硅和锗纳米线的原子排布和电荷分布的密度泛函紧束缚方法研究

低维硅锗材料是制备纳米电子器件的重要候选材料，是研发高效率、低能耗和超高速新一代纳米电子器件的基础材料之一，有着潜在的应用价值。采用密度泛函紧束缚方法分别对厚度相同、宽度在0.272 nm~0.554 nm之间的硅纳米线和宽度在0.283 nm~0.567 nm之间的锗纳米线的原子排布和电荷分布进行了计算研究。硅、锗纳米线宽度的改变使原子排布，纳米线的原子间键长和键角发生明显改变。纳米线表层结构的改变对各层内的电荷分布产生重要影响。纳米线中各原子的电荷转移量与该原子在表层内的位置相关。纳米线的尺寸和表层内原子排列结构对体系的稳定性产生重要影响。     

Model and nonlinear dynamic analysis of linear guideway subjected to external periodic excitation in five directions

Nonlinear Dynamics - Investigation of the dynamic characteristics of linear guideway is essential for enhancing structural performance of machine tools. However, few mechanical models are...     

In-situ electrochemical study of chalcopyrite pressure oxidation leaching from 110 °C to 150 °C under saturated vapor pressure

Pressure oxidation leaching behavior of chalcopyrite in sulfuric acid solution from 110 °C to 150 °C were investigated by in-situ electrochemical methods. Leaching experiments under saturated vapor pressure conditions were used to simulate the anoxic environment that may be encountered in industrial applications. Scanning electron microscope and X-ray photoelectron spectroscopy were used to characterize the morphology and the chemical status of chalcopyrite surface. Results show that the copper extraction was increased with the increase of leaching temperature. Under the optimal leaching conditions under saturated vapor pressure, the copper and iron extraction are 8.3% and 29.8%, respectively. When the temperature increased from 110 °C to 150 °C, the self-corrosion potential and electrochemical reaction resistance firstly increased and then decreased. In contrast, the resistance of the passive film was always increased with the increase of temperature. The electrochemical study results indicated that the increase in temperature affected the oxidation of chalcopyrite by altering the kinetics of the cathodic reaction and the anodic passivation. Both the self-corrosion current density (i_corr) and rate constant were affected by the reduction of Fe(III). The XPS results show that elemental sulfur and H₃O(Fe₃(SO₄)₂(OH)₆) were the main leaching solid products. The formation of H₃O(Fe₃(SO₄)₂(OH)₆) not only caused a decrease in cathodic reaction kinetics, but also increased the resistance of mass transfer process. Due to the faster release of iron, copper-rich sulphides were formed, which mixed with the elemental sulfur and/or H₃O(Fe₃(SO₄)₂(OH)₆) led to coverage of the chalcopyrite surface.     

Automorphism subgroups for designs with $$\lambda =1$$ λ = 1

Designs, Codes and Cryptography - Given an integer $$k\ge 3$$ and a group G of odd order,  if there exists a 2-(v, k, 1)-design and if v is sufficiently large then there...     

Feature extraction method based on NOFRFs and its application in faulty rotor system with slight misalignment

Nonlinear Dynamics - Fault features extraction method for slight misalignment of rotor systems is researched in this paper. When a rotor system with faults is excited by harmonic inputs, system...     

An efficient numerical method to solve 2-D interval bi-modular problems via orthogonal polynomial expansion

An interval analysis of uncertain bi-modular problems is presented by addressing the efficiency of deterministic solution and reduction of computational cost on the non-linear FE iteration. Firstly, the singularity of 2-D conventional bi-modular constitutive matrix is pointed out via a concise mathematical illustration, and is removed via a complement of shear modulus consistent with the coaxial condition. A new FE model with a full rank constitutive matrix is developed to solve deterministic bi-modular problems, which is well performed in the numerical tests, particularly in term of convergence. Secondly, an orthogonal polynomial expansion based surrogate is constructed to alleviate the heavy computational burden caused by repeated non-linear FE solution in the optimization process for bounds estimation. Numerical examples are given to illustrate the accuracy and efficiency of proposed approach, and a good accordance can be observed between the results obtained by the proposed approach and reference solutions.     

Orientations of graphs avoiding given lists on out-degrees

Let $G$ be a graph and $F:V\left(G\right)\to 2^{\mathbb{N}}$ be a mapping. The graph $G$ is said to be $F$- avoiding if there exists an orientation $O$ of $G$ such that $d_O^{+}\left(v\right)\notin F\left(v\right)$ for every $v\in V\left(G\right)$, where $d_O^{+}\left(v\right)$ denotes the out-degree of $v$ in the directed graph $G$ with respect to $O$. In this paper it is shown that if $G$ is bipartite and $\mid F\left(v\right)\mid \le d_G\left(v\right)/2$ for every $v\in V\left(G\right)$, then $G$ is $F$-avoiding. The bound $\mid F\left(v\right)\mid \le d_G\left(v\right)/2$ is best possible. For every graph $G$, we conjecture that if $\mid F\left(v\right)\mid \le \frac{1}{2}\left(d_G\left(v\right)-1\right)$ for every $v\in V\left(G\right)$, then $G$ is $F$-avoiding. We also argue about this conjecture for the best possibility of the conditions and also show some partial solutions.     

消光式核壳二聚体传感器的设计与光谱特性分析

根据ITO/Au纳米核壳二聚体粒子在生物医学领域的应用合理性,设计了一种实时检测生物液体的核壳二聚体探针消光式传感器;由偶极子理论推导出输出波长与外界环境折射率关系;利用MATLAB设计ITO/Au纳米核壳二聚体粒子结构;采用软件DDSCAT7.3结合离散偶极近似法,利用二聚体有效半径模拟计算了300~950nm可见光到红外光波段不同核壳比、二聚体间距、以及不同介质折射率的消光光谱;根据传感芯片折射率与偶极共振、耦合八级共振的响应关系得出ITO/Au二聚体的折射率灵敏特性。与传统Ag/Au核壳纳米粒子相比,ITO/Au纳米核壳二聚体结构引入了可作为传感芯片灵敏性自参考参数的耦合八级共振峰,同时ITO/Au二聚体结构的折射率灵敏度可达到419nm/RIU。这些工作及其结果对制作消光式传感器具有重要的意义。     

A Lumped Parameter Model of a Fibre-Reinforced Composite Plate with Temperature Dependence Based on Thermal Vibration Measurements

Experimental Mechanics - Background: Experimental modelling techniques are still rare for composite structures under complex thermal environments. Objective: In this paper, by taking a...