基于主成分分析和BP神经网络的综合安全评价模型

提出了基于主成分分析法和BP神经网络的综合安全评价模型.利用主成分分析法的数据降维功能对评价指标进行特征提取,选用合适的主成分作为神经网络的输入,构建网络拓扑结构.在建立多层次道路危险货物运输企业安全评价指标体系的基础上,采用MATLAB对企业安全现状进行实证仿真分析.结果表明,基于主成分分析法和BP神经网络的综合安全评价模型的评价结果优于其他评价模型.研究表明,本文得到的综合模型能够更加客观、准确地反映评价对象的实际情况.     

钢铁企业开放空间煤气扩散规律研究

研究目的是探索钢铁企业开放空间煤气泄漏的扩散规律和影响范围。采用matlab模拟煤气泄漏后CO的浓度分布和扩散距离规律。通过建立煤气泄漏扩散数学模型,对其影响煤气气扩散的主要因素进行了分析、探讨了煤气毒性范围的划分,并以某钢铁企业为实例进行数值模拟和计算。模拟结果显示,大气稳定度、风速对煤气泄漏扩散的浓度影响起着非常重要的作用。大气稳定度和风速会显著改变有害气体的扩散状态。在风速和泄漏增大时,煤气在开放空间扩散距离大,影响范围广,应合理布置煤气监控点,预防煤气中毒。     

废水处理与利用生态工程—Ⅰ特征和原理

文章叙述了在生存和可持续发展中废水处理的需要,当前在我国存在的主要问题,废水处理与利用生态工程主要特点,并与传统的污水处理工程比较。较详阐述了生态工程基本原理,整体、协调、自生、循环。     

天津市医疗垃圾管理信息系统设计研究

从用户需求分析、数据库结构设计、系统功能设计和用户界面设计四个方面 ,比较详细的介绍了天津市医疗垃圾管理信息系统 (MWMIS)的设计思想与设计方法及其主要功能特点。     

长江河口上边界床沙粒径的长期变化及其原因

大通水文站和泥沙观测断面位于长江河口的上边界。长江下游从大通（潮区界）至长江口门的距离长达680 km。20世纪80年代以来,长江流域日趋强烈的人类活动,显著改变了长江入海水文和泥沙数量和特性,从而对长江下游至河口动力地貌和动力沉积产生了显著影响。主要研究长江潮区界大通断面20世纪50年代以来床沙粒径的长期变化。1977~2004年床沙粒径 (〖WTBX〗d〖WTBZ〗50) 有一稳定增大的趋势,这主要是对上游河道悬沙来量持续减少的响应。值得注意的是床沙粗化过程是发生在该河床长期加积的背景上的。研究表明：导致床沙粒径粗化的原因,主要是上游河段进入本河段床沙粒径的增加和本河段冲淤过程中悬沙与床沙颗粒的交换。随着三峡水库的正常运行和其它大型水库的建设,预计未来几十年长江上游悬沙来量将进一步大幅度下降,可以预计,长江潮区界河段的床沙粒径将继续呈现增大的趋势。〖     

中国建设占用耕地与经济增长的退耦研究

采用退耦研究方法，探讨了近年来中国建设占用耕地与经济增长之间的退耦关系。并归纳其空间分异特点，进而对中国最严格耕地保护政策的实施效果进行了评价。研究结果表明，1998—2005年中国及其多数省份建设占用耕地规模已呈现相对于经济增长、城镇化发展以及总人口增长的退耦过程。在空间上，耕地占用相对于经济增长的退耦程度呈现中部大于西部，西部大于东部的特征；相对于城镇化水平增长的退耦程度呈现中部大于西部．西部略大于东部的特征；相对于总人口增长的退耦程度则呈现东部大于中部．中部大于西部的特征。研究表明近年来中国最严格耕地保护政策实施的积极效果已逐渐显现，经济增长、城镇化和人口增长驱动下的耕地占用压力已有所缓解。     

长江源区生态功能区划与生态系统管理

生态功能区划是近年来我国着力建设的一个新的关于资源与环境管理的框架。首先简要讨论了生态功能区划的性质,指出生态功能区划是基于生态系统的地理框架。与生态区比较,生态功能区强调人文活动对生态系统提供产品和服务能力的影响,并反映人类的价值判断。生态功能区划的最终目的是以生态系统的等级结构和尺度原则为基础,在不同尺度水平上实施“基于生态系统的管理”。以长江源区为例,进行了生态功能区划的实证分析。其基本认识是,按照生态系统的自然边界划分生态系统单元;进行生态系统描述和评价;在确定主导生态功能的基础上划分不同的生态功能区。最后讨论了按照生态系统原理对长江源生态功能分区进行管理和建设。     

Feasibility and simulation model of a pilot scale membrane bioreactor for wastewater treatment and reuse from Chinese traditional medicine

The lack and pollution of water resource make wastewater reuse necessary. The pilot scale long-term tests for submerged membrane bioreactor were conducted to treat the effluents of anaerobic or aerobic treatment process for the high-strength Chinese traditional medicine wastewater. This article was focused on the feasibility of the wastewater treatment and reuse at shorter hydraulic retention time （HRT） of 5.0, 3.2 and 2.13 h. MLSS growth, membrane flux, vacuum values and chemical cleaning periods were also investigated. The experimental results of treating two-phase anaerobic treatment effluent demonstrated that the CODfilt was less than 100 mg/L when the influent COD was between 500-10000 mg/L at HRT of 5.0 h, which could satisfy the normal discharged standard in China. The experimental results to treat cross flow aerobic reactor effluent demonstrated that the average value of CODfilt was 17.28 mg/L when the average value of influent COD was 192.84 mg/L at HRT of 2.13 h during 106 d, which could completely meet the normal standard for water reuse. The maximum MLSS and MLVSS reached 24000 and 14500 mg/L at HRT of 3.2 h respectively. Membrane flux had maximal resume degrees of 94.7% at vacuum value of 0.02 MPa after cleaning. Chemical cleaning periods of membrane module were 150 d. A simulation model of operational parameters was also established based on the theory of back propagation neural network and linear regression of traditional mathematical model. The simulation model showed that the optimum operational parameters were suggested as follows： HRT was 5.0 h, SRT was 100 d, the range of COD loading rate was between 10.664-20.451 kg/（m3.d）, the range of MLSS was between 7543-13694 mg/L.     

Laboratory-scale study of the suppression of PCDD/F emission during coal and MSW co-incineration

The experimental test of co-incinerating Chinese raw municipal solid waste （MSW） and coal in a laboratory-scale tubular reactor was first reported in present study, and the emission of normal gas components and the effects of the S/Cl molar ratio or coal mixing percentages on polychlorinated dibenzo-p-dioxins and dibenzofurans （PCDDs/Fs） emission were investigated and discussed. The results indicated that OCDD was the only PCDD homologues since others like TCDD-HpCDD was hardly detected, while as the categories of PCDF homologues were comparatively much more general. The amount of PCDD was much larger than that of PCDF in all operating conditions. Since ZPCDF/∑PCDD〈〈1, the dominant role of the precursor formation was proven in our experimental conductions. With increasing the coal addition to MSW （from 0 to 16%）, PCDD and PCDF were reduced considerably. Coal and MSW may suppress the PCDD/F emissions efficiently （over 95%） during the MSW incineration process. The PCDD/F suppression results of the present study could be helpful guidance to the industrial application of Chinese MSW and auxiliary coal co-incineration processes. The PCDD/F stack emission data of two industrial incinerators using co-incineration technology in China seem to have a great positive reduction of PCDDs/Fs.     

Biodegradation of methyl parathion by Acinetobacter radioresistens USTB-04

Biodegradation of methyl parathion (MP),a widely used organophosphorus pesticide,was investigated using a newly isolated bacterium strain Acinetobacter radioresistens USTB-04.MP at an initial concentration of 1200 mg/L could be totally biodegraded by A.radioresistens USTB-04 as the sole carbon source less than 4 d in the presence of phosphate and urea as phosphorus and nitrogen sources,respectively.Biodegradation of MP was also achieved using cell-free extract of A.radioresistens USTB-04.MP at an initial concentration of 130 mg/L was completely biodegraded in 2 h in the presence of cell-free extract with a protein concentration of 148.0 mg/L,which was increased with the increase of pH from 5.0 to 8.0.Contrary to published reports,no intermediate or final degradation metabolites of MP could be observed.Thus we suggest that the cleavage of C--C bond on the benzene ring other than P-O bond may be the biodegradation pathway of MP by A.radioresistens USTB-04.