Formation of Giant Planets– An Attempt in Matching Observational Constraints

We present models of giant planet formation, taking into account migration and disk viscous evolution. We show that migration can significantly reduce the formation timescale bringing it in good agreement with typical observed disk lifetimes. We then present a model that produces a planet whose current location, core mass and total mass are comparable with the one of Jupiter. For this model, we calculate the enrichments in volatiles and compare them with the one measured by the Galileo probe. We show that our models can reproduce both the measured atmosphere enrichments and the constraints derived by Guillot et al. (2004), if we assume the accretion of planetesimals with ices/rocks ratio equal to 4, and that a substantial amount of CO₂ was present in vapor phase in the solar nebula, in agreement with ISM measurements.     

基于多分辨率复合阵列的未知信源数波达方向估计

为解决信源数未知情况下的多分辨率复合阵列波达方向(DOA)估计问题,将未知信源数的相干信号DOA估计算法拓展到多分辨率复合阵列中。本文研究了基于子阵空间谱联合的DOA估计方法,首先构造各个子阵列的托普利兹矩阵,并进行未知信源数的相干信号DOA估计;然后利用多分辨率复合阵互质的特性,构建联合代价函数进行解模糊。针对全范围搜索计算量大的不足,文中提出了单个不模糊区搜索,反推全部模糊角度的改进方案。仿真结果验证了所提方法的有效性,相比于全空间搜索的MUSIC算法和Capon算法,该算法无需信源数先验信息,且在信噪比大于15 dB和快拍数大于300时,其DOA估计的均方根误差仅为传统方法的1/2。     

Synthesis,chemistry and photochemistry of cyanobutadiyne (HCCCCCN)

Cyanobutadiyne has been synthesized starting from the mono or bistributylstannyl derivative of 1,3-butadiyne and p-toluenesulfonyl cyanide. The UV spectrum of HC₅N and the ¹³C NMR spectrum of the deuterocyanobutadiyne DC₅N have been recorded for the first time. Cyanobutadiyne has been detected in the photolysis of mixtures of gases observed on Titan. Its formation starting from cyanoacetylene and acetylene also occurs in the presence of huge amounts of dinitrogen, the major constituent of the Titan’s atmosphere. The application of these findings to the atmosphere of Titan is discussed. The chemistry and photochemistry of cyanobutadiyne have been investigated. A photoadduct has been observed in the photolysis of cyanoacetylene and ethanethiol and, a univocal synthesis of this compound was performed by a nucleophilic addition reaction.     

镁硫电池硫硒化合物正极材料的研究

镁硫电池是较具发展潜力的新型电池,其与锂硫电池相比具有体积能量密度高、安全性好的优点,在航空航天领域具有良好的应用前景。作为正极材料,硫理论比容量高、价格便宜,但导电性能不佳;硒导电性好,但理论比容量较低、价格较贵。制备了兼具两者优点的硫硒化合物(硫硒摩尔比分别为15∶1、1∶1、1∶15),并与微孔碳复合,发现硫硒比为1∶1的硫硒化合物/微孔碳复合正极材料SSe/C表现出最高的循环比容量,在50 mA·g~(-1)电流密度下45次循环后仍然能具有400 mAh·g~(-1)以上的比容量。因此,硫硒化合物是一种较具有潜力的镁硫电池正极材料。