Effect of temperature on the interactions between cellulose and lignin via molecular dynamics simulations

Cellulose - Heating is essential in various biomass pre-treatments and thermal conversion processes. It is of practical significance to study the characteristics of cellulose-lignin and...     

Fluid‐structure coupling of linear elastic model with compressible flow models

Cavitation erosion is caused in solids exposed to strong pressure waves developing in an adjacent fluid field. The knowledge of the transient distribution of stresses in the solid is important to understand the cause of damaging by comparisons with breaking points of the material. The modeling of this problem requires the coupling of the models for the fluid and the solid. For this purpose, we use a strategy based on the solution of coupled Riemann problems that has been originally developed for the coupling of 2 fluids. This concept is exemplified for the coupling of a linear elastic structure with an ideal gas. The coupling procedure relies on the solution of a nonlinear equation. Existence and uniqueness of the solution is proven. The coupling conditions are validated by means of quasi‐1D problems for which an explicit solution can be determined. For a more realistic scenario, a 2D application is considered where in a compressible single fluid, a hot gas bubble at low pressure collapses in a cold gas at high pressure near an adjacent structure.     

Terahertz radiation from pentacene organic diode at room temperature

We investigate terahertz radiation(T-rays) from a pentacene organic diode at room temperature. The quantum chemistry calculation for frequency-related Huang–Rhys factor of pentacene is also carried out. The results demonstrate that the T-rays can come from a bending vibration of pentacene skeleton after the energy of pentacene exciton transferring to the vibrational excited state via electron–phonon coupling. Frequency and natural bond orbital analytics of pentacene and its derivatives are performed in order to explain the result and develop new materials to get higher emission. This work provides a new way to produce T-rays with a simple device at room temperature.     

Spatially modulated polarimetry based on a vortex retarder and Fourier analysis

We report a spatially modulated polarimetry scheme by using a zero-order vortex half-wave retarder(ZVHR)and a spatial Fourier analysis method.A ZVHR is employed to analyze the input polarized light and convert it into a vectorial optical field,and an analyzer is set after the ZVHR to form an hourglass intensity pattern due to the spatial polarization modulation.Then,the input light’s Stokes parameters can be calculated by spatial Fourier analysis of the hourglass pattern with a single shot.The working principle of the polarimeter has been analyzed by the Stokes-Mueller formalism,and some quantitative measuring experiments of different polarization states have been demonstrated.The experimental results indicate that the proposed polarimeter is accurate,robust,and simple to use.     

Portfolio Selection and Risk Control for an Insurer With Uncertain Time Horizon and Partial Information in an Anticipating Environment

Methodology and Computing in Applied Probability - This paper is devoted to the study of an optimal investment and risk control problem for an insurer. The risky asset process and the insurance...     

A new solution of reducing polymer optical fiber losses

Polymethyl methacrylate (PMMA) is one of the most commonly used optical materials. However, the application of it in the area of optical communication is strongly limited by the intrinsic absorption loss of carbon-hydrogen stretching vibration. In this paper, we present a method to solve the problem by adopting the hollow-core fibers with cobweb cladding structure. The fibers use a single dielectric material and may solve the problem of structural support. Thus the feasibility of the “OmniGuide” fibers is improved, while a series of advantages of the “OmniGuide” hollow-core fiber are retained. It is promising that a fiber with low transmission loss, high bandwidth, large-core, and low costs can be designed and fabricated using PMMA. At the same time, a very broad range of the wavelengths (from visible to near infrared region, for instance, wavelengths at 0.65-1.12 μm, and even 1.30 μm, 1.54 μm and their neighbors) may be adopted for signal wavelength.     

空心阴极灯激发的微波等离子体炬原子/离子荧光光谱研究--钙的原子/离子荧光光谱

用强短脉冲供电技术的空心阴极灯作激发源、微波等离子体炬作原子／离子化器，建立了原子／离子荧光光谱实验装置。详细研究了微波等离子体功率、观察高度、空心阴极灯电流等因素对原子／离子荧光信号强度的影响，测量了系统对Ca的原子／离子荧光光谱的检出限。     

空间遥感相机长条反射镜组件的动力学特性分析

空间遥感相机长条反射镜较圆反射镜的整体刚度相差很大,整个组件在随火箭发射过程中因力学环境引起的自身位置改变导致面形的微小畸变从而对成像质量造成严重影响。因此,反射镜组件的设计就成为整个相机系统研制的重点与难点之一。对其进行科学、严谨的力学环境仿真是设计中的有效辅助手段。对某相机的长条反射镜组件动力学响应进行了较为深入的研究,借助MSC-patran,用有限元法进行了求解。获得了组件的动力学特性。     

介质加载环板慢波结构高频特性研究

 提出了一种适用于环板结构的计算等效相对介电常数的方法，利用变分法导出了介质加载环板慢波结构的色散方程和耦合阻抗表达式。计算结果表明，介质加载能够有效降低环板慢波结构的工作电压。计算结果与CST-MWS的模拟结果吻合良好，说明所提出的计算等效相对介电常数的方法和计算色散方程的方法对环板慢波结构是切实可行的。     

Von Neumann Entropy of an Electron in One-Dimensional Determined Potentials

By using the measure of von Neumann entropy, we numerically investigate quantum entanglement of an electron moving in the one-dimensional Harper model and in the one-dimensional slowly varying potential model. The delocalized and localized eigenstates can be distinguished by von Neumann entropy of the individual eigenstates.There are drastic decreases in von Neumann entropy of the individual eigenstates at mobility edges. In the curve of the spectrum averaged von Neumann entropy as a function of potential parameter λ, a sharp transition exists at the metal-insulator transition point λc = 2. It is found that the von Neumann entropy is a good quantity to reflect localization and metal-insulator transition.