不同精度格式的格子Boltzmann热模型的传热分析

通过在格子Boltzmann (LBM)热模型中添加参数项,使得在对应的宏观传热方程中,消除了一阶非线性误差项,具备二阶精度.通过Rayleigh-Benard对流数值试算,初步探索该二阶精度格式及其对应的一阶精度格式三个热模型的传热特征和适应性,并做出相应对比分析.针对一二阶精度模型在Ra数极高或热传导系数极大时,Nu数的计算与经验值相比出现较大偏差,分析LBM对应宏观热传导方程的截断误差后,在平衡分布函数中引进一个调节因子.通过调节对应宏观传热方程的截断误差项系数,校正Nu数的计算偏差,提高模拟精度,拓展模拟范围,增强了LBM作为一个数值方法在传热中的适应性.     

SU（3） Simple Group Model and New Z＇ Properties in Future Linear Colliders

In the SU（3） simple group model, the new neutral gauge boson Z＇ couples to pairs of SM fermions with couplings fixed in terms of the SM gauge couplings and depending only on the choice of the fermion embedding. In this paper, we calculate the contributions of this new particle to the processes e^＋e^-→l^＋l^-, bb^-, and cc^- and study the possibility of detecting this new particle via these processes in the future high-energy linear e^＋e^- collider（LC） experiments with √s= 500 GeV and ￡int= 340 fb^-1. We find that the new gauge boson Z＇ is most sensitive to the process e^＋e^-→b^＋b^-. As long as Mz,≤2 TeV , the absolute values of the relative correction parameter are larger than 5%. We calculate the forward-backward asymmetries and left-right asymmetries for the process e^＋e^-→c^＋c^-, with both the universal and anomaly-free fermion embeddings. Bounds on Z＇ masses are also estimated within 95% confidence level.     

Revised Geometric Measure of Entanglement for Multipartite and Continuous Variable Systems

Based on the revised geometric measure of entanglement （RGME） proposed by us [J. Phys. A： Math. Theor. 40 （2007） 3507], we obtain the RGME of multipartite state including three-qubit GHZ state, W state, and the generalized Smolin state （GSS） in the presence of noise and the two-mode squeezed thermal state. Moreover, we compare their RGME with geometric measure of entanglement （GME） and relative entropy of entanglement （RE）. The results indicate RGME is an appropriate measure of entanglement. Finally, we define the Gaussian GME which is an entangled monotone.     

Record of environmental change by α-cellulose δ13C of sphagnum peat at Shennongjia, 4000―1000 aBP

The Dajiuhu Basin at Shennongjia, located within typical East Asian Monsoon region, preserves a sub-alpine sphagnum peat deposition in its central area. The topmost 120 cm of the peat covers the last 4000 years according to AMS ^14C dating of pollen concentration. Carbon isotope of a-cellulose, extracted from sphagnum peat, provides a quantitative reconstruction of atmospheric relative humidity, based on transfer functions of C3 plants carbon isotopic fractionation equation and the bryophyte photosynthesis CO2 absorption rate equation. δ^13C, TOC and C/N variations reveal that the Dajiuhu area has experienced a long-term tendency to dry during 4000-1000 aBP, with a major transition happening around 3000 aBP. Four relative dry events are identified at 3400-3200, 3000-2600, 2200-2000 and 1600-1400 aBP, respectively, corresponding to those climate events documented in many global records. Three periodicities, 664 a, 302 a and 277 a enclosed in the atmospheric humidity of Dajiuhu are correlated to the cycles of solar activities. The weakening of East Asia summer monsoon during this period registered in the Dajiuhu peat is consistent with the synchronous weakening of Indian Monsoon. This trend may be attributed to gradual decrease of Northern Hemispheric summer solar insolation and the consequently southward migration of Intertropical Convergent Zone （ITCZ）.     

N5H5的结构性能的量子化学研究

采用了密度泛函B3LYP方法在6-311++G**基组上对N5H5异构体进行了理论计算,得到7种稳定构型,应用自然键轨道理论(NBO)和分子中的原子理论(AIM)分析了这些异构体的成键特征、相对稳定性. N-N键的键长与键临界点的电荷密度存在线性关系,键临界点的电荷密度ρ越大,N-N键的键长就越短. N原子孤对电子与相邻的氮氮键之间的相互作用是影响氮氮键长变化的主要因素. 立体交换排斥能和离域化能是影响异构体相对稳定性的重要因素. G3MP2计算结果表明所有异构体的生成热均为正,环状异构体的能量和生成热高     

高维抛物型方程的高精度恒稳定的交替格式

对高维抛物型方程问题,给出了两个高精度的交替方向格式(ADI格式).两个格式分别对2≤N≤4维和任意维数是恒稳定的,其局部截断误差阶均为O(γ2+h4).两个格式可以推广到一般常系数抛物型方程.数值例子与理论分析的结果相符合.     

基于相对密度的大棒材轧制对孔隙性缺陷压合影响研究

针对大棒材轧制生产过程中产品芯部孔洞及裂纹等孔隙性缺陷影响产品质量问题. 通过引入相对密度来间接表征轧件内部呈弥散分布的孔隙性缺陷,利用体积可压缩刚塑性有限元法模拟轧制过程中棒材芯部相对密度变化情况,根据模拟结果分析轧制工艺对轧件芯部孔隙性缺陷压合的影响情况,得到相应的变化规律. 将该研究结果应用于某钢厂棒材轧制工艺参数制定,产品质量明显提高,验证了所用方法的实用性和可靠性.     

坝陵河大桥隧道锚围岩力学特性原位试验研究

为全面认识坝陵河悬索桥西岸隧道锚的受力变形特性及安全稳定性,在分析研究锚碇区地层岩性特点基础上,利用相似性原理设计了与锚碇系统实际受力状态相适应的隧道锚原位模型试验系统,研究了原位试验加载及测试方法.试验成果表明,锚塞体混凝土和岩体在不同岩体条件下呈现出不同的变形特点:当岩体质量较好时,变形基本呈线性变化;当锚塞体周围岩体质量较差时,岩体的非线性变形特征明显.锚塞体与岩体之间的剪切残余变形表明锚塞体和岩体接触面在设计荷载作用下将产生较大的相对滑动.完整性较差岩体中的锚塞体变形远大于完整性较好情况下的锚塞体变形.     

高面板堆石坝工作性态的弹性和弹塑性对比分析

筑坝堆石料具有明显的非线性、压硬性、剪胀性和应力引起的各向异性,其应力变形特性直接影响到面板、接缝的应力变形情况.合理的堆石体本构模型是保证对高堆石坝进行正确预测分析的前提,对常用的邓肯E-B模型和南水双屈服面模型进行了对比性分析,最后在参数等价的基础上利用这两个模型对一座200 m级高面板坝进行了有限元分析,对造成计算差异的主要原因进行了探讨,为今后计算本构模型的选用提出了建议.     

基于多维诱导分量的拓展IOWA算子及其应用

受单一诱导分量不可排序的启发,提出了一种多维诱导分量的拓展IOWA(MIOWA)算子,它可以根据特定背景定义诱导分量的涵义,从不同侧面反映数据分量的若干特性.针对具有自主式特征的协商评价问题,定义了一个二维诱导分量的拓展IOWA算子,使得在多属性信息集结的过程中能够体现方案的相对优势和绝对优势;给出一个决定位置权向量的权数非独裁性协商规则下最大化orness水平的规划模型.最后给出一个算例说明了方法的可行性.