Pose estimation for UAV aerial refueling with serious turbulences based on extended Kalman filter

In recent years, many pose estimation algorithms were developed, and have been successfully applied to solve unmanned aerial vehicle (UAV) aerial refueling pose estimation problems. This paper mainly focuses on solving this problem under serious turbulences circumstance. The extended Kalman filter is a set of mathematical equations to estimate the state of a process, which is able to support estimations of past, present, and even future states. In reference to previous papers and some simulations, we build up the noise models of refueling boom and atmospheric turbulence. Then, an extend Kalman filter is adopted to solve the pose estimation problem in UAV aerial refueling with serious turbulences. The experimental results demonstrate the feasibility and effectiveness of our proposed approach.     

A hybrid Particle Chemical Reaction Optimization for biological image matching based on lateral inhibition

In this paper, a hybrid Particle Chemical Reaction Optimization (PCRO) algorithm and lateral inhibition is proposed to solve the image matching problem. Lateral inhibition has the ability to enhance the characters of image, which can help to improve the accuracy of image matching. In order to overcome the shortcomings of basic Chemical Reaction Optimization (CRO) algorithm, we improve CRO by proposing PCRO which inspired from the thought of Particle Swarm Optimization (PSO). Comparative experimental results in image matching show that our proposed hybrid method performs much better than other bio-inspired algorithms.     

Chaotic biogeography-based optimization approach to target detection in UAV surveillance

This paper describes a novel chaotic biogeography-based optimization (CBBO) algorithm for target detection by means of template matching to meet the request of unmanned aerial vehicle (UAV) surveillance. Template matching has been widely applied in movement tracking and other fields and makes excellent performances in visual navigation. Biogeography-based optimization (BBO) algorithm emerges as a new kind of optimization method on the basis of biogeography concept. The idea of migration and mutation strategy of species in BBO contributes to solving optimization problems. Our work adds chaotic searching strategy into BBO and applies CBBO in template matching. By utilizing chaotic strategy, the population ergodicity and global searching ability are improved, thus avoiding local optimal solutions during evolution. Applying the algorithm to resolving template matching problem overcomes the defects of common image matching. Series of experimental results demonstrate the feasibility and effectiveness of our modified approach over other algorithms in solving template matching problems. Our modified BBO algorithm performs better in terms of convergence property and robustness when compared with basic BBO.     

Colouration mechanism of underglaze copper‐red decoration porcelain (AD 13th–14th century), China

Underglaze copper‐red decoration, i.e. the copper colourant used to paint diversified patterns on the surface of a body and then covered by transparent glaze and fired at high temperature in a reductive firing environment, is famous all over the world. However, the red colouration mechanism generated by underglaze copper remains unclear. In particular, the fact that the edges of the red patterns are orange has been ignored in previous research. Here, non‐destructive analysis has been carried out on a precious fragment of early underglaze red porcelain using synchrotron radiation X‐ray fluorescence, X‐ray absorption near‐edge spectroscopy (XANES) and reflection spectrometry techniques. The results suggest that the copper content in the red region is higher than that in the orange region, and other colour generation elements do not have obvious content difference, indicating that the colour generation effect of the underglaze red product is related to the copper content. XANES analysis shows that the valence states of copper in the red and orange regions are similar and metal copper contributes to their hues. The results of reflection spectrometry demonstrate that tiny orange hues could be attributed to the Mie scatting effect. Therefore, light‐scattering effects should be considered when researching the colouration mechanism of underglaze red.     

Mid-infrared supercontinuum generation in a four-hole As2S5 chalcogenide microstructured optical fiber

We demonstrate the supercontinuum (SC) generation in a four-hole As₂S₅ chalcogenide microstructured optical fiber (MOF) experimentally. The As₂S₅ glass has better property of transmission than As₂S₃ glass in the visible range. The four-hole As₂S₅ MOF is fabricated by a rod-in-tube method. The SCs generated by different pump wavelengths at 2,000, 2,300 and 2,500 nm in the MOF whose length is from 2.3 to 20 cm are demonstrated. Those pump wavelengths correspond to the chromatic dispersion wavelength in the normal chromatic dispersion region, the anomalous chromatic dispersion region close to zero-dispersion wavelength (ZDW) and the anomalous chromatic dispersion region far from ZDW, respectively. Wider SCs can be obtained when pumped at a wavelength in the anomalous dispersion region close to ZDW. The widest SC range of 4,280 nm (from 1,370 to 5,650 nm) covering two octaves was obtained in a 4.8-cm-long fiber pumped at 2,300 nm.     

Photovoltaic effect of TiO2 thick films with an ultrathin BiFeO3 as buffer layer

The photovoltaic (PV) effect of a bilayer anatase TiO₂/BiFeO₃ (BFO) film has been studied. The 20-nm ultrathin BFO layers were deposited on the fluorine-doped tin oxide (FTO) glass substrates by the chemical solution deposition method. An anatase TiO₂ layer is deposited subsequently on the BFO surface via a screen-printing technique. It is found that the FTO/TiO₂/Au cell exhibits negligible PV effect under solar exposure, while the one after introducing an ultrathin BFO film between TiO₂ and FTO leads to a considerable PV effect with an open-circuit voltage of ?0.58 V and a photocurrent density of 18.27 µA/cm². The FTO/BiVO₄ (BVO)/TiO₂/Au cell was constructed to investigate the underlying mechanism for the observed effect. A negligible PV effect of the FTO/BVO/TiO₂/Au cell indicates that the PV effect of the FTO/BFO/TiO₂/Au cell arises mainly from a built-in electric field in the BFO film induced by the self-polarization. Our work opens up a new path to utilize TiO₂ and may influence the future design of solar cells.     

水下通信中的异常声压监控网络系统设计

传统水下通信声压异常监控网络存在无法自主完成节点的投放和回收,存储监控盲区并且无法进行动态组网,不能对异常声压进行准确的监控等较大的缺陷;为此,设计并实现了一种新的水下异常声压监控系统,系统中的通信协议基于节点间的深度信息完成数据的转发,给出了系统中监控器、CC2430 处理器、终端节点以及协调器节点的硬件设计原理并给出了系统采集数据的软件流程;系统中实现了对链路层的AODV 路由协议进行改进,增强系统对异常声压的监控性能;测试结果说明,该系统获取的声压监测星座图明显优于传统系统,在不同的干扰类型下,发射信号使用PSK调制,载波中心频率是10 kHz,采样率是50 kHz,码率是2 000 bit/s;实验结果表明:该种系统具有较低异常声压信号监控误差率,可对异常声压信道的传输特性进行较好的校正和补偿,具有较强稳定性。     

中性及其带电Cun(n=2-12)团簇体系的第一性原理计算研究

结合半经验原子间势及遗传算法,采用密度泛函理论,系统计算研究了Cun(n=2-12)及Cun±(n=2-12)的基态与低激发态的几何结构与电子结构.结果表明：对中性团簇在n=3-6时基态为平面结构,而对于带电体系n=3-5时基态为低维结构,其中平面结构都以三角形为基本单元;对含更多原子的立体结构,基态主要以五角双锥为基本结构单元,传统的高对称性结构在小铜团簇基态中不占优势;计算所得Cun(n=2-12)中性体系结合能与实验结果完全一致,而结合带电体系计算所得团簇电离能与亲和势也与实验相符合;团簇电子结构的相关曲线（电离能、亲和势、二阶差分能）均呈现明显的奇偶振荡现象,这与含偶数电子Cu团簇的相对高稳定性密切相关。     

Size effect of lattice material and minimum weight design

The size effects of microstructure of lattice materials on structural analysis and minimum weight design are studied with extented multiscale finite element method（EMsFEM） in the paper. With the same volume of base material and configuration, the structural displacement and maximum axial stress of micro-rod of lattice structures with different sizes of microstructure are analyzed and compared.It is pointed out that different from the traditional mathematical homogenization method, EMsFEM is suitable for analyzing the structures which is constituted with lattice materials and composed of quantities of finite-sized micro-rods.The minimum weight design of structures composed of lattice material is studied with downscaling calculation of EMsFEM under stress constraints of micro-rods. The optimal design results show that the weight of the structure increases with the decrease of the size of basic sub-unit cells. The paper presents a new approach for analysis and optimization of lattice materials in complex engineering constructions.     

The second harmonic generation in GaAs/GaAlAs spherical quantum dots under Woods-Saxon plus attractive inversely quadratic potential

We examine the profile of second harmonic generation (SHG) for GaAs/GaAlAs spherical quantum dots (QDs) of Woods-Saxon (WS) plus attractive inversely quadratic (AIQ) potential under the joint influence of additional factors (pressure and temperature) and structural parameters (strengths and radius). The energies and wave functions in GaAs/GaAlAs spherical QDs under WS-AIQ limiting potential are calculated using the parametric Nikiforov-Uvarov (NU) method. Depending on the calculated energies and corresponding wave functions, the SHG coefficient is examined by the iterative procedure in the density matrix method for this system. Finally, the calculated results display that a strong SHG coefficient response, and red shift or blue shift energy can be acquired by adjusting parameters.