Calibration of a single-point laser range finder and a camera

Laser and visual imagery have been broadly utilized in computer vision and mobile robotics applications because these sensors provide complementary information. Since the single-point laser range finder can provide depth information of a single pixel in the observed image, its price and size is very suitable for handheld devices or very lightweight robotic platforms. So the combination of a single-point laser range finder and a camera has become increasingly useful in recent report and industrial applications. In this paper, we propose two accurate calibration methods for determining the position and direction of the laser range finder relative to the camera. Furthermore, we can accomplish calibration even without observing the laser spot in camera image. We evaluate the two methods through experiments which demonstrate their efficiency and high reliability.     

Analytical study of charged boson stars with large scalar self-couplings

We give good approximate analytic solutions for spherical charged boson stars in the large scalar-self-coupling limit in general relativity. We show that if the charge e and mass m of the scalar field nearly satisfy the critical relation \(e^2\approx Gm^2\) (where G is the Newton constant), our analytic expressions for stable solutions agree well with the numerical solutions.     

电子在有机单分子膜中传递研究的新进展

随着分子电子器件研究的兴起,人们广泛使用诸如表面电化学、微接触滴汞电极、导电探针显微术和“Break-junction”等各种电化学或电学手段,对电子传递过程进行了深人研究。本文评述了有关电子在有机单分子膜传递研究的最新进展,同时介绍了与此相关的理论。     

2D SnP3: 具有高载流子迁移率和光吸收率的范德瓦尔斯晶体

本文基于第一性原理计算,预测了二维SnP₃层作为新型半导体材料,具有0.71 eV(单层)和1.03 eV(双层)的间接带隙,这与体结构的金属特性不同. 值得注意的是,2D SnP₃具有9.171×10⁴ cm²?V^-1?s^-1的高空穴迁移率和对于整个可见光谱的高光吸收(∽10⁶ cm^-1),这预示2D SnP₃层有望成为纳米电子学和光电子学的候选材料. 有趣的是,本文发现2D SnP₃双层具有与硅类似的电子和光学特性. 考虑到硅基微电子和光伏技术的巨大成功,本文的研究结果将有助于纳米领域的相关研究.     

A hemicyanine and cucurbit[n]uril inclusion complex: competitive guest binding of cucurbit[7]uril and cucurbit[8]uril

The interaction between the hemicyanine indole derivative H and the cucubit[n]urils Q[7] and Q[8] has been studied using ¹H NMR and UV spectroscopy as well as by fluorescence experiments. Competitive studies on the inclusion of H by Q[7] and Q[8] have also been conducted, and reveal that on changing the size of the Q[n] cavity, the binding behaviour can be very different.     

Hexagonal hollow mesoporous TiO2/carbon composite as an advanced anode material for lithium-ion batteries

Journal of Solid State Electrochemistry - Exploring the fast-charge anodes is crucial to meet the needs of lithium-ion battery (LIB) markets. Here, a hollow hexagonal mesoporous TiO2/carbon...     

Ab Initio Simulation of Ta2O5: A High Symmetry Ground State Phase with Application to Interface Calculation

It is reported that the recently predicted triclinic γ‐phase ground state Ta₂O₅ by Yang and Kawazoe can be assigned a much more symmetric I4₁/amd space group, and is isomorphic to P‐Nb₂O₅. Interestingly, the well‐known high temperature α‐phase Ta₂O₅ also has the I4₁/amd symmetry, but is unstable at zero temperature according to our phonon dispersion calculation. A thorough energy comparison of the β_AL, δ, λ, Β, L_SR, β_R, Pm, Cmmm, γ, and α phases of Ta₂O₅ is carried out using density functional theory under the generalized gradient approximation (GGA). The GGA‐1/2 method is applied in calculating the electronic structure of various phases, where the tetragonal γ‐phase demonstrates a 4.24 eV indirect band gap, close to experimental value. The high symmetry tetragonal phase together with computationally efficient GGA‐1/2 method greatly facilitates the ab initio simulation of Ta₂O₅‐based devices. As an example, the Ohmic contact nature between metal Ta and Ta₂O₅ by calculating an interface model of b.c.c. Ta and tetragonal γ‐Ta₂O₅, using GGA‐1/2 has been explicitly shown.     

Transient evolution of surface roughness on patterned GaAs(001) during homoepitaxial growth

We have investigated the length scale dependence of the transient evolution of surface roughness during homoepitaxial growth on GaAs(100), patterning the surface lithographically with an array of cylindrical pits of systematically varied sizes and spacings. Our atomic force microscopy measurements show that the amplitude of the surface corrugation has nonmonotonic behavior in both the length scale dependence and time evolution. This behavior allows us to rule out a number of existing continuum models of growth.     

Synthesis and thermal stability of gold nanowires within monolithic mesoporous silica

This paper describes the preparation, by a novel and simple method, and the thermal stability of gold nanowires within monolithic mesoporous silica, involving soaking monolithic mesoporous silica in HAuCl₄ aqueous solution, followed by drying and subsequent step-annealing. It has been shown that reduction of Au³⁺ within silica pores can occur during the drying process at 80 °C without any special reduction treatment. After initial annealing at 300 °C, Au nanowires are formed within the pores and are stable at temperatures up to 500 °C. Increasing the annealing temperature leads to a wire-to-rod-to-sphere morphological transformation of the Au nanowires. The surface-mediated reducing groups (-OH) on the silica pore are responsible for the low-temperature reduction of Au³⁺ ions, and the formation of Au nanowires is attributed to the uni-directional diffusion of Au atoms and the confinement of the pore channels. Spheroidization and breaking at some defects in the Au nanowires during annealing at elevated temperature result in the wire-to-rod-to-sphere transformation, accompanied by a blue-shift of the surface plasmon resonance over a very wide region in the optical spectrum. PACS 81.07.-b; 81.40.-z; 81.05.Rm     

Ns strategies: a highly versatile synthetic method for amines

A highly efficient and versatile synthetic method for amines was established using nitrobenzenesulfonamides (Ns-amides) as both a protecting and activating group. The alkylation of N-monosubstituted Ns-amides either proceeded conventionally or under Mitsunobu conditions to provide the N,N-disubstituted sulfonamides, and the Ns group was removed easily with soft nucleophiles via Meisenheimer complexes to give the corresponding secondary amines. The major advantage of this protocol is that both alkylation and deprotection proceed under mild conditions. Thus, with this methodology, the total synthesis of linear and/or macrocyclic natural polyamines can be accomplished efficiently.