进行了实证研究。结果表明:废弃水泥排放引起的资源环境压力分别占施工阶段生态足迹的48.56%,占使用与维护阶段生态足迹的82.78%,占拆除及废弃建材处置阶段生态足迹的56.73%;而废弃商品混凝土排放造成的资源环境压力在施工阶段生态足迹和拆除及废弃建材处置阶段生态足迹中的比例分别为31.90%和37.26%;就生命周期各阶段而言,拆除及废弃建材处置阶段固体废弃物排放的资源占用足迹最大,占总足迹的92.91%,使用与维护阶段资源占用足迹最小,占总足迹的1.06%。因此,民用建筑在生命周期各阶段削减固体废弃物排放量的重点是减少水泥和商品混凝土的用量,多开发可替代混凝土结构的钢结构或组合结构形式的民用建筑。     

基于CGE模型的极端冰雪灾害经济损失评估

结合极端冰雪灾害的特点及传导途径,构建了极端冰雪灾害经济损失综合评估的总体框架,并以湖南省可计算一般均衡模型(HNUGE)为基础,通过在传统模块的基础上增加农业损失传导模块、电力业损失传导模块和交通业损失传导模块等三项冰雪灾害传导模块,实现了对传统HNUGE的拓展和改进,构建了更具针对性的极端冰雪灾害经济损失综合评估的可计算一般均衡模型。该模型能够更科学地估计极端冰雪灾害造成的综合损失,通过对2008年湖南冰雪灾害进行实证分析,发现模型运算结果与实际情况基本一致,验证了该模型的实用性和可行性。     

Biodegradation of Chlorimuron-ethyl by the Bacterium Klebsiella jilinsis 2N3

Enrichment culturing of sludge taken from an industrial wastewater treatment pond led to the identification of a bacterium (Klebsiella jilinsis H. Zhang) that degrades chlorimuron-ethyl with high efficiency. Klebsiella jilinsis strain 2N3 grows with chlorimuron-ethyl as the sole nitrogen source at the optimal temperature range of 30–35°C and pH values between 6.0–7.0. In liquid medium, the degradation activity was further induced by chlorimuron-ethyl. Degradation rates followed the pesticide degradation kinetic equation at concentrations between 20 and 200 mg L^?1. Using initial concentrations of 20 and 100 mg L^?1, the degradation rates of chlorimuron-ethyl were 83.5 % and 92.5 % in 12 hours, respectively. At an initial concentration higher than 200 mg L^?1, the degradation rate decreased slightly as the concentration increased. The 2N3 strain also degraded the sulfonylurea herbicides ethametsulfuron, metsulfuron-methyl, nicosulfuron, rimsulfuron, and tribenuron-methyl. This study provides scientific evidence and support for the application of K. jilinsis in bioremediation to reduce environmental pollution.     

Influence of tetracycline exposure on the growth of wheat seedlings and the rhizosphere microbial community structure in hydroponic culture

In this study, the effects of tetracycline exposure on wheat growth and the microbial community structure in the rhizosphere were investigated under hydroponic culture conditions. Exposure to various concentrations of tetracycline resulted in significant suppression of the growth of wheat roots and shoots, with minimum doses of 0.8 mg L^?1 and 4 mg L^?1 resulting in inhibition rates of 32% and 15.4%, respectively. Complete inhibition of the growth of these two parts of wheat plants was observed in response to treatment with tetracycline at 20 mg L^?1 and 100 mg L^?1, respectively. However, the germination of wheat seeds was not sensitive to exposure to tetracycline. The effects of tetracycline exposure on the microbial community in the wheat rhizosphere were evaluated through traditional cultivation and molecular biological analyses. The cultivation results indicated that bacteria were the dominant population, being present in concentrations of 1× 10⁸–2.45× 10⁹CFUs mL^?1, although 39% to 87% inhibition occurred in response to tetracycline. The concentration of fungi increased in all tetracycline treated samples to 2.5 to 15.8 times that of the control. The highest concentration of fungi (4.27× 10⁸ CFU mL^?1) was observed in response to 60 mg L^?1 tetracycline after 15 days of cultivation. In this stage, a large amount of fungal colonies was observed on the surface of the culture solution, the wheat roots became rotted and the plants became atrophic or even died. Molecular biological analysis indicated that the bacterial community structure was significantly different in samples that were exposed to high levels of tetracycline (over 20 mg L^?1) than in samples that were exposed to lower concentrations. As the concentration of tetracycline increased, the diversity of the bacteria decreased. Additionally, several dominant sensitive species such as Sphingobacterium multivorum were suppressed by tetracycline, while some resistant species such as Acinetobacter sp. appeared or were conserved. The bacteria population tended to stabilize when the drug concentration exceeded 40 mg L^?1.