A new wavelet transform for reliability-guided phase unwrapping of optical fringe patterns

A new daughter wavelet definition for reliability-guided phase unwrapping of the optical fringe pattern is introduced. The new daughter wavelet definition is given by normalized mother wavelet with a new factor including a Gaussian function. The modulus of the wavelet transform coefficients, obtained by using daughter wavelet under this new daughter wavelet definition, includes not only modulation information but also local frequency information of the deformed fringe pattern. Therefore, it can be treated as a good parameter which represents the reliability of the reconstructed phase data. Mathematical demonstration of this parameter is given. Both the computer simulation and experiment reveal the validity of the proposed method.     

掺杂聚合物蓝光发光二极管

报道了用有机染料ＴＰＢ（１，ｌ，４，４－四苯基丁二烯）分散到ＰＶＫ（聚乙烯基咔唑）中的掺杂聚合物作有源层制作的蓝光发光二极管及其发光特性。聚合物发光层用旋转涂敷的方法制备，用透明导电材料ＩＴＯ（铟锡氧化物）、金属Ａｌ作为正负电极。器件正向偏压为１３Ｖ时，可以看到蓝光发射，峰值波长为４５５ｎｍ，注入电流为５０ｍＡ／ｃｍ２时，亮度为４４ｃｄ／ｍ２。     

Mobile Rayleigh Doppler wind lidar based on double-edge technique

<正>We describe a mobile molecular Doppler wind lidar(DWL) based on double-edge technique for wind measurement of altitudes ranging from 10 to 40 km.A triple Fabry-Perot etalon is employed as a frequency discriminator to determine the Doppler shift proportional to the wind velocity.The lidar operates at 355 nm with a 45-cm-aperture telescope and a matching azimuth-over-elevation scanner that provides full hemispherical pointing.To guarantee wind accuracy,a single servo loop is used to monitor the outgoing laser frequency to remove inaccuracies due to the frequency drift of the laser or the etalon.The standard deviation of the outgoing laser frequency drift is 6.18 MHz and the corresponding velocity error is 1.11 m/s.The wind profiles measured by the DWL are in good agreement with the results of the wind profile radar(WPR).Evaluation is achieved by comparing at altitudes from 2 to 8 km.The relative error of horizontal wind speed is from 0.8 to 1.8 m/s in the compared ranges.The wind accuracy is less than 6 m/s at 40 km and 3 m/s at 10 km.     

Efficient single-layer electroluminescent device based on a bipolar emitting boron-containing material

A novel multifunctional 1,6-bis(2-hydroxyphenyl)pyridine boron bis(4-n-butyl-phenyl)phenyleneamine compound in which the hole-transporting (HT), electron-transporting (ET), and emitting (EM) components are integrated into a single molecule was synthesized and used as an emitting material to fabricate an efficient single-layer electroluminescent device.     

Fourier transform profilometry based on a fringe pattern with two frequency components

A modified Fourier transform profilometry (FTP) based on a fringe pattern with two frequency components is proposed, which provides a larger measuring range than that of the traditional FTP. We analyze the maximum measuring range and give an expression to describe the measurable slope of the height variation limitation of this method. The modified FTP provides us another approach to eliminate frequency overlapping. When the spectra distribution of a measured object is not spherical symmetry, we can avoid the frequency aliasing through projecting a fringe pattern with two frequency components, instead of increasing the density of the projected fringe and the resolution of a CCD camera. The theoretical analysis and primary experiments verified the method.     

Crystal structures of silicon-rich lithium silicides at high pressure

Silicon (Si) is one of the most essential elements, as it is indispensable for modern electronic technology. The standard Si structure at ambient conditions is the cubic diamond structure, and it has an indirect band gap, which prevents it from being considered as a next-generation platform for semiconductor technologies. Therefore, the search for new allotropes of silicon has attracted great attention. Herein, first principles swarm-intelligence structure searches coupled with density-functional theory were performed to explore the stable high-pressure phases of silicon-rich lithium containing compounds, LiSi_x ($x=4\text{–}8$). The LiSi₄ stoichiometry was predicted to be stable, and it was found to assume one of the following space groups, P4/mnc, Cmmm, and C2/m within the pressure range of 0 to 50 GPa. By removing the Li atoms from these compounds, three silicon allotropes were obtained that were metastable at ambient pressures. Our work illustrates how novel silicon allotropes can be predicted using the CALYPSO method.     

Supermolecule density functional calculations on the water exchange of aquated Al(III) species in aqueous solution

Supermolecule density functional calculations suggest the dissociative (D) mechanism for the water exchange of aquated Al(iii) species in aqueous solution and the calculated results agree well with experimental data.     

Exfoliated Pt-clay/Nafion nanocomposite membrane for self-humidifying polymer electrolyte fuel cells

Monolayers of Pt nanoparticles of diameters of 2-3 nm with a high crystallinity were successfully anchored onto exfoliated nanoclay surfaces using a novel chemical vapor deposition process. Chemical bonding of Pt to the oxygen on the clay surface ensured the stability of the Pt nanoparticles, and hence, no leaching of Pt particles was observed after a prolonged ultrasonication and a rigorous mechanical agitation of Pt-clay in the Nafion solution during the membrane casting process. Systematic analysis using WAXD and TEM showed that the recasting process produced a new self-humidifying exfoliated Pt-clay/Nafion nanocomposite membrane with a high crystallinity and proton conductivity. In situ water production for humidification of the dry membranes without any external humidification was characterized by a combined water uptake and FTIR analysis of the as-prepared membrane after a single cell testing without using electrodes. The power density at 0.5 V of a single cell made of a Pt-clay/Nafion nanocomposite membrane was 723 mW/cm2, which is 170% higher than that made of a commercial Nafion 112 membrane of similar thickness. No compromise in mechanical properties was observed.     

Homochiral organic molecular cage RCC3-R-modified silica as a new multimodal and multifunctional stationary phase for high-performance liquid chromatography

In this work, homochiral reduced imine cage was covalently bonded to the surface of the silica to prepare a novel high-performance liquid chromatography stationary phase, which was applied for the multiple separation modes such as normal phase, reversed-phase, ion exchange, and hydrophilic interaction chromatography. The successful preparation of the homochiral reduced imine cage bonded silica stationary phase was confirmed by performing a series of methods including X-ray photoelectron spectroscopy, thermogravimetric analysis, and infrared spectroscopy. From the extracted results of the chiral resolution in normal phase and reversed-phase modes, it was demonstrated that seven chiral compounds were successfully separated, among which the resolution of 1-phenylethanol reached the value of 3.97. Moreover, the multifunctional chromatographic performance of the new molecular cage stationary phase was systematically investigated in the modes of reversed-phase, ion exchange, and hydrophilic interaction chromatography for the separation and analysis of a total of 59 compounds in eight classes. This work demonstrated that the homochiral reduced imine cage not only achieved multiseparation modes and multiseparation functions performance with high stability, but also expanded the application of the organic molecular cage in the field of liquid chromatography.     

Theoretical insight into the enhanced CH4 desorption via H2O adsorption on different rank coal surfaces

The density functional theory was used to investigate the adsorption of CH₄ and H₂O on different rank coal surfaces.The coal rank is the dominant factor in affecting the adsorption capacity of coal.In order to better understand gas and water interaction with coal of different maturity,we developed fourteen coal models to represent the different rank coal.The interactions of CH₄ and H₂O with coal surfaces were studied and characterized by their adsorption energies,Mulliken charges and electrostatic potential surfaces.The results revealed that the interaction between coal and CH₄ was weak physical adsorption,and that the interaction between coal and H₂ O consisted of physical and chemical adsorption.Adsorption energy of coal–H₂O system was larger than that of coal–CH₄ on all rank coals,suggesting that the adsorption priority in the coal models is H₂ O > CH₄.Consequently,the injection of H₂ O into the different rank coal could effectively enhance the coal bed methane（CBM） recovery.