返修次数对S30408不锈钢焊接热影响区组织性能的影响

为进一步研究返修次数对焊接热影响区组织与性能的影响,本文借助S30408不锈钢氩弧焊焊接接头的返修,针对焊接接头进行显微硬度测试、室温拉伸试验、夏比冲击试验,并观察和分析了焊缝断口形貌。结果表明：焊缝返修次数不超过2次的情况下,焊接接头显微硬度略有下降,焊接返修3次时显微硬度明显降低;在不超过3次返修的情况下,焊接接头的强度、塑性和韧性随着返修次数的增加未出现明显的恶化趋势,返修次数与焊缝及热影响区金属的力学性能之间没有明显的相互关系。     

不同污泥浓度对生物沥滤过程的影响

以硫酸亚铁盐作为底物,氧化亚铁硫杆菌（Thiobacillus ferrooxidans）为主要沥滤微生物,在底物投配比为10 g/L,温度为25℃,曝气量为1 L/min的条件下,对5种不同浓度的桂林城市污泥中重金属进行生物沥滤试验。结果表明,生物沥滤的污泥浓度宜控制在25.6 g/L,沥滤3 d后,污泥中超标元素Cu、Zn和Cd的去除率分别达到58.17%、75.90%和93.64%,沥滤处理后污泥中残余重金属含量符合污泥农用的国家标准。     

基于Level Set方法的风暴追踪

利用现代计算机技术和信息处理技术,建立灾害性天气预警系统,是对灾害性天气进行识别和预报的最有效手段之一.研究探索风暴运动过程中多普勒雷达图像的数据处理和算法优化,是预警系统工作中的关键技术.基于计算机技术,应用TITAN算法及改进的Level set方法可以较好地实现对雷达图像中风暴体的追踪,提高灾害性天气预警效率.     

Effect of Sb dopant amount on the structure and electrocatalytic capability of Ti/Sb-SnO2 electrodes in the oxidation of 4-chlorophenol

Ti/Sb-SnO_2 anodes were prepared by thermal decomposition to examine the influence',of the amount of Sb dopant on the structure and electrocatalytic capability of the electrodes in the oxidation of 4-chlorophenol.The physicochemical properties of the Sb-SnO_2 coating were markedly influenced by different amounts of Sb dopant.The electrodes,which contained 5% Sb dopant in the coating, presented a much more homogenous surface and much smaller mud-cracks,compared with Ti/Sb-SnO_2 electrodes containing 10% or 15% Sb dopant,which exibited larger mud cracks and pores on the surface.However,the main microstructure remained unchanged with the addition of the Sb dopant.No new crystal phase was observed by X-ray diffraction(XRD).The electrochemical oxidation of 4-chlorophenol on the Ti/SnO_2 electrode with 5% Sb dopant was inclined to electrochemical combustion;while for those containing more Sb dopant,intermediate species were accumulated.The electrodes with 5% Sb dopant showed the highest efficiency in the bulk electrolysis of 4-chlorophenol at a current density of 20 mA/cm~2 for 180 min;and the removal rates of 4-chlorophenol and COD were 51.0% and 48.9%,respectively.     

Nitrogen interception in floodwater of rice field in Taihu region of China

A field experiment located in Taihu Lake Basin of China was conducted,by application of urea or a mixture of urea with manure, to elucidate the interception of nitrogen(N)export in a typical rice field through"zero-drainage water management"combined with sound irrigation,rainfall forecasting and field drying,N concentrations in floodwater rapidly declined before the first event of field drying after three split fertilizations,and subsequently tended to retum to the background level.Before the first field drying,total particulate nitrogen(TPN)was the predominant N form in floodwater of plots with no N input,dissolved inorganic nitrogen(DIN)on plots that received urea only,and dissolved organic nitrogen(DON)on plots treated with the mixture of urea and manure.Thereafter TPN became the major form.No N export was found from the rice field,but total nitrogen(TN)of 15.8 kg/hm~2 was remained,mainly due to soil N sorption.The results recommended the zero-drainage water management for full-scale areas for minimizing N export.     

Whole Effluent Toxicity (WET) Tests on Wastewater Treatment Plants with Daphnia magna and Selenastrum capricornutum

Whole effluent toxicity (WET) tests, with Daphnia magna and Selenastrum capricornutum, were introduced to evaluate the biological toxicities of effluents from the wastewater treatment plants (WWTPs) in Korea. In WET tests of WWTPs effluents, 33.3% (33/99) for D. magna and 92.6% (75/81) for S. capricornutum revealed greater than 1 toxic unit (TU), even though all the treatment plants investigated were operating in compliance with the regulations, as assessed using conventional monitoring methods (i.e., BOD and total concentration of N or P, etc). There were only minor differences in toxicities according to the types of influents (municipal and agro-industrial) in all treatment plants. However, the effluents treated by an activated sludge treatment process were found to exhibit significantly lower toxicity than those treated by rotating biological contactor (RBC) and extended aeration processes. The seasonal variations in the toxicity were lower in the summer compared to winter, which may have been due to the rainfall received to the sewage intake system during the former period. The impact of WET on river water was also investigated based on the discharge volume. At sites A and B, the total impact of toxicity to stream and river waters was observed to be 70.9% and 90.4% for D. magna and S. capricornutum, respectively. The other four small treatment plants (sites F, G, H and I), with relative discharging volumes between 0.001 and 0.002, contribute less than 1% to the total toxicity.     

蒸发过程早期渗滤液中有机酸挥发规律研究

对早期填埋场渗滤液进行了常规和载气蒸发实验,通过定时分批截留冷凝液并测定其TOC和挥发性脂肪酸（volatile fatty acids, VFAs）浓度,研究了不同pH条件下早期渗滤液中有机污染物的挥发规律.结果表明,pH=4时蒸发冷凝液中TOC呈由高而低的变化趋势,pH=7时TOC变化趋势截然相反.冷凝液中VFAs（乙酸除外）浓度变化规律与TOC相似,并且结构越复杂相对挥发速率越大.分析表明,早期渗滤液蒸发冷凝液中有机物主要由VFAs组成.是否具有载气及载气量多少对早期渗滤液有机物蒸发的影响不明显.     

第二松花江中PCBs与有机氯农药的迁移和分布

研究了PCBs和有机氯农药在第二松花江中的存在、迁移和分布.它们能通过吸附和鱼类摄取而在底泥和鱼体中富集,其分配比约为1:50:10000:     

Model testing using data on 137Cs from Chernobyl fallout in the Iput River catchment area of Russia

Data collected for 10 years following the Chernobyl accident in 1986 have provided a unique opportunity to test the reliability of computer models for contamination of terrestrial and aquatic environments. The Iput River scenario was used by the Dose Reconstruction Working Group of the BIOMASS (Biosphere Modelling and Assessment Methods) programme. The test area was one of the most highly contaminated areas in Russia following the accident, with an average contamination density of 137Cs of 800,000 Bq m-2 and localized contamination up to 1,500,000 Bq m-2, and a variety of countermeasures that were implemented in the test area had to be considered in the modelling exercise. Difficulties encountered during the exercise included averaging of data to account for uneven contamination of the test area, simulating the downward migration and changes in bioavailability of 137Cs in soil, and modelling the effectiveness of countermeasures. The accuracy of model predictions is dependent at least in part on the experience and judgment of the participant in interpretation of input information, selection of parameter values, and treatment of uncertainties.