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11.
详细阐述了单水听器和水听器阵列进行海豚定距定位的几何模型,以及利用不同接收通道间的时延差计算空间坐标的方法,结合实验数据计算了海豚在水中的三维空间坐标和回声定位信号的声源级,并开展了海豚运动轨迹追踪分析。结果表明,相对于单水听器,水听器阵列对测量环境和海豚行为的限制较少,但对采集设备的同步性和硬件连接有较高要求。误差分析表明水听器阵列在大于3 m的距离,定位误差可降低到5%以下。研究结果为精确计算海豚发声源级及海豚的声呐性能及行为研究提供了技术支撑。 相似文献
12.
Surasa Maksasithorn Damien P. Debecker Piyasan Praserthdam Joongjai Panpranot Kongkiat Suriye Sirachaya Kunjara Na Ayudhya 《催化学报》2014,35(2):232-241
A WO3/SiO2 catalyst is used in industry to produce propylene from 2-butene and ethylene metathesis. Catalysts with various WO3 loading (4% to 10%) were prepared by impregnation and tested for the metathesis of ethene and trans-2-butene. Ion exchange of NaOH onto the WO3/SiO2 catalyst was used to mitigate the acidity of the catalysts in a controlled way. At low WO3 loading, the treatment with large amounts of NaOH resulted in a significant decrease in metathesis activity concomitant with significant W leaching and marked structural changes (XRD, Raman). At higher WO3 loading (6% to 10%), the treatment with NaOH mainly resulted in a decrease in acidity. FT-IR experiments after adsorption of pyridine showed that the Lewis acidic sites were poisoned by sodium. Nevertheless, the metathesis activity remained constant after the NaOH treatment. This suggested that the remaining acidity on the catalyst was enough to ensure the efficient formation of the carbene active sites. Interestingly, Na poisoning resulted in some modification of the selectivity. The mitigation of acidity was shown to favor propene selectivity over the formation of isomerization products (cis-2-butene, 1-butene, etc.). Moreover, treatment with NaOH led to a shorter induction period and reduced coke formation on the WO3/SiO2 catalyst. 相似文献
13.
Surasa Maksasithorn Damien P. Debecker Piyasan Praserthdam Joongjai Panpranot Kong- kiat Suriye Sirachaya Kunjara Na Ayudhya 《催化学报》2014,(2)
A WO3 /SiO2 catalyst is used in industry to produce propylene from 2-butene and ethylene metathe-sis. Catalysts with various WO3 loading(4% to 10%) were prepared by impregnation and tested for the metathesis of ethene and trans-2-butene. Ion exchange of NaOH onto the WO3/SiO2 catalyst was used to mitigate the acidity of the catalysts in a controlled way. At low WO3 loading, the treatment with large amounts of NaOH resulted in a significant decrease in metathesis activity concomitant with significant W leaching and marked structural changes(XRD, Raman). At higher WO3 loading (6% to 10%), the treatment with NaOH mainly resulted in a decrease in acidity. FT-IR experiments after adsorption of pyridine showed that the Lewis acidic sites were poisoned by sodium. Never-theless, the metathesis activity remained constant after the NaOH treatment. This suggested that the remaining acidity on the catalyst was enough to ensure the efficient formation of the carbene active sites. Interestingly, Na poisoning resulted in some modification of the selectivity. The mitigation of acidity was shown to favor propene selectivity over the formation of isomerization products (cis-2-butene, 1-butene, etc.). Moreover, treatment with NaOH led to a shorter induction period and reduced coke formation on the WO3 /SiO2 catalyst. 相似文献
14.
A new development to create the surface defect (Ti3+) on TiO2 was reported in this paper and compared to the common methods which must prepare the crystalline TiO2 in the first step prior, and then create the surface defect in the second step. In this work, the surface defect creation was performed in the first step coinciding with the crystalline TiO2 preparation using the sol-gel method. The creation was performed by varying the amounts of oxygen fed during calcination. Based on the CO2-temperature programmed desorption (CO2-TPD) and electron spin resonance (ESR) results, the surface defect (Ti3+) substantially increased with the amount of oxygen fed. Moreover, the samples resulting from calcination were used as photocatalysts for ethylene decomposition. The reactivity of those samples was also discussed. 相似文献
15.
Weena Phongsawat Benjamas Netivorruksa Kongkiat Suriye Siraprapha Dokjampa Piyasan Praserthdam Joongjai Panpranot 《天然气化学杂志》2012,(1):83-90
An unconventional metathesis of ethylene and 2-pentene over Re2O7/SiO2-Al2O3 catalysts has been studied as an alternative route for the production of propylene. Complete conversion of 2-pentene and propylene yield as high as 88 wt% were obtained under mild reaction conditions at 35°C and atmospheric pressure. Unlike the conventional metathesis of ethylene and 2-butenes in which isomerization is a competing side reaction, the isomerization of 1-butene product from the unconventional metathesis of ethylene and 2-pentene to 2-butenes can further react with excess ethylene in the feed, resulting in additional increase in propylene yield. The secondary metathesis reaction was found to be favored under ethylene/2-pentene (E/2P) molar ratio 3 and gas hourly space velocity (GHSV) 1000 h-1 at the reaction temperature of 35°C. No catalyst deactivation was observed during the 455 min time-on-stream under the selected reaction conditions. 相似文献