超导电子学的若干应用及展望

介绍了超导电子学的一系列特性,评述超导在弱电方面的主要研究、应用领域及成果以及国内外发展现况。     

Light‐Emitting Silicon Nanocrystals from Laser Pyrolysis

Crystalline Si nanoparticles with diameters between 2.5 and 20 nm are prepared by CO₂‐laser‐induced decomposition of silane in a gas flow reactor. A small portion of the products created in the reaction zone is extracted through a nozzle into a high‐acuum apparatus to form a freely propagating molecular beam of clusters and nanoparticles that can be deposited on suitable substrates. The strong visible photoluminescence (PL) of the Si nanocrystals is studied as a function of their size, and as a function of the time for which they are exposed to air. All observations can be explained on the basis of quantum confinement as the only origin of the PL. Chemical methods are exploited to modify the surface of the Si nanoparticles and to reduce their size, thus shifting their PL to shorter wavelengths. With this technique, the Si nanoparticles, collected in much larger quantities in the filter of the flow reactor, can be made strongly luminescent so that they may be used for various applications.     

RLC介观电路中的广义动量和动力学动量

用幺正变换的方法，求出了RLC介观电路中的广义坐标与广义动量、动力学坐标与动力学动量的测不准关系，从而发现前者与时间无关，后者与时间成指数关系。     

Fabrication of CdS quantum dot sensitized solar cells via a pressing route

CdS quantum dots have been self-assembled on the surface of dispersed nanocrystalline TiO₂ particles, and a light-harvesting electrode has been fabricated from the resulting sensitized P25 particles using the pressing route. The spectroscopic and photochemical properties of photosensitized nanocrystalline TiO₂ electrodes were studied. The results indicate that electrode preparation by the pressing route may lead to partial loss or damage of the CdS coating and creation of regions that are inaccessible to the redox electrolyte. Nevertheless, the pressing method using pre-coated powders shows promise as a low cost method for the preparation of photoelectrodes in sensitized-solar cells.     

LONWORKS与RS-232的互连适配器的设计开发

Lonworks技术中的核心是神经元芯片，本详述了神经元芯片的一种I/O应用模式-并行口I/O模式，并介绍了基于此I/O模式设计开发的Lonworks协议与RS-32标准转换的互连适配器。     

Structural Effects in the Electrodeposition of CdSe Quantum Dots on Mechanically Strained Gold

CdSe nanoparticles were electrodeposited on mechanically strained gold, the latter achieved by controlled bending of gold films evaporated on mica. It is shown that the size and bandgap of the electrodeposited CdSe quantum dots (QDs) can be varied by applying mechanical strain to the Au substrate during deposition. This is attributed to change in the lattice spacing of the strained {111} Au and consequently in the lattice mismatch between the Au and the CdSe. Negative mechanical strain promotes the formation of rocksalt (RS) CdSe nanocrystals, normally existing only at high pressures. This is attributed to surface tension compression in the small crystals, together with enhancement of the phase transition by the CdSe/substrate interface.     

压缩真空场中量子存储单元的消相干特性

两能级原子作为量子存储单元，当存储单元置于压缩真空库（人工制备的库）时，利用存储单元约化密度算符非对角元的时间演化，研究单光子过程和工双光子过程中存储单元的消相干特性。在压缩真空库中，可以消除量子存储单元的消相干。     

神经元学习控制在交流伺服系统中的应用

对交流永磁同步电机伺服系统提出一种单个神经元自学习型速度调节器，仿真结果表明该控制器具有一定的自适应能力，结构简单，易于数字实现．     

Many electron effects in semiconductor quantum dots

Semiconductor quantum dots (QDs) exhibit shell structures, very similar to atoms. Termed as ’artificial atoms’ by some, they are much larger (1 100 nm) than real atoms. One can study a variety of manyelectron effects in them, which are otherwise difficult to observe in a real atom. We have treated these effects within the local density approximation (LDA) and the Harbola-Sahni (HS) scheme. HS is free of the self-interaction error of the LDA. Our calculations have been performed in a three-dimensional quantum dot. We have carried out a study of the size and shape dependence of the level spacing. Scaling laws for the Hubbard ‘U’ are established.     

An efficient and accurate quantum lattice-gas model for the many-body Schrödinger wave equation

Presented is quantum lattice-gas model for simulating the time-dependent evolution of a many-body quantum mechanical system of particles governed by the non-relativistic Schrödinger wave equation with an external scalar potential. A variety of computational demonstrations are given where the numerical predictions are compared with exact analytical solutions. In all cases, the model results accurately agree with the analytical predictions and we show that the model's error is second order in the temporal discretization and fourth order in the spatial discretization. The difficult problem of simulating a system of fermionic particles is also treated and a general computational formulation of this problem is given. For pedagogical purposes, the two-particle case is presented and the numerical dispersion of the simulated wave packets is compared with the analytical solutions.