New Hg2+ and Ag+ selective colorimetric sensor based on thiourea subunits

Anthraquinone derivative (ANNCS) having two thiourea groups was synthesized. ANNCS can selectively sense Hg²⁺ and Ag⁺ through different color change, which was visually discernible by a 58 nm blue shift in the presence of Hg²⁺ and a broadening of the band in the presence of Ag⁺. The recognition mechanism is attributed to the unique structure of anthraquinone attached thiourea group and the interaction between sulfur atom and Hg²⁺ and Ag⁺.     

EXPERIMENTAL AND NUMERICAL STUDY FOR HYDRODYNAMIC CHARACTERISTICS OF AN OSCILLATING HYDROFOIL

The present article reports the experimental Particle Image Velocimetry （PIV） investigation and the corresponding numerical simulation results about the water flow over the oscillating hydrofoil and its unsteady dynamic characters. The experimental study focuses on the effect of mean angles of attack. The comparison between the PIV results and numerical prediction about the flow field using Fluent well demonstrates the capability of CFD on the simulation of the water flow around the pitching hydrofoil. The numerical results indicate that the forced oscillating frequencies have evident effects on the flow separation and vortex shedding. The simulations about the hydrodynamic drag and lift coefficients were also performed.     

Using MPCA of spectra model for fault detection in a hot strip mill

This paper proposes a diagnostic method based on the combination of multi-way principal component analysis (MPCA) and autoregressive (AR) model extraction of power spectrum density. The method is applied to detect one type of surface damage, called pincher, in a China Steel Corporation (CSC) hot strip mill. The time-domain signal is modeled by an autoregressive process because it has less bias and variation. The results of analysis show that the performance of the SPE chart is improved and that 95% of abnormal coils are detected successfully. It is found that MPCA of power spectrum density derived from an autoregressive model has the potential to detect coils with surface damage.     

Automatic Cloud Detection of GF4 Multispectral Imagery Supported by the Priori Terminal Pixel Library

The GaoFen4 (GF4) satellite is China’s first geo-synchronous orbit remote sensing satellite. With the advantages of high frequency and wide width, it can provide fast and stable optical remote sensing images for agricultural, forestry, disaster reduction, meteorology, environmental protection, water conservancy and other applications in China. Efficient image automatic cloud detection helps to further improve the utilization efficiency of GaoFen4 images. CDAG（Cloud Detection Algorihtm-Generating）Cloud detection is an automatic cloud detection algorithm based on spectral analysis of pixel components, which can effectively reduce the influence of mixed pixels, complex surface structure and atmosphere. This paper aims to explore the application of CDAG algorithm in cloud detection of GaoFen4 multispectral imagery (GF4-PMS). Firstly, different cloud types and surface cover types were selected from hyperspectral images (AVIRIS) to establish cloud pixel library and clear sky pixel library. Next, the pixel library of multispectral images was simulated based on Hyperspectral pixel library and spectral response function of GF4-PMS sensor. Then, according to the spectral difference analysis of broken cloud, thin cloud, thick cloud and non-cloud pixel, the similarity probability analysis was performed on the to-be-detected pixel of the GF4-PMS image and the terminal pixel, and the GF4-PMS image cloud detection based on the optimal threshold automatic iteration was realized. Finally, cloud detection accuracy verification was carried out from multiple indicators such as cloud pixel correct rate, clear sky pixel correct rate, false positive rate and missed rate. The results show that AVIRIS images can effectively extract terminal pixel libraries for GF4-PMS image cloud detection. Clouds of Various types on GF4-PMS images can be better identified based on the CDAG algorithm. The accuracy of detection results for broken clouds, thin clouds and thick clouds with different time phases and different underlying surfaces can reach more than 90%. Therefore, the cloud detection method based on the priori terminal pixel library has a good application value for improving the utilization efficiency of GF4-PMS images.     

Experiments in a large-scale venturi scrubber: Part I: Pressure drop

The present work details pressure drop measurements in a large-scale venturi scrubber with an inlet and throat diameters of 250 and 122.5 mm, respectively.The flow rates were varied between 0.4835 and 0.987 kg/s for the gas while the liquid was set between 0.013 and 0.075 kg/s. The results show that the pressure drop depends on both the gas and liquid phases flow rates, the droplet fraction and the method of liquid injection (spray and film).The pressure drop in the diverging section is well predicted by a boundary layer model.     

地下开挖中边界处位移计算的粘弹性分析

本文首先利用弹性理论按空间问题解得地下水平巷道端面最大位移解，然后得用拉氏变换法按Maxwell本构方程解得粘弹性解，从而考虑了地下开挖位移计算中的时间效应。     

Investigation into Photocatalytic Degradation of Gaseous Benzene in a Circulated Photocatalytic Reactor (CPCR)

Due to the fact that suspended TiO₂ powder enjoys free contact with gaseous pollutant molecules in photocatalytic reactors, it can generally achieve better efficiency than immobilized TiO₂ catalysts. However, difficulties with the separation of this catalyst powder from treated pollutants and its re‐use often limit its application. Therefore, a circulated photocatalytic reactor (CPCR) was designed to enhance the performance of the photocatalytic degradation of gaseous benzene. TiO₂ film photocatalysts were prepared by the sol‐gel method at low temperatures and coated onto the inner wall of this reactor by a bonding agent composed of poly‐(2, 2‐dimethyl)‐acrylic ethylene ester emulsion in which TiO₂ powder was characterized by FTIR, TEM and SEM. In particular, the influences of initial concentration and gas flow rate of benzene on the degradation conversion, D_p, apparent reaction rate constants, k_r, initial degradation rate, r, and the deactivation and regeneration of catalyst in the CPCR, were investigated. The results indicated that the degradation conversion, apparent reaction rate constants and initial degradation rate were closely correlated to the initial concentration of benzene. To elucidate the factors governing the observations, the adsorption characteristics and kinetics of the photocatalytic degradation of benzene were analyzed using the Langmuir adsorption isotherm and Langmuir‐Hinshelwood kinetic model. It was found that the reaction kinetics were best described by a fixed pseudo‐first‐order kinetic equation of photocatalytic degradation of gaseous benzene in the CPCR.     

Effect of surfactant on depressing the hydrolysis process for aluminum nitride powder

The hydrophobic treatment of AlN powders is commonly used for depressing their hydrolysis process. A commercially claimed water-resistant AlN powder (hydrophobic treated) was investigated through hydrolysis with pH measurements of the suspensions. For comparison, an untreated AlN powder was studied with similar hydrolysis condition. The water-contacted powders were subsequently analyzed with XRD. Both pH measurements and XRD results indicated that the water-resistant AlN powders were not resistant to hydrolysis without surfactant addition. It was also found that the surfactant was effective in depressing hydrolysis of the hydrophobic treated AlN powders, but slowed down slightly the hydrolysis process for untreated AlN powders. A critical surfactant concentration of 0.7 wt.% was required for successfully depressing the hydrolysis process.     

氨噻肟酸与AE-活性酯合成的研究进展

综述了生产氨噻肟酸的几种方法,并对各种方法的特点、存在的问题进行了分析,提出部分步骤采用超临界CO2作为反应体系。总结了工业上用氨噻肟酸和二硫化二苯并噻唑生产AE-活性酯的方法,提出用氨噻肟酸直接与硫醇基苯并噻唑合成AE-活性酯的方法,并从理论上研究其可行性,阐述了用氨噻肟酸直接与硫醇基苯并噻唑合成AE-活性酯的指导性意义。     

Influence of the dissolved oxygen content on corrosion of the ferritic–martensitic steel P92 in supercritical water

The corrosion of the ferritic–martensitic steel P92 exposed to supercritical water at 550 °C under 25 MPa with the dissolved oxygen contents of 100, 300 and 2000 ppb was investigated. The results indicated that the weight gain increased with the dissolved oxygen content. The oxide scale with a typical dual-layered structure including a Fe-rich outer magnetite layer and a Cr-rich inner layer was formed on all samples in spite of different dissolved oxygen. Finally, the possible explanations for the influence of the dissolved oxygen content on the weight gain and exfoliation of oxide scale were given.