高温高压下二辉橄榄岩的阻抗谱实验研究

 在1.0～4.0 GPa压力、1 073～1 573 K温度和10^-1～10⁷ Hz频率条件下,利用SARLTON-1260阻抗-增益/相位分析仪,就位测定了二辉橄榄岩的阻抗谱。实验结果表明：二辉橄榄岩的阻抗谱对频率具有很强的依赖性,并从阻抗谱的测试原理（颗粒内部、颗粒边缘、样品与电极间的导电机制）上做出了解释;温度是决定二辉橄榄岩电导率的一个重要物理参数,电导率随着温度的升高而增大,lg σ与1/T之间符合Arrenhius关系式;在高压实验中第一次将压力作为测量二辉橄榄岩电导率重要的约束因素,随着压力的增大,电阻率升高、电导率降低。     

高压对小麦种子发芽和幼苗生长的影响初探

 以豫麦18号小麦种子为材料，初步探索了不同压力和时间对不同处理的小麦种子发芽的影响，并对95 MPa压力、不同时间处理下发芽种子幼苗的生长情况进行测定。结果表明：在50~95 MPa压力下，直接真空包装的小麦种子均丧失发芽能力；在不同压力和时间下处理直接加水包装的小麦种子，种子发芽受到显著抑制；将水浸6 h再加水包装的小麦种子在95 MPa压力下处理4 h，能抑制小麦种子的发芽势和发芽率，但抑制强度较弱，也表明水可以有效降低高压对小麦种子的损伤。在95 MPa压力下、不同时间处理的直接加水包装的小麦种子幼苗的平均苗高和幼苗鲜重均大于对照。     

Φ1m平面镜的力学分析及实验研究

空间太阳望远镜(SST)的装校需要一个倒置的直径为1m的平面镜,此平面镜的面形精度决定了SST的装校成败。平面镜的支撑采用滑轮砝码机构,具有18个牵引点,每个牵引点的牵引力是独立可调的。在此支撑下,利用有限元分析方法分析了平面镜的变形情况,提出了用主动光学原理对牵引力大小进行优化的方法,计算出了保持平面镜具有良好面形时所需要的牵引力的大小。采用Ritchey_Common方法对平面镜进行了测量。测量结果表明,平面镜面形精度的均方根值优于λ/30(λ=633nm),满足了SST的装校要求。     

带弱"平台"皮秒光孤子的数值研究

通过数值求解变系数非线性薛定谔方程,发现光纤系统对带有弱“平台”的皮秒光孤子有独特的传输特性。在常参数光纤系统中,这种光孤子体现“呼吸”特性,而在特殊的分布参数光纤系统中,则能较平稳地传输。     

基于UGC大数据挖掘的大群体两阶段风险性应急决策方法

针对在重大突发事件应急决策大数据环境下决策者偏好的不确定性及偏离群体一致性导致的风险,提出一种基于UGC大数据挖掘的大群体两阶段风险性应急决策方法。首先,通过数据挖掘和自然语言处理方法从UGC中获取公众对事件的偏好信息并构建应急决策属性体系,利用TF-IDF方法结合专家评估信息确定属性权重;其次,建立一个意见开放式的两阶段决策流程,提出依据决策者意见的可靠度和准确度量化决策风险,利用聚类方法得到相应的成员权重,并使用TOPSIS法对决策方案进行排序。最后通过天津港“8·12”重大爆炸事故的案例分析和对比验证了所提出方法的可行性和有效性。     

Generalized Toda Mechanics Associated with Loop Algebras (L)(Cr) and (L)(Dr) and Their Reductions

We construct a class of integrable generalization of Toda mechanics with long-range interactions. These systems are associated with the loop algebras L(C_r) and L(D_r) in the sense that their Lax matrices can be realized in terms of the c=0 representations of the affine Lie algebras C⁽¹⁾_r and D⁽¹⁾_r and the interactions pattern involved bears the typical characters of the corresponding root systems. We present the equations of motion and the Hamiltonian structure. These generalized systems can be identified unambiguously by specifying the underlying loop algebra together with an ordered pair of integers (n,m). It turns out that different systems associated with the same underlying loop algebra but with different pairs of integers (n₁,m₁) and (n₂,m₂) with n₂<n₁ and m₂<m₁ can be related by a nested Hamiltonian reduction procedure. For all nontrivial generalizations, the extra coordinates besides the standard Toda variables are Poisson non-commute, and when either $n$ or m≥3, the Poisson structure for the extra coordinate variables becomes some Lie algebra (i.e. the extra variables appear linearly on the right-hand side of the Poisson brackets). In the quantum case, such generalizations will become systems with noncommutative variables without spoiling the integrability.     

Evolution of Dark Spatial Soliton in Quasi-phase-matched Quadratic Media

We theoretically investigate the evolvement of dark spatial soliton with cascading quadratic nonlinearity in quasi-phase-matched second harmonic generation. It is shown that the dark solitary wave can propagate stably when background intensity is large enough, in which diffraction of beam can be balanced by the cascading quadratic nonlinearity. We also analyze the influence of phase-mismatch on the stability of dark soliton propagation.     

Entanglement Evolution of a 2-Qutrit System Interacting with a Fermionic Bath

Based on the algebraic entanglement measure proposed [G. Vidal et al., Phys. Rev. A 65 (2002) 032314],we study the entanglement evolution of both pure quantum states and mixed ones of 2-qutrit system in a symmetrybroken environment consisting of a fermionic bath. Entanglement of states will decrease or remain constant under the influence of environment, and the class of states which remain unchanged has been found out.     

截断调和Bergman空间上Toeplitz算子的代数性质

本文首先讨论调截断和Bergman空间 $b_{n}^{2}$ 上拟齐次函数为符号的Toeplitz算子的有限秩乘积问题,其次考察两个以拟齐次函数为符号的Toeplitz算子的换位子与半换位子的有限秩问题.     

基于时变Copula模型的 基金收益率相依关系的应用研究

基于时变Copula模型,获得预测方差,确定单个基金收益率序列的边缘分布.利用常见的静态Copula和时变Copula模型对基金收益率序列间两两相依关系进行建模并进行对比分析.应用研究表明,基于MCMC方法的时变Copula模型能更有效地度量基金收益率序列的风险.