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991.
研究整装催化转化器中CO氧化的起燃过程.建立了起燃过程数学模型,通过数值计算,分析和讨论了起燃过程中温度的变化,气流性质和催化剂性质各种参数对转化器起燃性能的影响.结果表明,在起燃过程中,壁温峰值的位置逐渐向催化剂入口处移动;固相导热系数在反应点火前后对壁温峰值位置的影响不同;增大CO浓度、增大气体流速、降低气体温度会延迟催化剂的起燃;缩短催化剂长度、增大孔密度有利于起燃.参数分析有助于反应器的设计和建模. 相似文献
992.
澜沧铅矿井下有毒有害气体测评与控制 总被引:1,自引:0,他引:1
通过对井下作业点空气中CO、SO2、H2S、NO2和CO2等有毒有害气体的测定,将测定结果与进行比较,发现澜沧铅矿井下部分作业地点空气中CO、NO2和CO2浓度超过规定标准.根据分析、评价的结果,结合该矿实际情况,提出了控制井下有毒有害气体、改善井下空气质量的通风排毒等技术措施,以及防止井下有毒有害气体中毒的管理和个体防护措施.通过实施这些措施,使澜沧铅矿井下有毒有害气体得到了有效控制,其浓度达到了规定的要求. 相似文献
993.
994.
B. J. Blanchard A. T. C. Chang 《Journal of the American Water Resources Association》1983,19(5):803-810
ABSTRACT A study was made to determine if Seasat Synthetic Aperture Radar (SAR) data could be used to make practical estimates of soil moisture. Extensive ground measurements were collected at two primary sites near Guymon, Oklahoma, and Sublette, Kansas. The relative sensitivity of the SAR to differences in soil moisture, tillage roughness, and vegetation was determined. To validate the effects detected in the SAR data, an airborne scatterometer with a similar wavelength was flown repeatedly over the Guymon site. Soil moisture variations in the surface 2 cm and surface 15 cm of fields with bare soil, milo and alfalfa produce similar responses in the scattering coefficient from both systems. Roughness due to tillage in row crops produced as much as 12–15 dB increase in the scatterometer return. Most agricultural vegetation was effectively penetrated by the L-band frequencies; however, corn produced an exceptionally high radar return either standing or after combine harvesting. When corn had ripened, there was some evidence that tillage roughness could be detected through the canopy. Moderate tillage roughness produced by grain drill furrows caused over 12 dB increase in return when row directions changed from parallel to perpendicular with respect to the SAR look direction. Dramatic increases in return occurred when vegetation surfaces were wet. Increased radar returns from tillage roughness, some vegetation and wet vegetation surfaces, all dyanmic in nature, were significant and may limit the practical estimation of soil moisture from the radar data. 相似文献
995.
石油石化行业生产工艺复杂,容易发生各种环境事件。建立突发事件环境应急体系,对于提高企业综合处置能力,预防和控制次生灾害,促进油田企业全面、协调、可持续发展具有重要意义。文中给出了油田企业应急预案的基本框架及注意事项,阐述了应从哪几个方面进行环境风险的识别与评价以及削减环境风险的措施,并对环境应急体系长效机制的建立进行了探讨。 相似文献
996.
秦皇岛海滨森林公园森林景观改造探讨 总被引:1,自引:0,他引:1
秦皇岛海滨森林公园是秦皇岛沿海防护林的重要组成部分,也是秦皇岛重要的城市森林公园之一。针对秦皇岛海滨森林公园阔叶树多、针叶树少、树种单一、林龄老化、景观单调的现状.探讨了森林公园景观改造的原则、措施和技术,并描绘了景观改造后的效果。 相似文献
997.
Po‐Shan Yu Yu‐Chi Wang Tao‐Chang Yang Chun‐Chao Kuo 《Journal of the American Water Resources Association》2006,42(2):375-386
In Taiwan, the continuously increasing levels of rice imports are likely to result in surplus paddy fields. Hence, the surplus paddy fields may be developed into wetlands to increase ground water recharge, provide appropriate environments for wildlife, and most importantly, store flood water. This study developed a hydrological model incorporating the distributed rainfall‐runoff model based on the kinematics wave approach and the distributed tank model for simulation, respectively, in mountainous and flat areas. The hydrological model was found to simulate the rainfall‐runoff behavior well in the study area. Furthermore, a decision method based on the genetic algorithm concepts was proposed to give policy makers the optimal location and area size of paddy fields to construct wetlands for flood mitigation. 相似文献
998.
Biodegradation of nonylphenol in river sediment 总被引:1,自引:0,他引:1
We investigated the biodegradation of nonylphenol monoethoxylate (NP1EO) and nonylphenol (NP) by aerobic microbes in sediment samples collected at four sites along the Erren River in southern Taiwan. Aerobic degradation rate constants (k1) and half-lives (t1/2) for NP (2 microg g(-1)) ranged from 0.007 to 0.051 day(-1) and 13.6 to 99.0 days, respectively; for NP1EO (2 microg g(-1)) the ranges were 0.006 to 0.010 day(-1) and 69.3 to 115.5 days. Aerobic degradation rates for NP and NP1EO were enhanced by shaking and increased temperature, and delayed by the addition of Pb, Cd, Cu, Zn, phthalic acid esters (PAEs), and NaCl, as well as by reduced levels of ammonium, phosphate, and sulfate. Of the microorganism strains isolated from the sediment samples, we found that strain JC1 (identified as Pseudomonas sp.) expressed the best biodegrading ability. Also noted was the presence of 4'-amino-acetophenone, an intermediate product resulting from the aerobic degradation of NP by Pseudomonas sp. 相似文献
999.
Measurement of ultrafine particle size distributions from coal-, oil-, and gas-fired stationary combustion sources 总被引:1,自引:0,他引:1
Chang MC Chow JC Watson JG Hopke PK Yi SM England GC 《Journal of the Air & Waste Management Association (1995)》2004,54(12):1494-1505
Currently, we have limited knowledge of the physical and chemical properties of emitted primary combustion aerosols and the changes in those properties caused by nucleation, condensation growth of volatile species, and particle coagulations under dilution and cooling in the ambient air. A dilution chamber was deployed to sample exhaust from a pilot-scale furnace burning various fuels at a nominal heat input rate of 160 kW/h(-1) and 3% excess oxygen. The formation mechanisms of particles smaller than 420 nm in electrical mobility diameter were experimentally investigated by measurement with a Scanning Mobility Particle Sizer (SMPS) as a function of aging times, dilution air ratios, combustion exhaust temperatures, and fuel types. Particle formation in the dilution process is a complex mixture of nucleation, coagulation, and condensational growth, depending on the concentrations of available condensable species and solid or liquid particles (such as soot, ash) in combustion exhausts. The measured particle size distributions in number concentrations measured show peaks of particle number concentrations for medium sulfur bituminous coal, No. 6 fuel oil, and natural gas at 40-50 nm, 70-100 nm, and 15-25 nm, respectively. For No. 6 fuel oil and coal, the particle number concentration is constant in the range of a dilution air ratio of 50, but the number decreases as the dilution air ratio decreases to 10. However, for natural gas, the particle number concentration is higher at a dilution air ratio of 10 and decreases at dilution air ratios of 20-50. At a dilution air ratio of 10, severe particle coagulation occurs in a relatively short time. Samples taken at different combustion exhaust temperatures for these fuel types show higher particle number concentrations at 645 K than at 450 K. As the aging time of particles increases, the particles increase in size and the number concentrations decrease. The largest gradient of particle number distribution occurs within the first 10 sec after dilution but shows only minor differences between 10 and 80 sec. The lifetimes of the ultrafine particles are relatively short, with a scale on the order of a few seconds. Results from this study suggest that an aging time of 10 sec and a dilution air ratio of 20 are sufficient to obtain representative primary particle emission samples from stationary combustion sources. 相似文献
1000.
Relationship between electron donor and microorganism on the dechlorination of carbon tetrachloride by an anaerobic enrichment culture 总被引:1,自引:0,他引:1
An investigation involving the supplement of different concentrations of substrates and microorganisms was carried out under anaerobic condition to assess the feasibility of bioremediation of carbon tetrachloride (CCl4) with the amendment of low concentrations of auxiliary substrate and microorganisms. The concentrations of substrate and microorganisms ranged from 10 to 100 mg/l and from 3.7 × 104 to 3.7 × 106 cell/ml, respectively. The biotransformation rate of CCl4 increased progressively with the increase in the concentrations of the substrate and microorganisms. In the low biomass-amended system (3.7 × 104cells/ml), 28–71% and 57–96% of CCl4 removals were exhibited when 10–100 mg/l of acetate or glucose was supplemented, respectively, whereas nearly complete degradation of CCl4 was observed in the heavily inoculated systems (3.7 × 106 cells/ml). An addition of electron donor in the low microbial activity batches enhanced greater efficiency in dechlorination than in the high microbial activity batches. The second-order rate constants ranged from 0.0059 to 0.0092 l/mg/day in high biomass input system, while a two- to four-fold increase in rate constant was obtained in the low microbial activity system. This study indicates that biomass was the more important environmental parameter than substrate affecting the fate of CCl4. The addition of auxiliary substrates was effective only in low biomass-amended batches (0.56 mg-VSS/l) and diminished inversely with the increase of microbial concentration. 相似文献