燃焰法沉积高品质透明金刚石薄膜的研究

采用燃焰法在大气环境下以30μm/h的较高速率沉积出了均匀、优质、透明的金刚石薄膜.实验结果表明,较高的V(O2)/V(C2H2)和适中的基体温度是获得高品质金刚石薄膜的基本条件;提高反应气体中氧气浓度,可使沉积高品质透明金刚石薄膜的基体温度范围变宽.     

垂直直立石墨烯纳米墙的制备及光热感应

基于等离子体增强化学气相沉积(PECVD)技术,通过调节实验参数,在绝缘衬底玻璃上成功制备出了三维垂直直立的石墨烯纳米墙(GNWs)材料.生长过程中发现石墨烯的质量和尺寸大小与相应的生长时间有关,利用拉曼(Raman)光谱、扫描电子显微镜(SEM)、原子力显微镜(AFM)等仪器对石墨烯纳米墙作了表征.并且,利用石墨烯纳米墙超高的比表面积和优异的散热特性,发现垂直直立的石墨烯纳米片-玻璃杂化混合材料在光热感应上有着良好的响应,将有望促进垂直直立石墨烯纳米片-玻璃杂化的混合材料在透明的太阳热装置和绿色保暖建筑材料上的应用.     

Numerical simulations of sloshing and suppressing sloshing using the optimization technology method

Sloshing is a common phenomenon in nature and industry, and it is important in many fields, such as marine engineering and aerospace engineering. To reduce the sloshing load on the side walls, the topology optimization and optimal control methods are used to design the shape of the board, which is fixed in the middle of the tank. The results show that the new board shape, which is designed via topology optimization, can significantly reduce the sloshing load on the side wall.     

A Simple,Low-cost Method to Fabricate Drag-reducing Coatings on a Macroscopic Model Ship

A low-cost method was used to fabricate superhydrophobic coatings on a macroscopic model ship and the drag-reducing effect was investigated at both low and high speed. Hierarchical structures of the superhydrophobic copper coatings were characterized by means of scanning electron microscopy(SEM) and X-ray diffraction(XRD). Drag coefficient tests on surfaces with different wettability(superhydrophilic, hydrophilic, hydrophobic and superhydrophobic surfaces) showed that the as-prepared superhydrophobic surface exhibited a high remarkable drag reduction of 81% at a low speed of 1 mm/s. In the drag-reducing tests with model ship, the superhydrophobic coatings also exhibited around 16% drag reduction at a velocity of 0.3 m/s.     

One-step Construction of Xanthone Scaffold Assisted by Microwave Irradiation to Optimize the Synthesis of DMXAA

An efficient and concise synthesis of 5,6-dimethylxanthenone-4-acetic acid(DMXAA) was developed. The overall yield of this 3-step procedure was 82%. The key reaction is the one-step construction of xanthone scaffold between 2,5-dibromo-3,4-dimethylbenzoic acid and 2-hydroxyphenyl-acetic acid assisted by microwave irradiation.     

A simple inductor-free memristive circuit with three line equilibria

In this work, a novel inductor-free fourth-order two-memristor-based chaotic circuit is proposed. This new circuit is developed from a current feedback op amp-based sinusoidal oscillator through replacing a linear resistor with a memristor and adding another different parallel memristor to the cascaded memristor–capacitor net. The proposed circuit can perform chaotic, fixed point, and period behaviors. The most striking feature is that this system has three line equilibria and exhibits the extreme multistability phenomenon of the coexisting infinitely many attractors. Specially, amplitude death behavior and transient transition behavior can also be found in the proposed system. By using standard nonlinear analysis tools including system dissipation, equilibrium point stability, phase portrait, Lyapunov exponent spectrum, and bifurcation diagram, the fundamental dynamical characteristics of the circuit are investigated in detail. Moreover, a MULTISIM circuit is designed to verify the numerical simulations.     

Numerical Study on the Dynamics and Oxygen Uptake of Healthy and Malaria-Infected Red Blood Cells

Red blood cells (RBCs) are very important due to their role of oxygen transport from lungs. As the malaria parasite grows in the malaria-infected red blood cells (IRBCs), the properties of the cells change. In the present work, the oxygen uptake by RBCs and IRBCs at the pulmonary capillaries is simulated using a numerical technique based on the two-dimensional immersed interface method. The results for the oxygen uptake by a stationary single RBC have fair agreements with the previously reported results. The numerical results show that the malaria infection could significantly cause deterioration on the oxygen uptake by red blood cells. The results also suggest that the oxygen uptake by individual stationary RBC/IRBC would not be significantly affected by the neighboring cells provided the separation distance is about the dimension of the cell. Furthermore, it appears that the oxygen uptake by both RBCs and IRBCs is dominated by mass diffusion over the convection although the Peclet number is of the order of unity.     

一种二次型忆阻器四阶混沌电路

由HP实验室研制的无源忆阻器得到的荷控二次型忆阻器模型,与有源磁控分段线性和三次光滑忆阻器模型相比,更符合实际.利用此模型并基于蔡氏混沌电路演化而来的拓扑对偶结构设计了一种新型忆阻器四阶混沌电路.理论分析、仿真及电路实现表明,该电路具有依赖于忆阻器初始状态的复杂动力学行为,也会产生随时间和系统参数变化的状态转移等非线性动力学现象,在相轨图中出现"涡眼"和"环眼".     

Comparison about parametric effects on wave propagation characteristics

The frequency effects on the velocities and attenuations of the bulk waves in a saturated porous medium are numerically studied in the cases of considering and neglecting the compressibility of solid grain, respectively. The results show that the whole frequency can be divided into three parts, i.e., low frequency band, medium frequency band, and high frequency band, according to the variation curves and the characteristic frequency. The compressibility of the solid grain affects the P₁ wave distinctively, the S wave tiny, and the P₂ wave little. The effects of the porosity and Poisson's ratio on the bulk waves are numerically analyzed. It is found that both the porosity and Poisson's ratio have obvious effects on the bulk waves. Compared with the results in the case of neglecting the porosity-moduli relation, the results in the case of considering the porosity-moduli relation are more reasonable. The results in the case of considering the porosity-moduli relation can be degenerated into the results of elastic solid and pure fluid, while the results in the case of neglecting the porosity-moduli relation cannot be degenerated into the results of elastic solid and pure fluid. Therefore, the porosity-moduli relation must be considered in the parametric study for a certain porous medium.     

Preparation of In2S3 nanopraricle by ultrasonic dispersion and its tribology property

In this paper, we describe a facile and rapid method for preparing In2S3 nanoparticles via ultrasound dispersion. This method allows us to prepare In2S3 nanoparticles from bulk indium and sulfur with ease and without using expensive agents and in a short time. The possible growing mechanism of the In2S3 nanoparticles was presented. In addition, we provide detailed characterizations including TEM, XRD, TG-DTA, and XPS to study the shape, composition and structure of In2S3 nanoparticles. We also studied the tribology property of In2S3 nanoparticles made using this novel recipe.