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21.
分别对国内外大型空间环境模拟器的真空系统配置进行了介绍,并对真空系统各个子系统的配置与技术特点进行了分析,重点针对大型空间环境模拟器真空系统中所需的真空抽气策略进行了研究,为后续超大型环境试验设备的研制和试验测试提供了参考。  相似文献   
22.
油气集输管道内防腐技术应用进展   总被引:1,自引:1,他引:0       下载免费PDF全文
针对油气田集输管道的内腐蚀问题,分别介绍了耐蚀材料、衬里技术、涂镀层技术与药剂防腐技术等管道内防腐技术及其现场应用效果,指出了耐蚀金属材料防腐效果显著,但存在经济效益差的缺点。为降低成本,选用双金属复合管替代耐蚀金属材料,但其焊缝位置腐蚀失效频发,成为制约其应用的薄弱环节。耐蚀非金属材料防腐效果显著,但耐高温性能与力学性能较差,受温度、压力与CO_2、H_2S、固体颗粒等介质成分的影响,衬里技术与涂镀层技术的应用范围受到限制。药剂防腐技术的防护效果与药剂类型、加药工艺密切相关,需要根据腐蚀工况监测结果进行实时调整。针对上述内防腐技术存在的问题,提出了未来内防腐技术的发展方向为改进现有内防腐技术存在的不足,提升其防护效果。同时,应开发防腐效果显著、经济成本低、施工简便、易于推广应用的防腐材料与防腐工艺技术。  相似文献   
23.
Consistent estimators of change and state becomes an issue when sample data come from a mix of permanent and temporary observation units. A joint maximum likelihood estimator of state and change creates estimates of state that depend on antecedent viz. posterior survey results and may differ from estimates of state derived from a single-date analysis of the sample data. A constrained estimator of change in relative categorical frequencies that eliminates this potential inconsistency is proposed and a model based estimator of their sampling variance is developed. The performance of the constrained estimator is quantified against six criteria and a joint maximum likelihood estimator in simulated sampling from 15 populations with three combinations of permanent and temporary samples, four to six categorical class attributes, and constant size between sampling dates. Bias of the constrained estimators was negligible but larger than for joint maximum likelihood estimators. Mean absolute deviations and variances of constrained estimators were generally at par with the joint estimators. Constrained estimators of root mean square errors and achieved coverage of nominal confidence intervals of constrained estimators were occasionally better. A generalized variance function for the constrained estimates of change is provided as a computational shortcut.  相似文献   
24.
通过对乌鲁木齐市的PM10和TSP数据的对比分析,找出PM10在TSP中所占比率(分担率)在采暖季和非采暖季的变化范围,从而使过去采集的TSP数据与PM10数据有一定的可比性,保证监测数据的连续可比。  相似文献   
25.
发光细菌法评价工业废水的毒性   总被引:5,自引:0,他引:5  
用发光细菌测定法估算了两城市污水对河道水体污染的分担率,评价了工厂排放废水的毒性,并据此确定了污染源监督管理中应优先治理的工厂(车间)废水。  相似文献   
26.
对色泽较深,含杂质量较高的废水加硅油I以抑制测定中蒸馏产生的泡沫.结果表明,在250ml水样中加硅油IO.10~1.25ml,即可收到理想效果.硅油I性质稳定,不随水蒸汽蒸出,对测定无干扰.  相似文献   
27.
连续5天腹腔注射同一剂量(1/5LD50)的合成洗涤剂,取小鼠骨髓细胞测定嗜多染色红细胞的微核率,研究表明,3种合成洗涤剂(加大香洗衣粉,洁牌餐具洗涤剂,恩威高级餐具洗洁精)使小鼠微核率有所增高,但恩威,洁牌餐具洗涤剂与对照无显著性差异。  相似文献   
28.
Surficial sediment samples collected from Kaohsiung Harbour and its nearby coast were analyzed for aliphatic hydrocarbons and parent polycyclic aromatic hydrocarbons (PAHs). According to our results, the average total concentrations of n-alkanes (n-C12 to C35) and aromatics (15 PAHs) were 4.33 µg g–1 dry weight (ranged 0.46–22.60) and 0.59 µg g–1 dry weight (ranged 0.09–1.75), respectively. The highest concentrations of aliphatic and aromatic hydrocarbons were recorded in stations near the estuaries of Qianzhen River and Love River, respectively. Aliphatic hydrocarbons in the samples indicate that there has been significant non-petrogenic, possibly terrestrial, contribution in the sediment of the open coast of Kaohsiung Harbour and that there has been dominant contribution from petrogenic sources in the sediment of the inner harbour. PAHs, detected in the samples, however, indicated a higher pyrolytic contribution in open-coast samples and a higher petrogenic contribution in the inner harbour. Overall, sediment concentrations of total alkanes in this study were comparable to those found in Victoria Harbour, Hong Kong and are higher than those found in Xiamen Harbour, China. Concentrations of total PAHs in inner Kaohsiung Harbour sediments were relatively lower than those found in Victoria Harbour, Hong Kong and Xiamen Harbour, China, but comparable to those found in Hsin-ta Harbour, Taiwan and Incheon Harbour, Korea. In comparison with several effect-based sediment quality guidelines, most PAH concentrations found in samples taken from inner harbour stations exceeded the Threshold Effect Level of Florida indicating a slight possibility of adverse effects.  相似文献   
29.
The distribution of actinomycetes in oil contaminated sandy loam ultisols of the Niger Delta region of Nigeria was studied to aid in understanding the effect of hydrocarbons on indigenous microbial population in tropical soils. The average total counts of actinomycetes in all the oil samples analysed was 103 cfu/g. Higher counts of actinomycetes were observed during the dry season than during the wet season. The counts of hydrocarbonoclastic actinomycetes correlated positively with the total count of actinomycetes.The actinomycetes were generally restricted to the top soil(0-10 cm soil depth) although a seemingly deeper(down to 40 cm soil depth) distribution was noticed in the dry season. The isolates included oil degrading species of Actinoplanes, Norcadia,Streptomyces and Streptosporangium. Their high oil utilization ability indicates their positive potential and role in the bioremediation of oil-spilled soils.  相似文献   
30.
Supplementing the nutrient requirement of crops through organic manures plays a key role in sustaining soil fertility, and crop productivity and reducing use of fossil fuels. Field experiments were conducted for 2 years at two different locations (i.e. Lucknow and Pantnagar) in Uttar Pradesh, India. The objectives of the study were to assess the herb and essential oil yields of Japanese mint (Mentha arvensis cv. Hy 77), and its nutrient accumulation under single and combined applications of organic manures and inorganic fertilizers (NPK). Changes in physical and chemical characteristics of the soils (Fluvisols, Mollisols) were also determined. Eight treatments comprising different combinations of NPK through inorganic fertilizers and farm yard manure (FYM) were compared. The distilled waste of mint after extraction of essential oil was recycled to soils in the plots to supplement the nutritional requirement of the succeeding mustard crop (Brassica juncea cv. Pusa Bold). Herb and essential oil yield of mint were significantly higher with combined application of organic and inorganic sources of nutrients as compared to single applications. Accumulation of N and P was at par under full inorganic and combined supply whereas, K accumulation was higher with the former. Soil organic C and pH after harvest of mint did not significantly differ among the treatments, but the level of mineralizable N, Olsen-P and NH4OAc extractable K were higher in soil with integrated supply of nutrients. Significant increase in soil water stable aggregates, organic C, available NPK and microbial biomass, and decrease in soil bulk density were observed with waste recycling over fertilizer application. These benefits were reflected in the seed and stubble yield of mustard which succeeded mint. This study indicates that combined application of inorganic fertilizers with organics helps in increasing the availability of nutrients and crop yield and provides a significant effect to the succeeding crop. Similarly, recycling crop residues reduces the need for fossil fuel based fertilizer, and helps in sustaining and restoring soil fertility in terms of available nutrients and major physical and chemical characteristics of the soil.  相似文献   
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