高职电气类专业工作过程系统化课程的开发

工作过程系统化课程开发的核心载体是工作任务,其教学内容与具体工作情境和工作过程紧密相连,可实现"工作"与"教学"一体化的综合发展.本文以高职电气类专业课程的开发过程为例,讨论了原学科体系下"电气控制技术"课程教学的弊端,提出了按工作过程系统化进行开发的"常用电气设备控制与检修"课程的结构,内容,学习情境的具体设计,结合该课程改革分析了学习情境设计的相关原则.     

Effects of nitrogen doping on surface-enhanced Raman scattering (SERS) performance of bicrystalline TiO2 nanofibres

In this work, we successfully synthesized bicrystalline anatase/TiO_2(B) nanofibre and used it as active substrate for surface-enhanced Raman scattering(SERS) applications. The bicrystalline structured TiO_2 substrates provide additional charge transfer across the anatase-TiO_2(B) interface and thus enhanced activity compared to the pure single crystalline phase. With an effort to further increase the sensitivity of SERS, nitrogen element was doped into bicrystalline anatase/TiO_2(B) nanofibres(N-TiO_2) and higher SERS enhancement was achieved. The nitrogen content was controlled by tuning the calcination temperature of titanate precursor at 500, 600 and 700 °C,respectively. The sample calcined at 600 °C(NT600) acquires the highest percentage of nitrogen element due to its open pore structure that facilitates the diffusion of nitrogen during calcination. Raman intensity depends on the amount of nitrogen doping, thus NT600 exhibited the best SERS activity. The doped nitrogen in TiO_2 facilitates the charge transfer between TiO_2 and probing molecules and thus suppresses the electron–hole recombination. This work provides a new perspective on the design of efficient TiO_2 SERS active substrate and is expected to be valuable for adsorbate detection on semiconductor surface.     

Renewable hydrogen production from steam reforming of glycerol (SRG) over ceria-modified γ-alumina supported Ni catalyst

Excess crude glycerol derived as a by-product from biodiesel industry prompts the need to valorise glycerol to value-added chemicals. In this context, catalytic steam reforming of glycerol (SRG) was proposed as a promising and sustainable alternative for producing renewable hydrogen (H₂). Herein, the development of nickel (Ni) supported on ceria-modified mesoporous γ-alumina (γ-Al₂O₃) catalysts and their applications in catalytic SRG (at 550–750 °C, atmospheric pressure and weight hourly space velocity, WHSV, of 44,122 ml·g⁻¹·h⁻¹ (STP)) is presented. Properties of the developed catalysts were characterised using many techniques. The findings show that ceria modification improved Ni dispersion on γ-Al₂O₃ catalyst support with highly active small Ni particles, which led to a remarkable catalytic performance with the total glycerol conversion (ca. 99%), glycerol conversion into gaseous products (ca. 77%) and H₂ yield (ca. 62%). The formation rate for H₂ production (14.4 × 10⁻⁵ mol·s⁻¹·g⁻¹, TOF (H₂) = 3412 s⁻¹) was significantly improved with the Ni@12Ce-Al₂O₃ catalyst, representing nearly a 2-fold increase compared with that of the conventional Ni@Al₂O₃ catalyst. In addition, the developed catalyst also exhibited comparatively high stability (for 12 h) and coke resistance ability.     

Preparation of WO_3 thin films by dip film-drawing for photoelectrochemical performance

Here we report the WO_3 thin films on F-doped SnO_2 conducting glass(FTO) substrates which were prepared by using dip film-drawing method. Dip film-drawing was a simple, convenient, economical method and in largescale to prepare photoanodes for future applications. The FTO substrates were dipped in tungstic acid solution then film-drawn included 3, 6, 9, 12 and 15 times for prepared different thicknesses of WO_3 thin film photoanodes. Then the photoanodes were employed as the electrodes in photoelectrochemical property measurements, which include scan linear sweep, repeated on/off illumination cycles, electrochemical impedance spectroscopy and incident photon to current conversion efficiency, respectively. The results showed that the WO_3 thin films dipped 9 times with 175 nm thicknesses had the best photoelectrochemical performance of 0.067 mA·cm~/(-2) at 1.23 V versus RHE.     

Feasibility analysis of SO2 absorption using a hydrophilic ceramic membrane contactor

Hydrophilic ceramic membranes would be potential candidates for membrane gas absorption if they could be applied to appropriate separation processes. This study highlights a novel concept for the practical implementation of SO₂ absorption in hydrophilic ceramic membrane that exhibits outstanding thermal and mechanical stabilities. With this aim, we investigated experimentally the performance of SO₂ absorption into aqueous sodium hydroxide (NaOH) solution in a hydrophilic alumina (Al₂O₃) membrane contactor in terms of SO₂ removal efficiency and SO₂ mass transfer flux, and compared the performance with that in a hydrophobic one. A series of experiments were performed at various conditions over a NaOH concentration range of 0-1.0 mol·L^-1, a liquid flow rate range of 30-180 ml·min^-1, a gas flow rate range of 120-1000 ml·min^-1, an inlet SO₂ concentration range of 400-2000 μl·L^-1, and a temperature range of 10-35℃. It was found that the hydrophilic membrane was more competitive when using a NaOH concentration higher than 0.2 mol·L^-1. Furthermore, it can be inferred that the hydrophilic α-Al₂O₃ membrane exhibited exceptional long-term stability under 480 h continuous operation.     

A Graph-based Ant Colony Optimization Approach for Integrated Process Planning and Scheduling

This paper considers an ant colony optimization algorithm based on AND/OR graph for integrated process planning and scheduling (IPPS). Generally, the process planning and scheduling are studied separately. Due to the complexity of manufacturing system, IPPS combining both process planning and scheduling can depict the real situation of a manufacturing system. The IPPS is represented on AND/OR graph consisting of nodes, and undirected and directed arcs. The nodes denote operations of jobs, and undirected/directed arcs denote possible visiting path among the nodes. Ant colony goes through the necessary nodes on the graph fromthe starting node to the end node to obtain the optimal solution with the objective of minimizing makespan. In order to avoid local convergence and lowconvergence, some improved strategy is incorporated in the standard ant colony optimization algorithm. Extensive computational experiments are carried out to study the influence of various parameters on the system performance.     

Solid-liquid Extraction Spectrophotometric Determination of Copper with 2,9-dimethyl-1,10-phenanthroline

Solid-liquid extraction deterndnation andseparation of metal ions has been well devel-oped in recent year[l--4]. The deterndnation oflanthanides and precious metals were exten-siveIy investigated by using solid diluent sol-vent in our previous works[5--7]. These previ-ous studies indicate that high temPerature andlow melting point solvent give a lot of advan-tages which is absent in room temPeratllrecommon liquid-liquid extraction.Copper(I) and neo-cuproine can stronglyform a yellow colored …     

气体在水中无限稀释扩散系数的关联

对于稀溶液，假定扩散阻力主要来源于粘度，结合粘度定义，推导出无限稀释扩散系数基本方程。若分子形状按球形处理，则分子间距离和分子表面积可通过摩尔体积计算，进一步可得到无限稀释扩散系数方程。考虑到水的缔合作用，在方程中引入水的缔合参数，对各种气体在水中无限稀释扩散系数共有７７个数据点的关联，得到缔合参数ｎｗ为１．６７。计算结果总平均偏差为８．６％，准确性高于文献方程。