描述大形变核中对力的硬核Bose-Hubbard模型

讨论了一种描述大形变偶偶核邻近轨道对力相互作用近似的硬核Ｂｏｓｅ－Ｈｕｂｂａｒｄ模型．利用代数方法得到了该模型对激发谱和相应波函数的严格解．该结果可推广到具有任意自旋和有限格点的硬核Ｂｏｓｅ－Ｈｕｂｂａｒｄ和Ｆｅｒｍｉ－Ｈｕｂ－ｂａｒｄ模型中去．     

The slagging propensity of Zn-rich scrap tyre ash in reducing environments consisting of CO and CO2 and its promotion of the slagging of Si-rich coal ash

This study includes a comprehensive investigation on the ash slagging characteristics of zinc (Zn)-rich tyre ash and its interaction with silica (Si)-rich coal ash blended at different ratios in a 5% CO in CO₂ reducing environment. Such an environment is expected to occur near the burner in a combustor, as well as serves as a fundamental study on the slagging propensity upon the effect of CO, which is a principal reducing agent in a gasifier. An approach consisting of experimental studies using modified inclined plane (M-IP) methodology, advanced analytical techniques including the scanning electron microscopy (SEM) and x-ray photoelectron (XPS) spectroscopy, and thermodynamic equilibrium calculations were used to elaborate the slagging propensities of the single and blended ashes. Furthermore, the fate of Zn within tyre ash and its potential implications on the slagging properties were evaluated. Tyre ash easily melts to liquid slag upon increasing temperature compared to the silica-rich coal ash. Zinc does not evaporate but rather remains within tyre slag mostly as a hemimorphite (Zn₄(Si₂O₇)(OH))-like coordination structure attributing to the characteristic blue colour of tyre slag. The low ionic potential value of 2.7 for Zn²⁺ is characteristic of basic ions that have a greater tendency to depolymerise the Si-rich ash slag matrix and acts as a fluxing agent in ash slag. Moreover, it was proven that Zn²⁺ plays a synergistic role with Ca²⁺ in enhancing the flowability of the Si-rich slag remarkably. Furthermore, for the pure tyre slag, Zn was found to preferentially deposit at the corundum (Al₂O₃) substrate interface and even penetrate/react with the porous corundum, causing a strong corrosion on the substrate. However, blending of tyre ash with coal ash alleviates this problem by a preferred scavenging of Zn into the entire Si matrix, which in turn protects the corundum plate.     

张量积型Said-Ball曲面的预处理渐近迭代逼近法

为加快张量积型Said-Ball曲面渐近迭代逼近法的收敛速度,探讨了张量积型Said-Ball曲面渐近迭代逼近法的预处理技术。首先利用对角补偿约化技术构造了预处理子,然后结合矩阵Kronecker积性质,采取预处理渐近迭代逼近法求解张量积型Said-Ball曲面。为进一步降低计算量并提高算法的稳定性,利用广义极小残差法求解预处理方程,得到预处理渐近迭代逼近法的非精确求解方法。分析了预处理渐近迭代逼近法及非精确求解方法的收敛性。最后用数值实例说明预处理子能大大减小迭代矩阵的谱半径,令预处理技术及其非精确求解方法的计算效率明显提高。此外,由于对角补偿预处理子能改善配置矩阵的谱分布,因此也可用于对广义极小残差法的预处理,以改善其收敛性。     

Fabrication of Ni-Co binary oxide/reduced graphene oxide composite with high capacitance and cyclicity as efficient electrode for supercapacitors

Nickel-cobalt binary oxide/reduced graphene oxide (G-NCO) composite with high capacitance is synthesized via a mild method for electrochemical capacitors. G-NCO takes advantages of reduced graphene oxide (RGO) and nickel-cobalt binary oxide. As an appropriate matrix, RGO is beneficial to form homogeneous structure and improve the electron transport ability. The binary oxide owns more active sites than those of nickel oxide and cobalt oxide to promote the redox reaction. Attributed to the well crystallinity, homogeneous structure, increased active sites, and improved charge transfer property, the G-NCO composite exhibits highly enhanced electrochemical performance compared with G-NiO and G-Co₃O₄ composites. The specific capacitance of the G-NCO composite is about 1750 F g^?1 at 1 A g^?1 together with capacitance retention of 79 % (900/1138 F g^?1) over 10,000 cycles at 4 A g^?1. To research its practical application, an asymmetric supercapacitor with G-NCO as positive electrode and activated carbon as negative electrode was fabricated. The asymmetric device exhibits a prominent energy density of 37.7 Wh kg^?1 at a power density of 800 W kg^?1. The modified G-NCO composite shows great potential for high-capacity energy storage.     

Kalman滤波辅助的室内伪卫星相对定位算法

在室内伪卫星独立定位系统中, 伪卫星以及接收机的钟差会给定位精度带来非常大的误差. 针对这一问题, 提出了一种适用于室内环境的相对定位算法. 使用Kalman定位算法粗略计算接收机位置, 获得粗略基线, 建立室内相对定位模型, 得到载波相位双差和伪距双差. 载波相位双差通过互补Kalman滤波器来平滑伪距双差, 进一步得到精确基线, 获得接收机精确位置, 并将其代替Kalman定位算法的校正结果, 对接收机进行下一状态预测. 实验结果表明, 该算法具有较高的定位精度, 定位误差在20 cm以内. 关键词： 伪卫星 相对定位 双基线 Kalman滤波     

一种标定新方法在FTIR定量分析中的应用

利用傅里叶变换红外(FTIR)光谱技术可以对气体组分的浓度进行连续的在线定量分析。在定量分析过程中,对FTIR进行标定是非常重要的环节之一,直接关系到定量分析是否可以进行和定量分析的精度。本文提出了一种新的标定方法(称之为“积分法”),以CO、HCI和水蒸气为例完成的实验结果表明：这一方法与传统方法(标气法)相比具有许多优点,准确性和稳定性都很好;尤为重要的是,对于传统方法无法解决的常温下为液态的气体物质的标定问题,利用这一新方法可以迎刃而解,而且有很好的精度。     

On the classification of simple vertex operator algebras

Inspired by a recent work of Frenkel-Zhu, we study a class of (pre-)vertex operator algebras (voa) associated to the self-dual Lie algebras. Based on a few elementary structural results we propose thatV, the category of Z₊-graded prevoasV in whichV[0] is one-dimensional, is a proper setting in which to study and classify simple objects. The categoryV is organized into what we call the minimalk ^th types. We introduce a functor —which we call the Frenkel-Lepowsky-Meurman functor—that attaches to each object inV a Lie algebra. This is a key idea which leads us to a (relative) classification of thesimple minimal first type. We then study the set of all Virasoro structures on a fixed minimal first typeV, and show that they are in turn classified by the orbits of the automorphism group Aut((V)) in cent((V)). Many new examples of voas are given. Finally, we introduce a generalized Kac-Casimir operator and give a simple proof of the irreducibility of the prolongation modules over the affine Lie algebras.     

Structural, optical and electrical properties of Zn1−xCdxO thin films prepared by PLD

Ternary polycrystalline Zn_1−xCd_xO semiconductor films with cadmium content x ranging from 0 to 0.23 were obtained on quartz substrate by pulse laser deposited (PLD) technique. X-ray diffraction measurement revealed that all the films were single phase of wurtzite structure grown on c-axis orientation with its c-axis lattice constant increasing as the Cd content x increasing. Atomic force microscopy observation revealed that the grain size of Zn_1−xCd_xO films decreases continuously as the Cd content x increases. Both photoluminescence and optical measurements showed that the band gap decreases from 3.27 to 2.78 eV with increasing the Cd content x. The increase in Cd content x also leads to the broadening of the emission peak. The resistivity of Zn_1−xCd_xO films decreases evidently for higher values of Cd content x. The shift of PL emission to visible light as well as the decrease of resistivity makes the Zn_1−xCd_xO films potential candidate for optoelectronic device.     

Loschmidt echo of a central spin coupled to an XY spin chain: Role of three-site interaction

Effects of two types of three-site interaction, i.e., XZX+YZY and XZY−YZX, on Loschmidt Echo (LE) of a central spin coupled to an XY spin chain are studied. The dynamical evolution behaviors of the LE are investigated analytically and numerically. The XZX+YZY type of three-site interaction (α₁) can shift the critical points of the magnetic field λ. At the critical points |λ−α₁|=1, the decay of the LE is enhanced. The role of the XZY−YZX type of three-site interaction (α₂) depends on its strength. In some specific intervals, α₂ can remarkably delay the decay of the LE.