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141.
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设计了一款PWM控制模式降压式(buck)直流一直流转换器芯片。该芯片为电压反馈控制模式,内部补偿使得反馈控制有很好的线性和很快的负载响应而无需通过外部设计。芯片采用CMSC0.5μm BCD工艺实现。PSPICE仿真结果表明,输出电压只有大约50mY的纹波,静态电流为3mA左右。输出电压在低于0.5V时,芯片具有短路降频功能,工作频率由81KHz降到23KHz左右,输出负载由0.2A跳变到2A时具有很好的负载调整率,大约为0.2%,转换效率可以达到85%以上。 相似文献
143.
The influence of potential on the anodic dissolution of SIMFUEL (doped uranium dioxide) has been characterized over the range 0-500 mV (versus SCE). Cathodic stripping voltammetry was used to determine the changes in surface reactivity of UO2 in neutral solutions after different anodic oxidation timescales. Scanning electron microscopy (SEM) was used to view the damage to the SIMFUEL electrode surface which was minimal at E < 200 mV but present as local pits and eroded grains after oxidation at higher potentials. Long-term anodic oxidation at potentials below 200 mV suggests that local acidification can develop within surface asperities in the fuel and pores in corrosion product deposits accumulated on the electrode surface. 相似文献
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Lisbeth M Ottosen Ana T Lima Anne J Pedersen Alexandra B Ribeiro 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2006,81(4):553-559
The possibility of using fly ash from municipal solid waste incineration (MSWI) in, for example, concrete is considered. MSWI fly ash, however, has too high a concentration of heavy metals, which may cause leaching problems during use or problems with waste handling at the end of the lifetime of the concrete. The Cl content in MSWI fly ash is also too high and will cause corrosion problems in reinforced concrete. The possibility of removing some of the unwanted heavy metals (Cu and Pb) together with Cl from an MSWI fly ash suspended in water using an electrodialytic separation method was investigated. The removal of Pb and Cu was found to be highly pH dependent and the highest contents removed were 41 and 90%, respectively. The Cu concentration of the ash decreased from 2200 to 860 mg kg?1 but the Pb concentration increased from 8560 to 16 800 mg kg?1, showing that Pb is mainly found in the ash fraction that is least soluble. Hence electrodialytic treatment of the ash suspended in water is not a solution to improve the ash quality in terms of Pb. The water‐soluble Cl content per unit weight of the original ash was 12.4%. The removal of water‐soluble Cl was efficient and >98% of Cl was removed (calculated on the basis of mean initial and final concentrations). This result indicates that electrodialytic extraction may be a method that can be used for the removal of Cl from ash prior to its utilization in concrete. Copyright © 2006 Society of Chemical Industry 相似文献
147.
John R. Harbour 《Journal of the American Ceramic Society》1992,75(3):507-513
The volatilities of simulated, high-level nuclear waste glasses have been measured using thermogravimetric analysis (TGA). These volatilities were measured in the region of the glass transition temperature ( T g ) of the waste glasses, which is between 450° and 500°C. These data were obtained because the Waste Acceptance Preliminary Specifications require that no foreign materials be released into the canistered waste form upon heating of the canister to this glass transition temperature. In fact, all of the waste glass samples studied actually exhibited a net weight gain upon heating. This weight gain was shown to be due to oxygen uptake through oxidation of FeO. Powdered glass samples did show a small weight loss which was smaller in magnitude than the weight gain and was associated with water desorption. No true volatility was detected to the level of sensitivity (0.01 wt%) of the TGA instrument. This converts to a sensitivity of 330 μ g/m2 of glass surface and a corresponding minimum value of 41 mg of volatiles for each Defense Waste Processing Facility conistered waste form. TGA experiments carried out at higher temperatures (800°C) revealed that organic concentrations in the waste glasses are less than 0.01 wt%. Thus, these results demonstrate that the Defense Waste Processing Facility will be able to comply with the Waste Acceptance Preliminary Specifications on the exclusion of foreign materials from the canistered waste forms, after exposure to T g . 相似文献
148.
利用腈纶废丝合成絮凝剂PAN—DCD 总被引:10,自引:0,他引:10
本文以腈纶废丝为原料与双氰双胺在碱性溶液中反应,成功地制得含有多种活性基因的聚合物PAN-DCD,并用于染料废水脱色及炼油厂废水除油,除酚的处理研究,与常规使用的几种絮凝剂进行处理结果对照,实验结果表明:该产品单独使用处理效果明显优于其他絮凝剂,与聚铝复合使用处理效果更为理想。 相似文献
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探讨采用先进的A/O(厌氧菌 /好氧菌 )生物脱氮技术对己内酰胺生产废水进行处理的工作机理和工艺设计方法 ,分析了温度、溶解氧、pH值、进水碳氮比等参数对生物脱氮工艺过程的影响 ,并对其关键技术进行了研究 相似文献
150.