火电厂烟尘浓度测量的不确定度评定

根据不确定度评定的原理及方法,对重量法测定火电厂烟尘浓度进行不确定度评定,充分考虑测量重复性、烟气温度、烟气含氧量等,计算出火电厂烟尘浓度测量的扩展不确定度.     

川滇地区地震活动趋势再判断

川滇地区是中国大陆最显著的地震活动区域之一。结合该地区20世纪以来的地震数据,通过三元、四元和五元可公度计算、可公度系图谱构建及蝴蝶结构图分析,结果表明,在未来十年内的2015年和2017年前后川滇地区均有可能发生≥7.1级强烈地震,其中2015年的灾害信号最强。该研究旨在丰富可公度方法的灾害趋势判断案例,同时希望能为川滇地区地震灾害的监测提供一定的依据。     

原子荧光光谱仪测定底泥中砷含量的不确定度评定

介绍了原子荧光光谱仪测定底泥中砷含量的不确定度评定方法,分析和识别测量过程中不确定度的来源,较为全面地评定了测量不确定度。根据最小二乘法拟合计算工作曲线的标准不确定度,采用极差法评定测量次数较少时引起的标准不确定度。     

双曲线拟合法预测真空预压土体的沉降量及固结度

土体固结度是评价真空预压法加固土体效果的一个重要技术指标,而确定土体固结度的关键是土体最大沉降量的计算。本文结合工程实例,依据真空预压法施工前期土体沉降量的实测数据,利用双曲线拟合法进行拟合并预测土体最大沉降量及卸荷时的土体固结度,然后与常用的三点法预测结果进行对比,结果表明双曲线拟合法预测结果更加符合工程实际,且能保证工程的安全。     

GM(1,1)灰色模型在真空预压沉降预测中的应用

土体固结度是真空预压法加固土体效果的一个重要评价指标,地基最大沉降量的计算是确定土体固结度的关键。本文结合工程实例,分析了GM(1,1)灰色模型在真空预压沉降预测中的可行性,根据部分实测数据计算了地基最大沉降量及土体固结度,并与常用的三点法和双曲线法计算结果进行对比,结果表明GM(1,1)灰色模型的预测结果更符合工程实际。该研究对真空预压施工具有一定的指导意义。     

模糊评判在岩质边坡稳定性评价中的应用

在工程实践中,影响岩质边坡稳定性的因素众多,不同因素的影响程度不相同,具有不确定性,因此选择合适的方法对岩质边坡稳定性进行评价尤为关键。本文采用模糊综合评判方法对岩质边坡进行稳定性评价,首先阐明了如何建立模糊评判体系以及权重和隶属度的确定方法,然后以某岩质边坡为实例,采用模糊评判方法对其稳定性进行了评价,结果表明模糊评判的结果与实际情况较为吻合,说明该方法真实、有效,具有一定的借鉴意义。     

亚热带稻田生态系统CO2通量的季节变化特征

为估算和评价稻田生态系统碳源/汇强度及其对大气CO₂浓度变化的贡献,研究了稻田生态系统与大气间CO₂交换通量的季节变化特征及其影响因素.采用涡度相关技术对我国亚热带稻田生态系统CO₂交换通量进行了连续监测,在数据剔除、校正和差补的基础上,对瞬时CO₂通量值进行计算求得日CO₂通量值和年CO₂通量值,并对CO₂通量季节变化及其与主要气象因子的关系进行了探讨.结果表明,稻田生态系统光合吸收CO₂通量（GPP）、呼吸排放CO₂通量（R_eco）和净吸收CO₂通量（NEE）的季节变化均呈6～9月较高,1～5月和10～12月较低的对称分布.其中5～9月水稻生长时期的NEE总量占年总量的80%以上,对年NEE总量起决定性作用.光合有效辐射（PAR）和日平均气温（T_a）是GPP与NEE季节变化的最主要影响因子,二者与GPP和NEE分别存在显著的二元线性关系.年净吸收CO₂总量为2?475.6 g/(m²·a),这表明我国亚热带稻田生态系统是大气CO₂的汇.     

我国当前城乡建设用地置换的实践探索及问题剖析

当前我国城乡建设用地利用存在着城市建设用地指标紧缺、农村建设用地低效利用和城乡建设用地"双增"大量侵占耕地等问题。城乡建设用地增减挂钩政策推动下的城乡建设用地置换有望成为破解该问题的综合途径。2004年开始,伴随相关政策陆续出台,城乡建设用地置换实践在多个省市试点推进,其中江苏省万顷良田建设工程、天津市宅基地换房、山东省农村社区化、重庆市地票交易市场的实践较为典型。基于上述典型案例和系统要素分析,总结了实践的问题、根源与演进,认为目前系统中的要素与相应的操作环节中存在问题隐患且部分问题表现突出;实践中主要以涉及"非自愿"置换、补偿与保障不足、生产生活方式改变等的农民利益受损问题较为突出;问题的根源集中在三个方面,即国家层面的约束性的法律、法规、政策尚不健全,地方政府操作不合理和缺乏科学研究支撑。今后的实践中,应该建立统一的城乡土地市场并逐步完善政府主导下的城乡土地市场运行机制,建立科学合理的征地补偿机制,深入开展相关科学研究,遵循集约型用地增长模式,同小城镇建设紧密结合,注重保护村落景观风貌。     

Remediation of copper polluted red soils with clay materials

Attapulgite and montmorillonite were utilized to remediate heavy metal polluted red soils in Guixi City, Jiangxi Province, China. The e ects of clay minerals on availability, chemical distribution, and biotoxicity of Cu and Zn were evaluated. The results provided a reference for the rational application of clay materials to remediate heavy metal contaminated soils. From the sorption experiment, the maximum adsorbed Cu2+ by attapulgite and montmorillonite was 1501 and 3741 mg/kg, respectively. After polluted red soil was amended with attapulgite or montmorillonite and cultured at 30 and 60 days, soil pH increased significantly compared to the control. An 8% increase in the amount of montmorillonite in soil and 30 days incubation decreased acid exchangeable Cu by 24.7% compared to the control red soil. Acid exchangeable Cu decreased with increasing amounts of attapulgite and montmorillonite, with best remediation e ect reached at a dose of 8%. Results also showed that the Cu poisoning e ect on earthworms was reduced with the addition of attapulgite and montmorillonite. Montmorillonite showed the best e ect, with the addition of a 2% dose the mortality of earthworms decreased from 60% to zero compared to the control. Our results indicated that the bioavailability of Cu in soils was reduced more e ectively with the application of montmorillonite than attapulgite.     

Effect of chromium on accumulation and antioxidants in Cucumis utillissimus L.: Response under enhanced bioavailability condition

This study compares the accumulation of Cr(VI) and biochemical changes (total chlorophyll, carotenoid, protein, malondialdehyde (MDA) and cysteine contents) and roles of antioxidant enzymes (superoxide dismutase (SOD), guaiacol peroxidase (GPX), ascorbate peroxidase (APX)) in tolerance to metal induced stress in Cucumis utillissimus L. grown in Cr contaminated soil (CS) with garden soil (GS). Furthermore, Cr bioavailability was enhanced by ethylene diamine tetra-acetic acid (EDTA) addition to the soil to forecast the plant’s accumulation pattern at elevated Cr environment. Accumulation of Cr in the leaves of the plant increased with increase in substrate metals concentration. It further increased with the addition of EDTA by 1437% and 487% in GS and CS, respectively at the highest treatment level. The lipid peroxidation increased proportionately with increase in Cr accumulation in the leaves. All the activity of antioxidant enzymes (SOD, GPX and APX) and the level of cysteine increased with dose dependant manner. SOD and cysteine were observed to be higher in the GS than in CS, but APX and GPX were found to be higher in CS than in GS. The increase in GPX and APX activities with the increase in Cr concentration could be assumed that these two enzymes have a major role in the defense mechanism towards stress induced by Cr in C. utillissimus.