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571.
572.
论江西省田塍资源及其开发利用   总被引:3,自引:0,他引:3  
田塍是耕地资源的重要组成部分。江西地处长江中下游南岸,田塍资源丰富,条件优越,具有很大的生产潜力。本文分析了江西田塍资源的现状和特点,阐述了开发利用田塍资源的必要性和优越性;提出了开发利用江西田塍资源的若干建议。  相似文献   
573.
此文介绍了采用Zn-22%Al超塑合金超塑成形出一般加工方法难以制造的定时凸轮塑料注射模型腔,具有周期短、成本低、质量高等特点。  相似文献   
574.
Oxidation of aniline by persulfate in aqueous solutions was investigated and the reaction kinetic rates under different temperature, persulfate concentration and pH conditions were examined in batch experiments. The results showed that, the aniline degradation followed pseudo first-order reaction model. Aniline degradation rate increased with increasing temperature or persulfate concentration. In the pH range of 3 to 11, a low aniline degradation rate was obtained at strong acid system (pH 3), while a high degradation rate was achieved at strong alkalinity (pH 11). Maximum aniline degradation occurred at pH 7 when the solution was in a weak level of acid and alkalinity (pH 5, 7 and 9). Produced intermediates during the oxidation process were identified using liquid chromatography-mass spectrometry technology. And nitrobenzene, 4-4’-diaminodiphenyl and 1-hydroxy-1,2-diphenylhydrazine have been identified as the major intermediates of aniline oxidation by persulfate and the degradation mechanism of aniline was also tentatively proposed.  相似文献   
575.
This study investigated the emission characteristics of ultrafine particles based on test bench and on-board measurements. The bench test results showed the ultrafine particle number concentration of the diesel engine to be in the range of (0.56-8.35) × 108 cm-3. The on-board measurement results illustrated that the ultrafine particles were strongly correlated with changes in real-world driving cycles. The particle number concentration was down to 2.0 × 106 cm-3 and 2.7 × 107 cm-3 under decelerating and idling operations and as high as 5.0 × 108 cm-3 under accelerating operation. It was also indicated that the particle number measured by the two methods increased with the growth of engine load at each engine speed in both cases. The particle number presented a "U" shaped distribution with changing speed at high engine load conditions, which implies that the particle number will reach its lowest level at medium engine speeds. The particle sizes of both measurements showed single mode distributions. The peak of particle size was located at about 50-80 nm in the accumulation mode particle range. Nucleation mode particles will significantly increase at low engine load operations like idling and decelerating caused by the high concentration of unburned organic compounds.  相似文献   
576.
基于传声器阵列的声源定位技术中的两个主要方法,STSF和Beamforming声源定位技术两者的实现方法不同。通过对STSF和Beamforming声源定位技术的推导,给出了两种测量技术适用的频率范围和空间范围,从理论上对其应用范围的差异进行了说明,并提出在实际测量中如何选择合适的声源定位方法。结合两种测量技术的特点,提出声源定位技术下一阶段研究的重点。  相似文献   
577.
黄德文 《环境工程》2012,(Z2):52-53,223
根据各类型好氧工艺运行的特点,结合多年设计经验,给出详细计算公式和参数选择范围,说明每个参数含义。  相似文献   
578.
用硫酸改性的粉煤灰作为吸附剂,处理含铬(Ⅵ)为5mg/L地下水,最佳条件为:pH=2,液固比10000:3,25℃下反应3h。处理后水样铬(VI)浓度0.03mg/L,满足(GB/T 14848-93)《地下水环境质量标准》。在不改变原水pH条件下,增加粉煤灰用量,水样中铬(VI)浓度也可由5mg/L降至0.05mg/L。同时,吸附剂对铬(VI)的吸附符合Freundlich和Langmuir等温线。  相似文献   
579.
黄亦平  李龙 《环境工程》2012,(Z2):232-235
描述了散货码头粉尘污染现状,分析比较了几种常用的积尘清扫方法。为了有效清扫散货码头的积尘,提出采用集中式真空吸尘系统。文章从系统形式、水力计算方法和工程实例等方面简单介绍了集中式真空吸尘系统。印尼Paiton燃煤电厂码头工程设计采用了集中式真空吸尘系统进行积尘清扫,工程建成投产一年多来,积尘清扫效果明显,有效地降低了粉尘污染。实例说明,真空吸尘是解决散货码头积尘清扫问题较为有效的方式。  相似文献   
580.
Manganese and ammonium pollution in surface water sources has become a serious issue.In this study, a pilot-scale filtration system was used to investigate the effect of ammonium on manganese removal during the simultaneous removal of ammonium and manganese from surface water using a manganese co-oxide filter film(MeO_x ). The results showed that the manganese removal efficiency of MeO_x in the absence of ammonium was high and stable, and the removal efficiency could reach 70% even at 5.5 °C. When the influent ammonium concentration was lower than 0.7 mg/L, ammonium and manganese could be removed simultaneously. However, at an ammonium concentration of 1.5 mg/L, the manganese removal efficiency of the filter gradually decreased with time(from 96% to 46.20%). Nevertheless, there was no impact of manganese on ammonium removal. The mechanism by which ammonium negatively affected manganese removal was investigated, demonstrating that ammonium affected manganese removal mainly through two possible mechanisms. On one hand, the decreased p H caused by ammonium oxidation was unfavorable for the oxidation of manganese by MeO_x ; on the other hand, the presence of ammonium slowed the growth of new MeO_x and retarded the increase in the specific surface area of the Me Ox-coated sand, and induced changes in the morphology and crystal structure of Me Ox. Consequently, the manganese removal efficiency of the filter decreased when ammonium was present in the inlet water.  相似文献   
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