甲玛地区角岩矿微生物浸出的试验研究

介绍了西藏华泰龙矿业开发有限公司角岩的矿石性质,针对该低品位铜矿石进行了详细的微生物浸出试验研究,在原矿铜品位仅为0.12%、SiO_2含量高达69.12%的情况下,用接种量为10%的浸矿菌液,浸出1 d时,铜浸出率即为34.44%,浸出11 d时,浸出率达到70.02%,此时较无菌条件下的浸出率高出17.46个百分点。     

基于SnO2中空纳米球的低温氢气传感器的研究

采用水热法一步合成SnO2纳米材料,采用XRD、SEM、TEM和氮吸附-脱附对材料的结构和形貌进行表征。表征结果表明所制备SnO2纳米材料是由直径150~200 nm的中空纳米球组成,且具有较大比表面积(82.6 m2/g)。采用丝网印刷技术将SnO2气敏浆料涂覆到叉指电极上,制成厚膜型气体传感器器件,研究其对氢气的气敏性能。结果表明SnO2中空纳米球在较低温度(200℃)下对5~200μl/L氢气具有较高的响应值及较快的响应速度,这归因于所制备的SnO2材料的中空结构和较大比表面积,利于氢气气体的吸附与扩散。     

Experimental study on gas–liquid dispersion and mass transfer in shear-thinning system with coaxial mixer

The effects of impeller type, stirring power, gas flow rate, and liquid concentration on the gas–liquid mixing in a shear-thinning system with a coaxial mixer were investigated by experiment, and the overall gas holdup, relative power demand, and volumetric mass transfer coefficient under different conditions were compared. The results show that, the increasing stirring power or gas flow rate is beneficial in promoting the overall gas holdup and volumetric mass transfer coefficient, while the increasing system viscosity weakens the mass transfer in a shearing–thinning system. Among the three turbines, the six curved-blade disc turbine (BDT-6) exhibits the best gas pumping capacity; the six 45° pitched-blade disc turbine (PBDT-6) has the highest volumetric mass transfer coefficient at the same unit volume power.     

Impact of gypsum on flotation of scheelite and fluorite using sodium oleate as collector

ABSTRACT

In this study, effect of calcium and gypsum on scheelite and fluorite was investigated using sodium oleate as collector. Micro-flotation and contact angle results showed that the adsorption of calcium could inhibit the hydrophobicity of scheelite and fluorite. Moreover, sulfate could enhance the inhibition. FT-IR results showed that calcium could be priori precipitated into calcium oleate and adsorb on mineral surface. The adsorption of calcium could increase the scheelite potential to IEP, while it showed limited effect on fluorite potential. However, the interaction of calcium on scheelite and fluorite in gypsum solution was more complex than that in calcium solution.     

Microstructure and damage evolution of SiCf/PyC/SiC and SiCf/BN/SiC mini-composites: A synchrotron X-ray computed microtomography study

SiC_f/PyC/SiC and SiC_f/BN/SiC mini-composites comprising single tow SiC fibre-reinforced SiC with chemical vapor deposited PyC or BN interface layers are fabricated. The microstructure evolutions of the mini-composite samples as the oxidation temperature increases (oxidation at 1000, 1200, 1400, and 1600?°C in air for 2?h) are observed by scanning electron microscopy, energy dispersive spectrometry, and X-ray diffraction characterization methods. The damage evolution for each component of the as-fabricated SiC_f/SiC composites (SiC fibre, PyC/BN interface, SiC matrix, and mesophase) is mapped as a three-dimensional (3D) image and quantified with X-ray computed tomography. The mechanical performance of the composites is investigated via tensile tests.The results reveal that tensile failure occurs after the delamination and fibre pull-out in the SiC_f/PyC/SiC composites due to the volatilization of the PyC interface at high temperatures in the air environment. Meanwhile, the gaps between the fibres and matrix lead to rapid oxidation and crack propagation from the SiC matrix to SiC fibre, resulting in the failure of the SiC_f/PyC/SiC composites as the oxidation temperature increases to 1600?°C. On the other hand, the oxidation products of B₂O₃ molten compounds (reacted from the BN interface) fill up the fracture, cracks, and voids in the SiC matrix, providing excellent strength retention at elevated oxidation temperatures. Moreover, under the protection of B₂O₃, the SiC_f/BN/SiC mini-composites show a nearly intact microstructure of the SiC fibre, a low void growth rate from the matrix to fibre, and inhibition of new void formation and the SiO₂ grain growth from room to high temperatures. This work provides guidance for predicting the service life of SiC_f/PyC/SiC and SiC_f/BN/SiC composite materials, and is fundamental for establishing multiscale damage models on a local scale.     

基于物联网的智能化窨井管理系统的设计

通信管道承载着户外传输网络,是通信网络的生命管道。管道规模伴随着城市化进程快速成倍增长,但管道管理还处于传统的依赖人工专项梳理、专项盯防的模式。随着智慧城市建设的加速推进,采用“物理加锁+物联网管理平台”的创新管理方式,结合物联网技术和大数据技术,实现对流程、人员、设备的全方位管理。     

Cross‐Linked Fluorinated Poly(Aryl Ether) (C‐FPAE) Films: Preparation Strategy,Performance Study,and Low Dielectric Applications

The production of low dielectric materials that can be used in high temperature environments is the primary aim of this work. A cross‐linked structure is introduced into fluorinated poly(aryl ether) (named as FPAE) with high molecular weight (M_w, 140 000 g mol^?1) and linear molecular structure using nucleophilic substitution reaction at the ortho‐position of decafluorobiphenyl monomer units in the FPAE molecular chain. The curing temperature and curing time are optimized and the final conditions for the cross‐linking reaction in this study are determined to be 300 °C for 1 h. Moreover, the dielectric constant and dielectric loss of the C‐FPAE film respectively are 2.67 and 0.006 at 1000 Hz when 1 wt% of crosslinking agent is added, and the cross‐linked fluorinated poly(aryl ether) film shows excellent thermal stability (T_d(5%), 495 °C), dimensional stability, hydrophobic properties, and high storage modulus in high temperature environments. Such novel low dielectric material with excellent performances has important application value in the aerospace and the integrated electronics field.     

Preparation of Pd/PANI/ITO composite electrode and its degradation of tetracycline wastewater

In order to treat antibiotics organic pollutants in the water environment, the Pd/PANI/ITO composite electrode was prepared by the galvanostatic electrodeposition method in this paper. The surface morphology and electrocatalytic activity of the electrode were analyzed and tested. Using the degradation rate of electrocatalytic tetracycline wastewater as an indicator, the optimal parameter conditions for preparing the composite electrode were screened out: the optimal deposition current of PANI was 2 mA, and the deposition time was 10 min. The optimal deposition current for Pd is 2 mA, and the deposition time is 10 min. The optimal current for the degradation of tetracycline wastewater is 10 mA, and the relationship between the degradation current and the degradation time conforms to the pseudo-first-order reaction kinetics. The existence of ·OH in the degradation process of tetracycline was verified by the coumarin fluorescence detection technology. Finally, the degradation process of tetracycline wastewater is analyzed. The results show that the intermediate products produced during the degradation of tetracycline are gradually cleavage of tetracycline molecules, and they are eventually converted into CO₂ and H₂O.     

Application of distributed motion estimation for swarm MAVs in a GPS-restricted environment based on a wireless sensor network

The Journal of Supercomputing - To meet the requirements for motion estimation of a swarm of micro-aerial vehicles in a GPS-restricted environment, a distributed motion estimation algorithm is...