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621.
采用英国帝国化学公司(ICI)蒙德火灾爆炸毒性指数评价方法分析了硫化氢储罐区的潜在危险性,对储罐区采取安全措施前后的火灾、爆炸、中毒等危险进行预测,从硫化氢储罐区的安全管理和消防措施等方面提出了对策. 相似文献
622.
研究了铝-铬天青S(GAS)-溴化十六烷基吡啶(CPB)分光光度法测定水样中痕量铝的最佳实验条件。结果表明:铝-铬天青S(GAS)-溴化十六烷基吡啶(CPB)三元显色体系的最大吸收波长为640nm;.最佳显色时间30min;显色剂铬天青S(GAS)最佳用量2.00mL(0.5g/L);最佳显色pH5.5。在实验确定的最佳条件下,测定结果有较好的稳定性,较高的准确度。 相似文献
623.
通过对东胜矿区的流动沙丘设置油蒿沙障、乔灌造林和围封管护的技术方法,治理井田强度沙漠化面积65.94km~2,初步遏制住了目前100km~2开发建设区域的沙漠化危害,已获得显著的生态环境效益。 相似文献
624.
汞的地球化学行为取决于汞的物理化学性质.汞在地震活动过程中的异常变化十分明显,映震效能较好。通过分析主要震例发现,汞异常特征普遍表现为高值或正脉冲及其脉冲群。异常分布范围与震级大小有关。一般来说是在异常结束后发震,但也有的是在高值段或异常恢复段发震。异常一般出现于震前几天到几个月不等。 相似文献
625.
626.
三维溢油动态预报模式 总被引:18,自引:4,他引:18
基于“油粒子”概述建立了模拟海上溢油行为的三维数值模型。模型运用确定性方法模拟平流过程,采用随机性方法模拟湍流扩散过程,“粒子扩散”方法避开了“平流-扩散”传统数值方法所导致的伪扩散效应,同时将油由于自身特性和扩展与受环境动力作用的被动扩展融为一体,较好地解决了油膜的扩散和破裂问题,通过模拟结果与卫星遥感监测资料的比较表明,模拟的溢油漂移方向误差不超过20°,厚油区的分布面积与卫片资料基本一致。 相似文献
627.
Junhua Li Shoufang Kang Lixin Fu Jiming Hao 《Frontiers of Environmental Science & Engineering》2007,1(2):143-146
A highly effective Ag-Al2O3 catalyst was prepared using the in-situ sol-gel method, and characterized by surface area using nitrogen adsorption, scanning electron microscopy (SEM), and transmission electron microscopy (TEM) techniques. The catalyst performance was tested on a real lean-burn gasoline engine. Only unburned hydrocarbons and carbon monoxide in the exhaust were directly used as reductant (without any external reductant), the maximum NO x conversion could only reach 40% at 450°C. When an external reductant, ethanol was added, the average NO x conversion was greater than 60%. At exhaust gas temperature range of 350–500°C, the maximum NO x conversion reached about 90%. CO and HC could be efficiently oxidized with Pt-Al2O3 oxidation catalyst placed at the end of SCR converter. However, NO x conversion drastically decreased because of the oxidation of some intermediates to NO x again. The possible reaction mechanism was proposed as two typical processes, nitration, and reduction in HC-SCR over Ag-Al2O3. 相似文献
628.
Xiaofeng Guo Hongsheng Zhang Ling Kang Jinlin Du Wanbiao Li Yuanjing Zhu 《Environmental Fluid Mechanics》2007,7(5):421-437
Micrometeorological measurements were made over an irrigated rice paddy during the Huaihe River Basin Experiment (HUBEX) in
1999. This study addresses the quality control and gap filling strategy for the heat fluxes with the Bowen ratio energy balance
(BREB) method. It also endeavors to benefit future studies through comparing five methodologies to estimate the net water
exchange. First, a three-step quality control strategy is constructed. Its first two steps guarantee the correct flux directions
and reject suspicious data, respectively. The third step forbids supersaturation by considering the Bowen ratio ranges for
different flux combinations (termed as “scenarios”). The quality-controlled latent heat (LE) and sensible heat (H) fluxes fall in three scenarios, namely I (LE > 0, H > 0), II (LE > 0, H < 0), and IV (LE < 0, H < 0). Second, the Priestley–Taylor evaporation model (PTEM) is applied to fill the gaps of LE, while the energy balance relationship is used to gap-fill H, namely H = R
N
− G − LE (R
N
: net radiation; G: soil heat flux). Central to the success of this strategy is the idea to calibrate the Priestley–Taylor parameter (α) in
a scenario-specific manner. On average, α values are calibrated as 1.20 and 1.35 for scenario I and II, respectively. For
scenario IV, most α values lie in a narrow range, namely from 0.9 to 1.0. Then, α is calibrated as 0.97 to extend the applicability
of the PTEM to condensation (negative LE). The scenario-specific treatment explicitly explains the diurnal variation of α derived without distinguishing the scenarios.
Third, five methodologies are compared in the calculation of net water exchange, including PTEM-gap-filled BREB method (M1),
energy-balance-based eddy covariance method (M2), and three simplified models to estimate LE, respectively as R
N
− H, R
N
− G, and R
N
. A major finding is that G and H have a similar effect of about 3% in the net water exchange. Thus, if either is neglected, the net evaporation should be
slightly lowered to avoid overestimate, by 3% as a rule of thumb from this work. 相似文献
629.
630.
Competitive adsorption characteristics of Co2+, Ni2+, and Cr3+ by IRN-77 cation exchange resin in synthesized wastewater 总被引:4,自引:0,他引:4
Adsorption properties of Co2+, Ni2+, and Cr3+ on an Amberlite IRN-77 cation exchange resin were investigated in batch systems. Levels of adsorption rapidly approached an equilibrium state within 1 h. The adsorption characteristics of each metal onto the resin were accurately represented by Langmuir isotherms. Co2+ and Ni2+, which have an equivalent electrovalence, displayed similar levels of adsorption onto the resin when they coexisted in the solution. However, when Cr3+ was added to the solution it competitively replaced Co2+ and Ni2+ ions that had been previously adsorbed onto the resin, resulting in the desorption of these metals into the solution. The result was likely due to a higher adsorption affinity of Cr3+ relative to Co2+ and Ni2+. This implies that interactively competitive adsorption of multi-cations onto the resin should be thoroughly considered when contemplating the efficient operation of an ion exchange process in the treatment of industrial wastewater. 相似文献