Variations in Spectral Slope in Lake Taihu,a Large Subtropical Shallow Lake in China

Spectral slope (S), describing the exponential decrease of the absorption spectrum over a given wavelength range, is an important parameter in the study of of chromophoric dissolved organic matter (CDOM) dynamics, and also an essential input parameter in remote sensing models. Furthermore, S is often used as a proxy for CDOM composition, including the ratio of fulvic to humic acids and molecular weight. The relative broad range in S values reported in the literature can be explained by the different spectral ranges and fitting methods used. A single exponential model is used to fit the S values for 17 investigations involving 458 samples in Lake Taihu from January to October in 2004. The average S value was 15.18 ± 1.39 μm⁻¹ for the range of 280–500 nm, which fell within the range reported in the literature. The frequency distribution of S value basically obeyed a normal distribution. Significant differences in S values between summer and other seasons showed that phytoplankton degradation was one of the important sources of CDOM in summer, whereas CDOM mainly came from the river input in other seasons. Furthermore, the estimated S value decreased with increasing wavelength range used in regression. The maximum and minimum values derived from the regression were 17.89 ± 1.25 μm⁻¹ and 13.62 ± 2.11 μm⁻¹ for the wavelength ranges of 280–380 nm and 400–500 nm, respectively, a decrease of 23.9%. S values significantly decreased with the increase of CDOM absorption coefficients. CDOM absorption coefficients could be more appropriately estimated from exponential model introducing the variation of S with absorption coefficients, making them useful for a remote sensing bio-optical model of Lake Taihu. DOC-specific absorption coefficient a*(λ) and the parameter M describing molecular size of the humic molecules could also be used as a proxy for the sources and types of CDOM. A general relationship was found between S and a*(λ), and M values. S increased with the decrease of DOC-specific absorption coefficient and the increase of M corresponding to the decrease of molecular weight.     

Monte Carlo simulation of hydrogen absorption in palladium and palladium–silver alloys

A modified Monte Carlo (MC) simulation was performed to investigate the hydrogen absorption behavior in Pd and Pd–Ag alloys of the composition Pd_xAg_1−x (x=0.7–0.8) under H₂ pressure (0.1 MPa) at different temperatures. The present method employed can consider the dissociative adsorption of hydrogen molecule and the subsequent absorption of hydrogen atom by formalizing the relationship between the pressure of hydrogen molecule and hydrogen atom. The potential parameters were determined to reproduce the solution enthalpy of hydrogen in pure metals. The results are in good agreement with experimental findings as well as previous theoretical studies. We confirmed that our method is useful to simulate the absorption of hydrogen in metals and alloys.     

Application of the blind source separation method to feature extraction of machine sound signals

As the result of vibration emission in air, a machine sound signal carries important information about the working condition of machinery. But in practice, the sound signal is typically received with a very low signal-to-noise ratio. To obtain features of the original sound signal, uncorrelated sound signals must be removed and the wavelet coefficients related to fault condition must be retrieved. In this paper, the blind source separation technique is used to recover the wavelet coefficients of a monitored source from complex observed signals. Since in the proposed blind source separation (BSS) algorithms it is generally assumed that the number of sources is known, the Gerschgorin disk estimator method is introduced to determine the number of sound sources before applying the BSS method. This method can estimate the number of sound sources under non-Gaussian and non-white noise conditions. Then, the partial singular value analysis method is used to select these significant observations for BSS analysis. This method ensures that signals are separated with the smallest distortion. Afterwards, the time-frequency separation algorithm, converted to a suitable BSS algorithm for the separation of a non-stationary signal, is introduced. The transfer channel between observations and sources and the wavelet coefficients of the source signals can be blindly identified via this algorithm. The reconstructed wavelet coefficients can be used for diagnosis. Finally, the separation results obtained from the observed signals recorded in a semi-anechoic chamber demonstrate the effectiveness of the presented methods .     

Kinetics of oxygen absorption in aqueous sodium dithionite solutions

The absorption and reaction of oxygen in aqueous alkaline solutions of sodium dithionite has been experimentally investigated in a novel gas-liquid contactor. The novel gas-lift bubble column contactor was used to study the kinetics over wide ranges of reactant concentrations, temperature, and pH. The oxygen-sodium dithionite reaction was found to be first-order with respect to dithionite in the range of dithionite concentration < 0.1 M, and second-order in the range of dithionite concentration > 0.1 M. The reaction with respect to oxygen was found to be zero-order for all dithionite concentrations. These results and experimental investigations of the effect of solution alkalinity and temperature on the reaction rate are consistent with previous findings obtained in different gas-liquid contactors. The results thus confirm the feasibility of using the gas-lift bubble column for the kinetics of gas-liquid reactions.     

Dynamic buffering performance of the honeycomb paperboard filled with polyurethane

A new kind of composite buffering material was made by filling the voids of honeycomb paperboard with polyurethane. Drop tests were performed to evaluate the dynamic energy absorption capacity of the material. Based on the tests results, we analyzed the mechanical behaviors of the material under different conditions and obtained the inherent influencing laws of some factors on the material＇s dynamic buffering performance. It was shown that the dynamic buffering performance varied directly with impact velocity, and inversely with the void diameter, thickness and buffeting area of the composite material.     

《中德四季晨昏杂咏》（之八）的译文鉴赏

在诗歌翻译中,译文会因为译者的不同在风格上表现出差异.然而,译文的质量不外乎经受形美、音美和意美的考量.译者应从本国读者的文化背景上结合时代的脉搏来进行“再创造”,做到形式、音律和意蕴的完美统一.歌德的诗歌《中德四季晨昏杂咏》（之八）的四种中文译本各有特色,均在不同程度上实现了“三美”的融合.     

HDTMA改性沸石吸附水中Cr（VI）研究

摘要：研究以阳离子表面活性剂HDTMA改性天然斜发沸石,制得HDTMA改性沸石,进而研究HDTMA改性沸石对废水中Cr（VI）的吸附特征。结果表明：HDTMAL改性沸石对cr（VI）吸附符合Langmuir等温式和拟二级动力学方程,饱和吸附量为10．99mg／g,吸附主要为化学吸附,但温度、pH值和干扰离-~HDTMA沸石吸附cr（VI）具有明显影响。     

Pb(Zr0.52Ti0.48)O3 nanotubes synthesis and infrared absorption properties

Herein a useful methodology to synthesize the lead zirconate titanate (PZT) nanotubes via a dip-coating deposition process with anodic aluminum oxide (AAO) template is proposed. The nano-porous AAO templates were produced using a controlled two-step electrochemical anodization technique. The PZT/AAO composite was formed using the dip-coating wetting technique. The prepared PZT precursor solution was driven into the nanopore channels of AAO template under the driving force of capillary action, subsequently the sintering process of the as-filled templates was carefully tuned to obtain Pb(Zr_0.52Ti_0.48)O₃ nanotubes of crystalline tetragonal phase with uniform pore size and ordered arrange. Fourier transform infrared spectroscopy (FTIR) results show that in the 1200–1900 cm⁻¹ band, the composite structure of PZT/AAO has obvious absorption peaks at 1471.56 cm⁻¹ and 1556.09 cm⁻¹, the absorption intensity of the composite structure is about six times of pure AAO template. The unusual optical properties found in PZT/AAO composite will stimulate further theoretical and experimental interests in ferroelectric nanostructures.     

石墨炉原子吸收测定化探样品中痕量金的研究

采用以王水分解样品,泡沫塑料富集,硫脲解脱,石墨炉原子吸收分光光度计测定微量金。研究了测定时干燥温度和时间的选择,原子化温度和时间的选择,灰化温度和时间的选择,以及王水体积分数对吸附效果等条件对测定结果的影响。该方法检出限为0.2×10-9,经国家一级分析标准样品验证,结果与标准值相符。     

韶冶硫酸系统干吸工序的改造与实践

介绍韶冶Ⅰ硫酸干吸工序技术改造和改造后运行情况．改造后提高了设备生产能力，降低了塔体阻力，改善了有关工艺指标控制，并进一步改善环保排放和节能降耗．