ZnO纳米带外延树枝状锯齿形缺口结构的制备及其发光特性

应用气固生长方式在没有催化剂的情况下合成出一种新奇的ZnO纳米结构．通过透射电子显微镜分析，发现这种ZnO纳米带外延晶枝直径约20 nm，在[0001]方向有着良好的外延生长取向．提出了一个模型来解释这种树枝状锯齿结构的生长．室温下光致发光测量表明这种ZnO纳米结构在382、491 nm处有一个紫外发光峰和绿光发光峰．     

PLD制备的Cu掺杂SnS薄膜的结构和光学特性

利用脉冲激光沉积(PLD)在玻璃衬底上制备了Cu掺杂SnS薄膜.靶材是由SnS和Cu₂S粉末混合压制而成(Cu和Sn的量比分别为0%、2.5%、5%、7.5%和10%).利用X射线衍射(XRD)、拉曼光谱仪(Raman)、原子力显微镜(AFM)、紫外-可见-近红外分光光度计(UV-Vis-NIR)、Keithley 4200-SCS半导体参数分析仪研究了Cu掺杂量对SnS薄膜的晶体结构、表面形貌、光学性质和电学性能的影响.结果表明:所制备的SnS薄膜样品沿(111)晶面择优取向生长, SnS :5%Cu薄膜的结晶质量最好且具有SnS特征拉曼峰.随着Cu掺杂量的增大, 平均颗粒尺寸逐渐增大.不同Cu掺杂量的薄膜在可见光范围内的吸收系数均为10⁵ cm^-1数 量级.SnS :5%Cu薄膜的禁带宽度E_g为2.23 eV, 光暗电导率比值为2.59.同时, 在玻璃衬底上制备了p-SnS :Cu/n-ZnS 异质结器件, 器件在暗态及光照的条件下均有良好的整流特性, 并具有较弱的光伏特性.     

Experimental investigation of the effect of magnetic field on temperature and temperature profile of diffusion flame using circular grating Talbot interferometer

The effect of magnetic field on temperature and temperature profile of diffusion flame is investigated by using circular grating Talbot interferometer. Talbot interferometric fringes are recorded for diffusion flame generated by butane torch burner, in the absence of magnetic field, in the presence of uniform magnetic field, upward-decreasing and upward-increasing magnetic field. Analysis of recorded interferogram reveals that the temperature of the flame is increased under the influence of the upward-decreasing magnetic field and flame temperature is decreased under the influence of upward-increasing magnetic field. Uniform magnetic field has a negligible effect on temperature of the flame.     

APPLICATION OF PENALTY FUNCTION METHOD IN ISOPARANIETRIC HYBRID FINITE ELEMENT ANALYSIS

IntroductionSince T.H.H.Pain firstly puts forward hybrid element method[1]in1964, the researchand application of hybrid element have got great development. T.H.H.Painet al.havemade important pioneer works in the domain of the research on incompatible displacementstructure hybrid elementstress pattern[2,3]in recentdecades. Reference [4] had provided theoptimizing design concept of hybrid element further and established standardization methodof incompatible displacement structure hybrid eleme…     

润滑脂数据库的数据模型与功能模块设计

在“百科全书”和“坑口电站”的设计思想指导下，规划设计了润滑脂数据库．这种数据库设计有９条查询途径，查询得到有关润滑脂的各种数据、资料和知识；设计有８个功能模块，使数据库具有查询、选用、代用、故障诊断与失效分析、学习、设计计算和维护等功能，因而数据库具有广泛的应用价值     

Electric current measurement using fiber-optic curvature sensor

A novel fiber-optic curvature sensor, which can measure curvature directly, has been developed in recent years. The electric current measurements system based on fiber-optic curvature sensor and electromagnetic principle is developed. A fiber-optic curvature sensor is bonded to a thin-walled cantilever and two circular magnet targets with the same parameters are configured at the tip of the cantilever symmetrically. In this case, the throughput of the sensor will be changed due to the bending deformation of cantilever, which is proportional to the electromagnetic force caused by measured electric current. Direct and alternate characteristics of the proposed measurement system are studied experimentally. The results show that the measurement errors are within the range of ±5.5 mA and the corresponding accuracy is within 1% at the current measurement range from −300 mA to 300 mA, which indicate the feasibility of the proposed measurement system.     

Simultaneous estimation of unwrapped phase and phase derivative from a closed fringe pattern

We propose a new approach for the direct estimation of the unwrapped phase from a single closed fringe pattern. The fringe analysis is performed along a given row/column at a time by approximating the phase with a weighted linear combination of linearly independent basis functions. Gaussian radial basis functions with equally distributed centers and a fixed variance are considered for the phase approximation. A state space model is defined with the weights of the basis functions as the state vector elements. Extended Kalman filter is effectively utilized for the accurate state estimation. A fringe density estimation based criteria is established to select whether the phase estimation is performed in a row by row or column by column manner. In the seed row/column decided based on this criteria, the optimal basis dimension is computed. The proposed method effectively renders itself in the simultaneous estimation of the phase and the phase derivative. The proposed phase modeling approach also allows us to successfully demodulate the low density fringe patterns. Simulation and experimental results validate the practical applicability of the proposed method.     

射频磁控溅射法制备SnS_2薄膜结构和光学特性的研究

采用射频磁控溅射法溅射SnS_2靶,在玻璃基片上以不同射频功率和氩气压强制备一系列薄膜样品,研究了不同工艺条件对薄膜特性的影响。利用X射线衍射(XRD)和拉曼光谱(Raman)对薄膜样品的晶体结构和物相进行表征分析。利用X射线能量色散谱(EDS)、紫外-可见-近红外分光光度计(UV-Vis-NIR)对SnS_2薄膜的化学组分、光学特性等进行测试,计算或分析了SnS_2薄膜样品的组分原子比、光学常数和光学带隙。结果表明:制备SnS_2薄膜的最佳工艺条件为射频功率60 W、氩气压强0.5 Pa。在该条件下,所制备的SnS_2薄膜沿(001)晶面择优取向生长,可见光透过率和折射率较高,消光系数较小,直接带隙为2.81 e V。在此基础上,进一步制备了n-SnS_2/p-Si异质结器件。器件具有良好的整流特性及弱光伏特性,反向光电流随光照强度的增加而增大。器件的光电导机制是由SnS_2禁带中陷阱中心的指数分布所控制。     

Synthesis of barium and strontium carbonate crystals with unusual morphologies using an organic additive

In this paper, strontium carbonate (SrCO₃) and barium carbonate (BaCO₃) crystals were synthesized in the presence of an organic additive-hexamethylenetetramine (HMT) using two CO₂ sources. Scanning electron microscopy and X-ray powder diffractometry were used to characterize the products. The results showed that the morphologies of orthorhombic strontianite SrCO₃ transformed from branch-like to flower-like, and to capsicum-like at last, while the morphologies of BaCO₃ change from fiber-like to branchlike, and to rod-like finally with an increase of the molar ratio HMT/Sr²⁺ and HMT/Ba²⁺ from 0.2 to 10 using ammonium carbonate as CO₂ source. When using diethyl carbonate instead of ammonium carbonate as CO₂ source, SrCO₃ flowers aggregated by rods and BaCO₃ shuttles were formed. The possible formation mechanisms of SrCO₃ and BaCO₃ crystals obtained in different conditions were also discussed.