提交时间： 2024-06-29
摘要： A new sub-critical reactorconcept is proposed as one accelerator splitting into multiple beams to drive the subcritical reactor in this work, which is so called Multi-Beam Accelerator Driven System (MB-ADS). The spallation target is designed as a unit similar to the fuel assembly. The high current proton beam is divided into multiple parts and injected into different targets located in the core to improve beam efficiency and flatten the spatial power distribution of the core. Based on different MB-ADSschemes, neutronics were conducted on the effects of beam splitting number, target assembly arrangements, fuel partitioning, and neutron data libraries. The results show that a reasonable multi-beam scheme can significantly improve the efficiency of the proton beam and flatten the power distribution of the reactor compared to the one target ADS scheme. Due to the improved beam efficiency, the beam density on the target window is greatly reduced.
分类： 地球科学 >> 地质学 提交时间： 2017-08-11 合作期刊: 《古脊椎动物学报》
摘要： Microraptorinae is a recently discovered subgroup of dromaeosaurid theropods, mostly comprising species from the Lower Cretaceous Jehol Group of western Liaoning, China. Here we describe a new microraptorine specimen from the Jiufotang Formation (the upper section of the Jehol Group) of Dapingfang, Chaoyang, Liaoning, which displays interesting morphological features not previously documented within Microraptorinae. Noteworthy are several osteological features, including dental and ischial ones, which are transitional between the condition of Sinornithosaurus and that of Microraptor. These features highlight the existence of a spectrum of morphological variation between Sinornithosaurus, which is more like a typical dromaeosaurid, and Microraptor, which shares many characteristics with troodontids. However, the taxonomic significance of these variations has not to be fully assessed yet. A feature deserving special mention is the fusion of the pubes to the ilia in this specimen, which has implications for the evolution of compound bones in theropods+. Our preliminary analysis suggests that many compound bones in birds have been formed by sequential fusion of multiple elements in a peramorphic process. 小盗龙亚科是驰龙科兽脚类恐龙中新近发现的一个亚群，多数属种产自中国辽宁西部下白垩统热河群。本文描记一件产自辽宁省朝阳县大平房地区九佛堂组(热河群上段)的小盗龙亚科的新标本，该标本具有一些未曾报道过的有趣形态特征。尤其值得关注的是，一些特征呈现出介于中国鸟龙和小盗龙之间的过渡状态，其中部分来自牙齿和坐骨。这些特征突出显示了在更接近典型驰龙类的中国鸟龙和具有许多伤齿龙科特征的小盗龙之间存在着一系列的形态变异。然而，这些变异特征在分类上的意义尚未得到充分评估。特别值得一提的是该标本中相互愈合的耻骨和肠骨，这一特征有助于阐明复合骨在兽脚类恐龙中的演化模式。初步分析显示许多鸟类的复合骨都是通过在过型形成过程中各组分的顺序愈合形成的。
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