升温热冲击环境下超高温陶瓷材料抗热震性能的热-损伤模型

在现有的抗热震理论基础上考虑到超高温陶瓷材料热物理性能对温度的敏感性及损伤在其使役历程中随温度的演化,建立了适用于升温服役环境下表征超高温陶瓷材料抗热震性能的热-损伤模型。该模型考虑了微裂纹尺寸、密度、热冲击环境温度等因素对材料抗热震性能的影响。利用此模型研究了超高温陶瓷材料在升温服役环境下损伤以微裂纹形核规律演化时对其抗热震性能的影响。从理论上验证了基于材料微结构设计思想在制备超高温陶瓷材料时,引进一定密度一定尺寸的微裂纹并控制其随温度演化规律以形核方式进行,既可以使材料保持较高的强度又能大幅度提升材料的抗热震性能。     

噪声对漂移室性能影响的模拟研究

利用蒙特卡罗方法模拟了漂移室的随机噪声和对其性能的影响,分别考虑了击中丝和非击中丝的时间道和电荷道的噪声,给出了径迹效率和动量分辨随噪声水平和噪声分布的变化情况.     

Calibration study of the X-T relation for the BESⅢ drift chamber

Offline calibration plays an important role in BES offline data processing. In order to achieve good spatial and momentum resolution, it is necessary to implement high precision offline calibration for the BES drift chamber. This paper studies the time-to-distance relations, which are important calibration constants for track reconstruction. The parameterization of the time-to-distance relation, studies of left-right asymmetry and studies of variation with entrance angle are performed. The impact of dead channels on the time-to-distance relation is given special attention in order to reduce the shift in measured momentum for tracks passing near dead cells. Finally we present the resolutions for barrel Bhabha events(|cos θ|< 0.8) from a J/ψ data set taken in 2012. The average spatial resolution is 123 μm and the momentum resolution for 1.548 Ge V/c Bhabha tracks is 11.9 Me V/c.     

北京谱仪Ⅱ顶点探测器的离线刻度

介绍了在VCJULI基础上对北京谱仪Ⅱ顶点探测器进行离线刻度的方法,包括整体T0的获得、单丝零时间t0的扣除、丝位的修正、顶点探测器相对于主漂移室位置的校正以及漂移时间一漂移距离关系的修正等.并由此给出了北京谱仪Ⅱ顶点探测器的主要参数:空间分辨好于100μm.     

北京谱仪桶部簇射计数器径迹重建方法

介绍了北京谱仪桶部簇射计数器径迹的重建方法,包括簇射径迹(独立簇射)的寻找、簇射的劈裂与合并等;并讨论了重建的性能和结果.     

顶夸克已被发现

顶夸克已被发现１９９５年３月２日，美国费米国家实验室召开学术报告会，正式宣布顶夸克已被发现。在会上，ＣＤＦ和Ｄ０合作组分别报告了它们的实验结果。ＣＤＦ测得顶夸克质量为１７６±８±１０ＧｅＶ／ｃ２，顶夸克对的产生截面为６．８而Ｄ０测得顶夸克质量为１９９...     

分子网络多靶标筛选的粒子群数值模拟法

当前对于疾病分子网络的治疗多采用多靶标药物治疗。多靶标药物治疗共分为两步,首先是筛选潜在的药物靶标,其次利用筛选出的药物靶标进行组合,进而得到有效的抑制方案。但现有算法耗时太多,本文使用花生四烯酸(Arachidonic acid)炎症代谢网络作为一个具体算例,使用改进并行的粒子群算法进行多靶标筛选优化,不仅能够得到药物靶标的有效组合,而且根据进程的个数可以使计算时间达到数倍的提高。     

The temperature-dependent fracture strength model for ultra-high temperature ceramics

Breaking down the entire structure of a material implies severing all the bonds between its atoms either by applying work or by heat transfer. Because bond-breaking is indifferent to either means, there is a kind of equivalence between heat energy and strain energy. Based on this equivalence, we assume the existence of a constant maximum storage of energy that includes both the strain energy and the corresponding equivalent heat energy. A temperaturedependent fracture strength model is then developed for ultrahigh temperature ceramics （UHTCs）. Model predictions for UHTCs, HfB2, TiC and ZrB2, are presented and compared with the experimental results. These predictions are found to be largely consistent with experimental results.     

热环境对超高温陶瓷材料抗热震性能的影响

基于超高温陶瓷材料相关材料参数对温度的敏感性,以现有的抗热震断裂评价理论为基础,通过考虑温度对超高温陶瓷材料物理性能的影响,探讨了热震温度范围内热应力衰减系数、表面热传递系数、热冲击初始环境温度等热环境参数对抗热冲击阻力参数、断裂临界温差和断裂临界温度的影响.