Fabrication and characterization of nano silver powder prepared by spray pyrolysis

Silver powder was fabricated by spray pyrolysis, using 2%–20% AgNO₃ solution, 336–500 mL/h flux of AgNO₃ solution, 0.28–0.32 MPa flux of carrier gas and in the 620–820 °C temperature range. The effects of furnace set temperature, concentration of AgNO₃ aqueous solution, flux of AgNO₃ aqueous solution as well as carrier gas on the morphology and particle size distribution of silver powder, were investigated. The experimental results showed that with the high concentration of AgNO₃ aqueous solution, the average grain size of silver decreased with the increasing of furnace set temperature. But the gain size distribution was not homogenous, the discontinuous grain growth occurred. With the low concentration of AgNO₃ aqueous solution, the higher furnace set temperature made the nano sliver grains sintered together to grow. Nano silver powder about 100 nm was fabricated by spray pyrolysis, using 2wt% AgNO₃ solutions, 336 mL/h flux of AgNO₃ aqueous solution, 0.32 MPa flux of carrier gas at 720 °C furnace set temperature.     

Relationship of hydrocarbon and source-rock in Nos.3-5 tectonic belts of the Lenghu area, northern Qaidam Basin

Based on analyses of the components of crude oil hydrocarbons and carbon isotopes, the content of normal alkane de-creased from 49.00% to 20.10% when moving from the No.3 to No.5 tectonic belt of the Lenghu area of the Qaidam Basin, while cycloalkanes increased from 30.00% to 52.20% and aromatic and branch chain alkanes increased gradually as well. The maturity of sterane in crude oil is higher than that of its source-rock, which shows that the hydrocarbons were generated from a deep source-rock of high maturity around the tectonic belts of the Lenghu area. The analysis of the characteristics of carbon isotopes also shows that these isotopes of hydrocarbon compounds in the No.4 and No.5 tectonic belt are apparently heavier than those in the No.3 belt. The results of our research show that the hydrocarbons in the No.3 tectonic belt are mainly from a relatively rich sapropelic substance, while the hydrocarbons in the No.4 and No.5 tectonic belt originated mainly from organic matter of a rela-tively rich humic type substance.     

数控加工三维场景几何建模技术研究

讨论了基于构件技术的数控加工三维场景建模技术,并以OpenGL和Visual C++6.0为开发平台,开发出一个基于STL文件格式的建模系统.     

块体非晶合金制备方法的研究进展

对大块非品合金的制备方法进行了总结和归纳,阐述了不同制备方法的基本原理,并对各种制备方法的优缺点进行了讨论.最后根据对不同制备方法的分析及探讨,对大块非晶合金制备方法的研究方向进行了展望.     

A nonlinear control method for the electromagnetic suspension system of the maglev train

To deal with the inherent nonlinearity and open-loop instability of the electromagnetic suspension (EMS) system, a new nonlinear control method is proposed. The simulation results show that, for a PID controller, the overshoot of the system response to an airgap step disturbance is about 3 mm, and the transient time is 6 s; however, for the proposed nonlinear controller, there is no overshoot and transient time within 2 s. The proposed method has a faster response and stronger robustness. With a designed bi-DSP suspension controller, this nonlinear control method was implemented on the Shanghai Urban Maglev Test Line (SUMTL) to validate its effectiveness and feasibility.

     

仿土质专用肥的开发和应用前景

本文介绍了基于某些名、优农产品在其生长过程中所需要的特定敏感元素,配制出“仿土质”专用肥。经施用证明,肥效显著,经济效益可观,具有推广应用的前景。     

异辛酸钴的制备和应用

采用硫酸钴沉淀法制备异辛酸钴,并在水相与有机相的分离过程中添加助剂的方法,可使分离后有机相不经水洗即可彻底除去SO_4~(2-)离子,简化了工艺流程。介绍了异辛酸钴催干剂在4种醇酸磁漆中的应用及其性能检测结果。检测结果表明,异辛酸钴用于醇酸磁漆的性能指标达到或超过规定标准,尤其光泽、硬度两项指标优于同类产品水平,町作为环烷酸钴等常用催干剂的更新换代产品。     

卫生瓷坯体配方的改进

利用本地瓷石和厂内废料代替河北邢台碱、长石和部分石英生产卫生瓷，可降低产品烧成温度，提高产品质量。     

Thermal analysis of montmorillonites modified with quaternary phosphonium and ammonium surfactants

The thermal stability of seven organically modified montmorillonites (‘organoclays’) has been investigated using differential thermal analysis, differential scanning calorimetry, and thermogravimetry in conjunction with X-ray diffractometry. Six organoclays were synthesised by replacing the interlayer inorganic cations, initially present, with quaternary phosphonium and ammonium surfactant cations. The samples modified with tetrabutylphosphonium (TBP), and butyltriphenylphosphonium (BTPP) ions have an appreciably higher thermal stability than the octadecyltrimethylammonium (ODTMA)-modified clays. Thus, in the case of TBP- and BTPP-modified montmorillonites, the onset temperature of decomposition is close to 300 °C. Samples modified with hexadecyltributylphosphonium (HDTBP) ions have a lower onset temperature of decomposition of 225 °C. In comparison, the onset temperature for ODTMA-montmorillonites (obtained at different concentrations of ODTMA-bromide) ranges from 158 to 222 °C, being highest where the concentration of intercalated surfactant is lowest. The onset temperature for a commercial alkylsilane-treated quaternary ammonium-modified organoclay (S-BEN N-400FP) is 207 °C. The basal spacing of the TBP- and BTPP-modified clays is 1.7–1.8 nm, indicating a monolayer arrangement of quaternary phosphonium ions in the interlayer space, while the value of 2.5 nm for HDTBP-montmorillonite indicates a more open structure. The ODTMA-modified samples have basal spacings ranging from 1.9 to 2.1 nm, indicative of a bilayer to pseudo-trilayer arrangement. The exceptionally high basal spacing of 3.4 nm for the S-BEN N-400FP organoclay might be due to interlayer penetration of organosilane hydrolysis products during synthesis. The thermal properties of organoclays are apparently related to the nature of the surfactants and their arrangement in the interlayer space of montmorillonite.     

Finite Time Synchronization of Delayed Quaternion Valued Neural Networks with Fractional Order

Neural Processing Letters - In this article, the finite time (FT) synchronization problem of fractional order quaternion valued neural networks with time delay is investigated. Without separating...