醇类化合物热值改进剂结构和性质的理论研究

采用Materials Studio8.0软件中的DMol3程序对醇类化合物热值改进剂的几何结构和性质(振动频率、反应活性、热力学及稳定性)进行了理论研究,得到了分子稳定的几何构型、各原子上的电荷分布、热力学性质、Fukui指数和前沿分子轨道能级.计算结果表明:醇类化合物热值改进剂分子结构中的1个-OH是影响其抗氧化活性的主要部位和亲电反应发生的活性位点,整体表现为比较理想的稳定性能.     

Spatiotemporal multiple coherence resonances and calcium waves in a coupled hepatocyte system

Spatiotemporal multiple coherence resonances for calcium activities induced by weak Gaussian white noise in coupled hepatocytes are studied. It is shown that bi-resonances in hepatocytes are induced by the interplay and competition between noise and coupling of cells, in other words, the cell in network can be excited either by noise or by its neighbour via gap junction which can transfer calcium ions between cells. Furthermore, the intercellular annular calcium waves induced by noise are observed, in which the wave length decreases with noise intensity augmenting but increases monotonically with coupling strength increasing. And for a fixed noise level, there is an optimal coupling strength that makes the coherence resonance reach maximum.     

低冲击下固体推进剂延迟起爆现象

为了研究固体推进剂在低强度冲击作用下的延迟爆轰现象（XDT）,设计了2次冲击波加载的双隔板实验。用X光摄像技术观测了推进剂在低强度冲击作用下的延迟起爆现象。建立了推进剂双隔板实验计算模型,运用非线性动力学有限元方法对推进剂的双隔板实验进行了数值模拟,得到推进剂在2次独立冲击波加载作用下的压力历史,分析了推进剂发生延迟爆轰的受力过程。结果表明,在强度较低的冲击波作用下,该推进剂会发生XDT现象,对推进剂重复冲击加载作用和推进剂在加载作用下的敏化程度是控制XDT现象发生的主要因素。     

Spectroscopic Investigations of Phase-Separated Thermotropic Layers Based on UV Cured Acrylate Resins

Summary: In this paper spectroscopic techniques were adapted and applied to characterize the optical and morphological properties of thermotropic resins. Thermotropic films were prepared by variation of resin base and thermotropic additives. By UV/Vis/NIR spectroscopy the solar optical properties, the switching temperature, the switching process and the residual transmittance in the opaque state were determined. To control the sample temperature from ambient to 100 °C a conventional UV/Vis/NIR spectrophotometer equipped with an Ulbricht-sphere was adapted by a heating stage. Additive content, distribution and scattering domain size were characterized by Differential Scanning Calorimetry, Attenuated Total Reflectance spectroscopy and microscopic techniques. For the investigated film types hemispheric solar transmittance values ranging from 80 to 87% and 75 to 85% were obtained in the clear and the scattering state, respectively. The diffuse solar transmittance values increased significantly from 14 to 40% below the switching temperature to 36 to 70% at elevated temperatures. The thermotropic resins exhibit a steep and rapid switching process with switching temperatures between 45 and 70 °C. The materials with the best switching properties are characterized by distinct differences in refractive index between the components, a uniform additive distribution and scattering domains with diameters below 1000 nm.     

浓硫酸催化合成环烷酸正丁酯

以新疆克拉玛依的大分子环烷酸为原料,在浓硫酸的催化下,与正丁醇反应,制备了环烷酸正丁酯.探讨了带水剂用量、反应时间、反应温度、催化剂用量、酸醇摩尔比对酯化反应的影响.得出了最佳工艺条件:苯用量为50%,反应时间为4 h,反应温度为160℃,浓硫酸质量分数为115%,酸醇摩尔比为1∶2时,环烷酸的酯化率高达92%.     

Output frequency properties of nonlinear systems

Nonlinear systems usually have complicated output frequencies. For the class of Volterra systems, some interesting properties of the output frequencies are studied in this paper. These properties show theoretically the periodicity of the output super-harmonic and inter-modulation frequencies and clearly demonstrate the mechanism of the interaction between different output harmonics incurred by different input nonlinearities in system output spectrum. These new results have significance in the analysis and design of nonlinear systems and nonlinear filters in order to achieve a specific output spectrum in a desired frequency band by taking advantage of nonlinearities. Examples and discussions are given to illustrate these new results.     

Interfacial stress transfer behavior in a specially-shaped fiber/matrix pullout test

Specially designed fibers are widely used in engineering practice because the specially-designed shape can help to improve the bonding strength of the fiber and the interface. Studied in this paper is the interfacial shear stress transfer behavior on both sides of the specially designed fiber when it is being pulled out; in which automatic analysis of three-dimensional photoelasticity is employed and the finite element method is adopted. The results show that the stress transfer occurs mainly in the region near the fiber＇s embedded end where the stress reaches its critical point, leading to debonding of the interface. Before debonding, as the pullout loading increases, the peak value of shear stress transfers along the fiber from the embedded end to the interior of the matrix, and then stops at the hooked part of the fiber because of its impediment. When the interface begins to debond as the load increases, the shear stress can be transferred to the hooked part.     

采用纳米晶柱阵列衬底抑制失配位错形成的分子动力学模拟研究

运用分子动力学方法对纳米晶柱阵列衬底上铝簿膜的外延生长进行了模拟研究.所采用的原子间相互作用势为嵌入原子法(EAM)多体势.模拟结果表明：采用纳米晶柱阵列衬底可以在不形成失配位错的条件下释放其上生长的外延薄膜晶体中的失配应变,有效地抑制其中失配位错的形成,获得高质量的外延薄膜晶体;这种纳米晶柱阵列的几何设计应满足两个基本条件：1) 晶柱的横截面尺寸应大于对应温度下的晶柱热失稳临界尺寸,以克服纳米结构的热失稳,模拟显示700K下铝的热失稳临界尺寸为19nm;2) 晶柱的高度与间距之比应大于076,以保证 关键词： 失配位错 分子动力学 纳米晶柱 铝     

自均衡线性相位高温超导滤波器的设计

针对第三代移动通信CDMA 2000标准用超导滤波器的技术要求,设计了一种自均衡线性相位高温超导滤波器,给出了14阶三个交叉耦合的CQ结构滤波器理论计算结果、等效电路、耦合矩阵,设计的滤波器中心频率为830MHz,65%带宽内的群时延波动优于±10ns,滤波器模拟仿真结果与理论计算很好得吻合。     

Polarization shifting interferometric profilometer

A phase sensitive Michelson interferometer based on interference microscope configuration with a polarization adjustment approach is proposed to determine the two-dimensional (2-D) surface profile of optical grating with real time capability. In the proposed method, nonlinear behavior of a PZT phase shifter is avoided by use of polarization stepping and a phase map is developed with the four-bucket algorithm. The phase map is unwrapped to give the true surface profile of the sample. A close agreement of measurements is found between the measured result determined by the proposed method and that determined by an atomic force microscope (AFM). We also analyzed the estimated uncertainty of measurement in the nanometer range for the random fluctuations of the experimental parameters.