理论计算中电势能零点的选取对电荷注入的影响

基于紧束缚的Su-Schrieffer-Heeger(SSH)模型,利用非绝热的动力学方法,研究了金属/聚合物结构中电势能零点的选取对电荷注入的影响.理论计算发现,电场越强,电势能零点的选取对电荷注入的影响就越大. 关键词： 电势能 电荷注入 非绝热动力学     

基于线性霍尔传感器的太阳能磁悬浮演示仪

应用电磁学理论、机械力学以及电子技术自制了一套太阳能磁悬浮演示仪,该演示实验仪由太阳能电池供电,利用线性霍尔传感器来探测悬浮物体的位移,以达到控制悬浮的目的,添加数码管电压显示电路,可以定量显示电磁铁的磁性在悬浮过程中随悬浮物位置变化的自动调整,能精确而直观地演示磁悬浮的物理现象该仪器结构简单、性能稳定、操作方便,能广...     

Control of wettability of hydrogenated amorphous carbon thin films by laser-assisted micro- and nanostructuring

A flexible and rapid surface functionalization of amorphous carbon films shows a great potential for various application fields such as biological surfaces and tribological systems. For this purpose, the combination of thin film deposition and subsequent laser material processing was investigated. Amorphous carbon layers doped with hydrogen were deposited on silicon wafers by reactive direct-current magnetron sputtering. Films with three different hydrogen contents were synthesized. Subsequent to the thin film deposition process, UV laser material processing at wavelengths of 193 nm or 248 nm was performed with respect to chemical surface modification and surface structuring on micro- and nanometer scale. Depending on structure size and laser-induced chemical surface modification the adjustment of the surface energy and wetting behaviour in a broad range from hydrophobic to hydrophilic was possible. The chemical modification and the ablation mechanisms near the ablation threshold were strongly influenced by the hydrogen content in amorphous carbon thin films.Structural and chemical information of the as-deposited and modified films was obtained by Raman spectroscopy, X-ray photoelectron spectroscopy and contact angle measurements.     

An effusion-evaporation model for image edge detection

A novel quasi-physical edge detection model is presented. The model, referred to as the effusion-evaporation model (EEM), is inspired by the natural phenomenon that the water effusing from the ground evaporates in the sunshine and leaves a wire like water stain on the ground surface, which reflects the physiognomy of the terrain. Based on the simulation of water effusing and evaporating, an EEM regards the complement of gradient magnitude image as a three-dimensional terrain, and the concave regions, which contain the residual water in the evolution final state, are used to determine the edges. Subjective and objective comparisons are performed on the proposed algorithm and two conventional edge detectors, namely Canny and LoG. The comparison results show that the proposed method outperforms Canny and LoG detectors for the real images and the standard test images with Gaussian noise.     

Theoretical study of new acceptor and donor molecules based on polycyclic aromatic hydrocarbons

Functionalized polycyclic aromatic hydrocarbons (PAHs) are an interesting class of molecules in which the electronic state of the graphene-like hydrocarbon part is tuned by the functional group. Searching for new types of donor and acceptor molecules, a set of new PAHs has recently been investigated experimentally using ultraviolet photoelectron spectroscopy (UPS). In this work, the electronic structure of the PAHs is studied theoretically with the help of B3LYP hybrid density functionals. Using the ΔSCF method, electron binding energies have been determined which affirm, specify and complement the UPS data. Symmetry properties of molecular orbitals are analyzed for a categorization and an estimate of the related signal strength. While σ-like orbitals are difficult to detect in UPS spectra of condensed film, calculation provides a detailed insight into the hidden parts of the electronic structure of donor and acceptor molecules. In addition, a diffuse basis set (6-311++G**) was used to calculate electron affinity and LUMO eigenvalues. The calculated electron affinity (EA) provides a classification of the donor/acceptor properties of the studied molecules. Coronene-hexaone shows a high EA, comparable to TCNQ, which is a well-known classical acceptor. Calculated HOMO-LUMO gaps using the related eigenvalues have a good agreement with the experimental lowest excitation energies. TD-DFT also accurately predicts the measured optical gap.     

Phonon energy in an anharmonic quasi-one-dimensional solid

For the first time, the phonon energy per unit volume in a large anharmonic quasi-one-dimensional solid is determined by considering all polarizations of the various modes of phonon propagation and by assuming the solid as a lattice of atoms behaving as the Morse oscillators. In this context the equilibrium phonon occupation number, which is given by the Bose distribution, replaces formally the vibrational quantum number into the expression for the Morse-oscillator energy. In addition, the quasi-harmonic solid is discussed within the above framework so that the phonon energy per unit volume is calculated for a large quasi-harmonic and quasi-one-dimensional solid.     

Two-dimensional photon counting imaging detector based on a Vernier position sensitive anode readout

A two-dimensional photon counting imaging detector based on a Vernier position sensitive anode is reported. The decode principle and design of a two-dimensional Vernier anode are introduced in detail. A photon counting imaging system was built based on a Vernier anode. The image of very weak optical radiation can be reconstructed by image processing in a period of integration time. The resolution is superior to 100 μm according to the resolution test. The detector may realize the imaging of very weak particle flow of high-energy photons, electrons and ions, so it can be used for high-energy physics, deep space exploration, spectral measurement and bio-luminescence detection.     

轻质建筑中定形相变内隔墙板冬季应用效果研究

现代轻质建筑热容较小,窗墙比较大,冬季在利用透射太阳辐射采暖的同时易造成室内温度波动过大。本文提出将定形相变蓄能板安装在建筑内隔墙表面,以增加建筑热容,减小室温波动。采用经实验验证程序,模拟分析了相变板热物性、表面换热系数和用量对冬季室内温度波动的影响,给出了北京地区相变内隔墙房间的设计原则。     

SOFC/MGT混合系统耦合特性研究

在SOFC/MGT混合分布式能源系统中,选择不同的系统参数将对SOFC乃至SOFC/MGT混合系统的输出特性、安全运行等造成很大的影响。本文建立了一个典型的SOFC/MGT混合系统计算模型,研究了透平入口温度及燃气轮机压比对混合系统性能的影响。结果表明,透平入口温度和压比增大时,系统的输出功率和效率都会下降,而透平入口...