有向图覆盖的Zeta函数

Mizuno和Sato定义了有向图的Zeta函数(见Linear Algebra Appl.,2001,336:181-190),它可用来计算有向图中具有给定长度的所有圈的个数.给出了任意有向图的覆盖的Zeta函数的计算公式.作为推论,覆叠重数为2,3和4的任意有向图覆盖(正则或非正则)的Zeta函数被计算出来,同时也计算了Cayley有向图的Zeta函数.     

A SIMPLE MODEL TO ESTIMATE THE IMPACT FORCE INDUCED BY PISTON SLAP

The dynamics of piston's secondary motion (lateral and rotational motion) across the clearance between piston and cylinder inner wall of reciprocating machines are analyzed. This paper presents an analytical model, which can predict the impact forces and vibratory response of engine block surface induced by the piston slap of an internal combustion engine. A piston is modelled on a three-degree-of-freedom system to represent its planar motion. When slap occurs, the impact point between piston skirt and cylinder inner wall is modelled on a two-degree-of-freedom vibratory system. The equivalent parameters such as mass, spring constant, and damping constant of piston and cylinder inner wall are estimated by using measured (driving) point mobility. Those parameters are used to calculate the impact force and for estimating the vibration level of engine block surfaces. The predicted results are compared with experimental results to verify the model.     

全光纤调Q掺铒光纤激光器的脉冲研究

报道一种全光纤调Q掺铒光纤激光器,在其结构中采用带有光纤光栅的光纤环形镜作为调Q装置此调Q方案同时具有对腔内损耗进行调制和对激光输出波长选择的功能理论上分析了不同臂长差时的脉冲出现情况,与实验基本相符并对激光单脉冲产生及稳定性进行了分析讨论.     

Ce0.8Sm0.2O1.9的尿素燃烧法合成与性能

采用以尿素为燃料的燃烧合成法制备Ce0.8Sm0.2O1.9(SDC)氧离子导体材料, 对燃烧合成粉体的物相和显微形态进行了表征, 并研究了燃烧法合成SDC的烧结性能以及烧结体的导电性能. 研究结果表明, 采用尿素燃烧法合成SDC具有简便高效和合成粉体烧结活性高的优点. 经过燃烧过程后即可得到立方萤石结构的纯相SDC粉体, 合成粉体的分散性良好, 为50~150 nm的球形颗粒, 具有高的烧结活性, 在1250 ℃的烧结温度下, 陶瓷样品的相对密度可达到95.1%. 在600和800 ℃的测试温度下, 烧结温度为1250 ℃的陶瓷样品的电导率分别达到5.4×10-2和1.0×10-1 Ω-1·cm-1.     

Controllable Ultra Low- k by Via-Typed Air Gap with the Better Design Margin for Logic Devices below 45nm Node

By changing the air gap to a via-typed air gap, the height of the air gap is reduced up to about 50% compared to the height of the trench-typed air gap. The controllable （1 ≤h 〈 2.9） ultra low-k is also easily fabricated by adjusting the space of the via-typed air gap. The via-typed air gap makes the design margin better due to its lower height in the dense and narrow lines.     

Non-Invasive Measurements of Thickness of Superconductor Films by Using Two-Resonant-Mode Rutile Resonator

The film thickness should be known for extrazting the intrinsic surface resistance from the effective surface resistance as measured by using the dielectric resonator method. Thicknesses of 70 nm to 360 nm are measured for YBa2 Cu3 O7-δ films in a non-invasive way by using the two-resonant-mode dielectric resonator （TDR） method. A futile resonator with the respective resonant frequencies of 15.25-15.61 GHz and 15.10-15.37 GHz for the TE021 and the TE012 modes is used for this purpose. Differences between the values as measured by using the TDR technique and those measured by using a step profilometer appear to be less than 3%, which is smaller than the previous value of 5% as measured by using a 8. 6 GHz single-resonance mode futile resonator [Lee et al. J. Korean Phys. Soc. 54（2009）1619]. Merits of using the TDR method are discussed.     

A Characteristic Non-Reflecting Boundary Treatment in Lattice Boltzmann Method

In lattice Boltzmann methods, disturbances develop at the initial stages of the simulation, the decay characteristics depend mainly on boundary treatment methods; open boundary conditions such as equilibrium and bounce-back schemes potentially generate uncontrollable disturbances. Excessive disturbances originate from non-physical reflecting waves at boundaries. Characteristic boundary conditions utilizing the signs of waves at boundaries which suppress these reflecting waves, as well as their implementation in the lattice Boltzmann method, are introduced herein. The performance of our novel boundary treatment method to effectively suppress excessive disturbances is verified by three different numerical experiments.     

A STUDY ON THE VIBRATION CHARACTERISTICS OF A LARGE SIZE KOREAN BELL

Structural elements which determine the vibration and sound properties of the Korean bell are reviewed. Vibration response characteristics under an impact excitation are investigated by the analysis and experiment. Numerical and experimental methods to predict and tune the vibration and sound properties of a large Korean bell (named the New Bosingak Bell) are introduced. Beat phenomenon, which is a very important sound property of the Korean bell, is analytically examined, and an experimental technique to enhance the beat property is proposed.     

MODELLING OF VIBRATING SYSTEMS USING TIME-DOMAIN FINITE ELEMENT METHOD

In this paper, several dynamic systems are modelled using the time-domain finite element method. Galerkin's weak principle is used to model the general second order mechanical system, and is applied to the dynamics of the simple pendulum. Problems that arise during the approximation of the final momentum are also investigated. Furthermore, additional dynamic analysis methods are suggested for hybrid co-ordinate systems that have both slew and flexible modes. The proposed methods are based on both extended Hamilton's principle and Galerkin's weak principle. The matrix wave equation is propagated in a space domain, satisfying the geometric/natural boundary conditions. As a result, the flexible motion can be obtained, and this was compatible with the applied control input. A numerical example is used to demonstrate the effectiveness of the proposed modelling methods for the hybrid co-ordinate systems.     

Investigation of the Interaction Between Sodium （meta） Arsenite and Catechin via ESI Tandem Mass Spectrometry

Catechin,one of the main components of green tea,is considered to have the remedy effect of arsenic poison,although the chemical mechanism is not well known.In this study,sodium(meta)selenite,which is used as herbicide and insecticide as well as rodenticide,was simply mixed with catechin in the CH3OH/H2O(volume ratio 50∶50)solution to investigate the interaction between toxic inorganic arsenic compound and catechin via ESI tandem mass spectrometry.The interaction products of mono-methylated arsenic with catechin in the presence of methanol were identified in the negative mode.Collission induced dissociation(CID)mass spectrometric measurements indicate that monomethylated arsenic was "alkylated" strongly by conjugation at the sites of C2' and C5' in the phenyl ring B of the catechin.The interaction mechanism between sodium(meta)arsenite and catechin was proposed.The results provide useful information to understand the chemical pathway of the detoxification of the arsenic toxicity by catechin.