The tube failures took place frequently in the superheater of 2x600MW units in a power plant. According to the condition of tube failures, the mechanical property and microstructure on running and failed tubes were te...The tube failures took place frequently in the superheater of 2x600MW units in a power plant. According to the condition of tube failures, the mechanical property and microstructure on running and failed tubes were tested and evaluated. The chemical composition and structure phase of inner oxide scale and deposit inside of the tubes were examined.The fractured surfaces of failed tube samples were observed. And the material examination was performed for original tube steels SA213-T91 and SA213-T22. The results show that raw materials of SA213-T91 and SA213-T22 tube in superheater are qualified. Besides, the characteristics of the SA213-T91 and SA213-T22 tube failure are typical short-term overheated rupture. The rupture temperature is located between two phase Ac1 ～ Ac3 of the two steels. It is recognized that putting SA213-T22 tubes in operation under the condition of long-term over heating causes the rupture of SA213-T91 and SA213-T22.展开更多
Position sensitive detector is very important for nuclear physics experiment. There several techniques can be used to fabricate position sensitive detector, for example, Si-surface barrier method, diffusion method, io...Position sensitive detector is very important for nuclear physics experiment. There several techniques can be used to fabricate position sensitive detector, for example, Si-surface barrier method, diffusion method, ion implantation and planar process etc. Among all the techniques mentioned above planar process is the best one. We have developed batch of position sensitive detector -- silicon multi-strip detector by using planar process.展开更多
Simulated research of internal loading and col- lecting and analyzing the samples from the lakes were carried out before and after dredging in polluted suburb lakes, Wuli Lake (Wuxi City) and Xuanwu Lake (Nanjing City...Simulated research of internal loading and col- lecting and analyzing the samples from the lakes were carried out before and after dredging in polluted suburb lakes, Wuli Lake (Wuxi City) and Xuanwu Lake (Nanjing City). The research results showed that dredging can in- hibit internal loadings in a certain degree in a short term. The discrepancy of dredging effect and technical level, namely dredging quality, by different dredging methods will result in a difference of control of lake internal Ioad- ings. The internal Ioadings’ reversion will gradually ap- pear along with the bio-geochemical processes, including suspended particle precipi-tation, hydrodynamic distur- bance and microbio-transfor-mation. The reversion rate mainly depends on the dredging method and the change of interfacial processes on the new-born surface layer. The higher nutrient contents and organic matter in the sedi- ment will enhance water-sediment interfa-cial processes and nutrients regeneration. It is very impor-tant to study the physicochemicai and biological character of lacustrine sediments before dredging for determining the dredging methods and predicting their environmental ef- fect.展开更多
If we classify the spoken English test (SET) according to the time a candidate is scored, we will probably have three types——direct, indirect and semi-direct SET. Direct SET is a traditional test type in which the a...If we classify the spoken English test (SET) according to the time a candidate is scored, we will probably have three types——direct, indirect and semi-direct SET. Direct SET is a traditional test type in which the assessor scores the performance of the candidates when they are in the test. In an indirect test, the performance of candidates is videoed展开更多
文摘The tube failures took place frequently in the superheater of 2x600MW units in a power plant. According to the condition of tube failures, the mechanical property and microstructure on running and failed tubes were tested and evaluated. The chemical composition and structure phase of inner oxide scale and deposit inside of the tubes were examined.The fractured surfaces of failed tube samples were observed. And the material examination was performed for original tube steels SA213-T91 and SA213-T22. The results show that raw materials of SA213-T91 and SA213-T22 tube in superheater are qualified. Besides, the characteristics of the SA213-T91 and SA213-T22 tube failure are typical short-term overheated rupture. The rupture temperature is located between two phase Ac1 ～ Ac3 of the two steels. It is recognized that putting SA213-T22 tubes in operation under the condition of long-term over heating causes the rupture of SA213-T91 and SA213-T22.
文摘Position sensitive detector is very important for nuclear physics experiment. There several techniques can be used to fabricate position sensitive detector, for example, Si-surface barrier method, diffusion method, ion implantation and planar process etc. Among all the techniques mentioned above planar process is the best one. We have developed batch of position sensitive detector -- silicon multi-strip detector by using planar process.
文摘Simulated research of internal loading and col- lecting and analyzing the samples from the lakes were carried out before and after dredging in polluted suburb lakes, Wuli Lake (Wuxi City) and Xuanwu Lake (Nanjing City). The research results showed that dredging can in- hibit internal loadings in a certain degree in a short term. The discrepancy of dredging effect and technical level, namely dredging quality, by different dredging methods will result in a difference of control of lake internal Ioad- ings. The internal Ioadings’ reversion will gradually ap- pear along with the bio-geochemical processes, including suspended particle precipi-tation, hydrodynamic distur- bance and microbio-transfor-mation. The reversion rate mainly depends on the dredging method and the change of interfacial processes on the new-born surface layer. The higher nutrient contents and organic matter in the sedi- ment will enhance water-sediment interfa-cial processes and nutrients regeneration. It is very impor-tant to study the physicochemicai and biological character of lacustrine sediments before dredging for determining the dredging methods and predicting their environmental ef- fect.
文摘If we classify the spoken English test (SET) according to the time a candidate is scored, we will probably have three types——direct, indirect and semi-direct SET. Direct SET is a traditional test type in which the assessor scores the performance of the candidates when they are in the test. In an indirect test, the performance of candidates is videoed
