放射性核素寿命计算方法的模拟研究

根据几种常用放射性核素的寿命计算方法,通过模拟数据研究了直接拟合法、对数时间法、极大似然法、观测时间受限时的极大似然法等四种寿命计算方法的适用范围。当观测时间不受限时,研究了在不同计数下寿命计算方法的适用范围。当观测时间受限时,研究了在不同观测时间窗口下寿命计算方法的适用范围。模拟中选用全剥离离子94mRu44+作为目标核素,得到了不同计数及不同观测时间窗口下的寿命及其误差,并给出了四种方法的适用范围。94mRu44+寿命的模拟结果与在兰州等时性质量谱仪上获得的实验结果在一倍标准偏差范围内一致,从而进一步验证了寿命计算方法的适用范围及模拟数据的可靠性。该模拟结果可为寿命测量实验设计提供理论依据和参考。     

二维叶栅气动特性的数值分析

过去研制一种新叶型需要做大量实验以确定其安装角、ｔ／ｂ（栅距／弦长）及出口几何角的使用范围，在可使用范围内还需要确定叶栅的攻角特性。这些在热力透平机械设计过程中是不可缺少的。随着计算机的发展及叶轮机械计算流体动力学的进步，人们已经可以通过主要是数值计算的方法来获得这些特性。本文给出了分析叶栅内二维流动特性的一种数值计算方祛。作者采用压力修正ＴＶＤ格式解雷诺平均的Ｎ－Ｓ方程组，壁面的湍流效应利用低雷诺数湍流模型模拟。运用本文方法计算了跨音及亚音叶栅内的湍流流动，并获得了某新叶型的使用范围及攻角特性。     

Shell Evolution Study for New Magic Number N =32 via Isochronous Mass Spectrometry

Recent results and progress of mass measurements of neutron-rich nuclei utilizing Isochronous Mass Spectrometry (IMS) based on the HIRFL-CSR complex at Lanzhou are reported. The nuclei of interest were produced through projectile fragmentation of primary 86Kr ions at a realistic energy of 460.65 MeV/u. After in-flight separation by the fragment separator RIBLL2, the fragments were injected and stored in the experimental storage ring CSRe, and their masses were determined from measurements of their revolution times. The re-determined masses were compared and evaluated with other mass measurements, and the impact of these evaluated masses on the shell evolution study is discussed.     

丙烯酸酯共聚物改性聚氨酯胶粘剂性能的研究

以2402酚醛树脂／聚氨酯为胶粘剂组分,得到具有优秀粘接强度的胶粘剂体系。通过自由基无规共聚合的方法合成出一系列不同玻璃化温度(-40～80℃)的聚丙烯酸酯,并对胶粘剂进行改性。结果表明：2402酚醛树脂的适量加入不仅可以改善胶粘剂对被粘面的浸润性、调节胶粘剂的粘度,还可以提高胶粘剂的粘接性能;使T剥离强度达到45N／cm;而丙烯酸酯共聚物的加入虽然降低了胶粘剂的粘接性能,使T剥离强度降至20～30N／cm,却可拓宽胶粘剂的阻尼温域,达到50℃。用SEM研究了不同组分对胶粘剂微观形貌的影响,用DMA研究了聚丙烯酸酯的改性对胶粘剂的阻尼性能的影响。     

全剥离离子94mRu44+的衰变研究

在兰州重离子加速器冷却储存环（HIRFL-CSR）上,用等时性质量谱仪首次研究了百微秒量级全剥离离子94mRu44+的衰变。94mRu44+由初级束流112Sn轰击Be靶产生,经过放射性束流线RIBLL2的筛选后注入到等时性设置的实验环CSRe中,并利用安装在实验环中的飞行时间探测器测量离子在CSRe中的循环周期。94mRu44+退激引起的质量改变会带来其循环周期的变化,由此直接观测到了94mRu44+退激到基态的过程。确定了本次实验中衰变事例探测的灵敏区间,并讨论了衰变发生时刻的测量精度。同时,测量了短寿命核素94mRu44+的质量,其半衰期约为100 μs,这是目前储存环质量谱仪测量的最短寿命核素的质量。The decay of the fully stripped ion 94mRu44+ in the order of one hundred microseconds has been studied for the first time by using the Isochronous Mass Spectrometry (IMS) at the HIRFL-CSR facility in Lanzhou. 94mRu44+ was produced via projectile fragmentation of a 112Sn primary beam bombarding on a 9Be production target. After the in-flight separation with RIBLL2, the ions were injected into the experimental ring (CSRe) and then stored there. The revolution times of the stored ions were measured by a Time-of-Flight (TOF) detector. Due to the mass change of a 94mRu44+ ion caused by its de-excitation to the ground state, hence the revolution time change, the decay process of 94mRu44+ could be directly observed in the CSRe. The sensitive window for detection of the decay events and the measurement precision of the decay time have been determined in this work. At the same time, we measured the mass of short-lived 94mRu44+ with the half-life about one hundred microseconds, which is the shortest among nuclides that have been studied by using storage-ring mass-spectrometry.     

缺中子核素101In低位同核异能态的首次观测

在兰州重离子加速器冷却储存环（HIRFL-CSR）上,用初级束流112Sn35+轰击了靶厚约10 mm的Be靶,产生了101In的基态和低位同核异能态。这些实验产生的碎片每25 s经过放射性束流线RIBLL2的筛选后注入到实验环CSRe中,利用飞行时间探测器测量离子在CSRe中的回旋周期。在此次实验中,磁场晃动会导致离子在环内的循环周期发生改变,传统的离子鉴别方法难以完成大部分离子的鉴别。通过发展和运用单次注入离子鉴别这一新的离子鉴别方法,有效地消除了磁场晃动对于离子鉴别的影响,并清楚地将101In基态和低位同核异能态鉴别出来,从而首次在实验中观测到101In的低位同核异能态。实验得到的激发能与理论外推值在112 keV的误差范围内一致,其低位同核异能态的寿命大于200 μs。Isochronous mass spectrometry has been applied to 112Sn projectile fragments at the HIRFL-CSR facility in Lanzhou. To produce short-lived nuclei of interest, we used projectile fragmentation of 112Sn35+ primary beams in a~10 mm thick 9Be production target. The fragments were selected and analyzed by RIBLL2 and injected into the experimental storage ring(CSRe) every 25 s. To measure revolution times of stored ions,we used a Time-Of-Flight detector installed in CSRe. A new particle identification method was developed to distinguish ions on the measured revolution time spectrum for each injection. Based on this method, the shifts of the revolution time due to instable dipole magnet fields can be corrected and the ground and isomeric states of 101In have been well-resolved. The measured excitation energy is consistent with the theoretical value in the error range of 112 keV. The lifetime of the isomeric states of 101In is more than 200 μs.     

汽封结构内部流动现象的数值研究

本文采用作者发展的叶轮机械通用计算程序ＧＡＰ１０对带围带汽封和隔板汽封结构的动 叶片排流场进行了三维数值模拟,并着重对汽封结构内部流动结构进行了分析。     

轴流透平通用叶型设计模块开发

1前言在叶轮机械气动热力设计体系中，叶型设计是最基本而关键的一环，叶型的好坏及选用适当与否对机组性能有非常大的影响。本文的工作是我们研制的多级轴流透平通流部分气动热力设计体系中的重要组成部分，其目的是要在满足结构、工艺、强度等约束条件的同时，高效、准确地设计出具有良好气动性能的叶型。本模块采用高档微机网络和中文NT操作系统作为支撑环境，选用商业化的CAD／CAM软件作为主要开发工具，在其基础上进行二次开发[1]。2叶型设计的类型与方法根据不同的已知条件，轴流透平叶型设计工作可分为三种类型：2．1已知初始叶…     

一种“后部加载”型透平静叶的设计

“后部加载”形式载荷分布能有效降低叶片通道二次流损失，从而显著提高流动效率，为此，设计了一种具有“后部加载”特性的透平静叶叶型。数值分析和实验研究显示该叶型能够降低三维通道总损失，同时又具有高强度及大范围攻角适应性等特点。     

一种新的k方程转捩湍流模型

本文在分析了针对充分发展湍流模型建立的k方程湍流模型模拟转捩流动的能力之后，构筑了一种新的Fμ函数及相应的k方程湍流模型．将该模型应用于数值求解NS方程，模拟了中等来流湍流度下零压力梯度平板捩报流动，并将部分计算结果与实验结果及经验关系进行了比较．