Improved Compaction in Multilayer Capacitor Fabrication

The most common defects found in multi-layer ceramic capacitors are derived from residual porosity formed when solvents and binders are released from a ceramic green body. Without a well-controlled compaction technique, defects between sheets in the stacked body are often present, leading to lamination problems. This paper suggests alternative approaches, using compaction applied before and/or after the process of binder burnout with the intention of reducing the number of stacking-generated defects and the volume of voids formed after binder burn-out. Barium titanate tapes and stacked multilayer electroded discs have been investigated and characterised by microstructural examination and density measurement. The resulting properties are described, and the behaviour of the multi-layers discussed in terms of the microstructure and processing procedures. It is shown that the porosity content of sintered samples compacted at 300 MPa is approximately half that of samples compacted at 30 MPa when both are sintered at 1300°C for 2 h. A further improvement of densification can be achieved by a postcompaction treatment after binder burn out.     

卧式加工中心整机防护控制功能开发与应用

为加工中心配置整机防护,通过PLC程序对安全门进行动作控制,同时通过检测开关辨认安全门的状态,判断加工区域存在人员的可能性,在程序中进行安全互锁的处理,尽量避免安全事故的发生。在满足生产和维修需要的前提之下,更好地保障操作者的安全,提高加工中心的实用性。     

Performance enhancement of energy extraction capability for fuel cell implementations with improved Cuckoo search algorithm

This paper addresses an improved optimization method to enhance the energy extraction capability of fuel cell implementations. In this study, the proposed method called Dynamic Cuckoo Search Algorithm (DCSA) is tested in a stand-alone fuel cell in order to control the system power under dynamic temperature response. In the operational process, a fuel cell is connected to a load through a dc-dc boost converter, and DCSA is utilized to adjust the switching duration in dc-dc converter by using voltage, current and temperature parameters. In this way, it controls the output voltage to maximize power delivery capability at the demand-side and eliminates the drawback of conventional cuckoo search algorithm (CSA) which cannot change duty cycle under operating temperature variations. In this regard, DCSA shows a significant improvement in terms of system response and achieves a more efficient power extraction than the conventional CSA method. In order to demonstrate the system performance, the stand-alone fuel cell system is constructed in Simulink environment via a processor-in the-loop (PIL) based digital implementation and analyzed by using different optimization methods. In the analysis section, the results of the proposed method are compared with conventional methods (perturb&observe mppt, incremental conductance mppt, and particle swarm optimization). In this context, convergence speed and efficiency analysis for both methods verify that the DCSA gives original results compared to conventional methods.     

Potentiality of combined catalyst for high quality bio-oil production from catalytic pyrolysis of pinewood using an analytical Py-GC/MS and fixed bed reactor

The aim of this study was to investigate the potential of combined catalyst (ZSM-5 and CaO) for high quality bio-oil production from the catalytic pyrolysis of pinewood sawdust that was performed in Py-GC/MS and fixed bed reactor at 500 °C. In Py-GC/MS, the maximum yield of aromatic hydrocarbon was 36 wt% at biomass to combined catalyst ratio of 1:4 where the mass ratio of ZSM-5 to CaO in the combined catalyst was 4:1. An increasing trend of phenolic compounds was observed with an increasing amount of CaO, whereas the highest yield of phenolic compounds (31 wt%) was recorded at biomass to combined catalyst ratio of 1:4 (ZSM-5: CaO - 4:1). Large molecule compounds could be found to crack into small molecules over CaO and then undergo further reactions over zeolites. The water content, higher heating value, and acidity of bio-oil from the fixed bed reactor were 21%, 24.27 MJkg⁻¹, and 4.1, respectively, which indicates that the quality of obtained bio-oil meets the liquid biofuel standard ASTM D7544-12 for grade G biofuel. This research will provide a significant reference to produce a high-quality bio-oil from the catalytic pyrolysis of woody biomass over the combined catalyst at different mass ratios of biomass to catalyst.     

Response surface analysis of extract yield and flavour intensity of Brazilian cherry (Eugenia uniflora L.) obtained by supercritical carbon dioxide extraction

This work evaluated the effect of pressure and temperature on yield and characteristic flavour intensity of Brazilian cherry (Eugenia uniflora L.) extracts obtained by supercritical CO₂ using response surface analysis, which is a simple and efficient method for first inquiries. A complete central composite 2² factorial experimental design was applied using temperature (ranging from 40 to 60 °C) and pressure (from 150 to 250 bar) as independent variables. A second order model proved to be predictive (p ≤ 0.05) for the extract yield as affected by pressure and temperature, with better results being achieved at the central point (200 bar and 50 °C). For the flavour intensity, a first order model proved to be predictive (p ≤ 0.05) showing the influence of temperature. Greater characteristic flavour intensity in extracts was obtained for relatively high temperature (> 50 °C). Therefore, as far as Brazilian cherry is concerned, optimum conditions for achieving higher extract yield do not necessarily coincide to those for obtaining richer flavour intensity.Industrial relevanceSupercritical fluid extraction (SFE) is an emerging clean technology through which one may obtain extracts free from organic solvents. Extract yields from natural products for applications in food, pharmaceutical and cosmetic industries have been widely disseminated in the literature. Accordingly, two lines of research have industrial relevance, namely, (i) operational optimization studies for high SFE yields and (ii) investigation on important properties extracts are expected to present (so as to define their prospective industrial application). Specifically, this work studied the optimization of SFE process to obtain extracts from a tropical fruit showing high intensity of its characteristic flavour, aiming at promoting its application in natural aroma enrichment of processed foods.     

Catalytic activity of char produced from brown coal for steam-gasification of bitumen oil

There are several kinds of catalyst for tar reduction such as Ni-based catalysts, alkali catalysts, metal catalysts, and char. Char is a nonmetallic material which be generated by the devolatilization of organic materials. In this article, by using an experimental setup we tried to study the effect of char particles as a catalyst on the tar concentration and produced gas from steam gasification of bitumen oil and to introduce effective parameters in the process of syngas generation. With the increase of gasification temperature from 800 to 950°C, the hydrogen increased sharply from 28.4 vol% to 34.9 vol% and 18.5 vol% to 21.3 vol%, while CO decreased from 12.5 vol% to 14.9 vol% and 14.8 vol% to 18.1 vol% for gasification with and without char, respectively. As a result, it was found that the gas produced is not sensitive to the pressure changes.     

烧结温度对RuO2-IrO2-TiO2/Ti氧化物涂层阳极性能的影响

采用Pechini法制备了不同烧结温度的RuO2-IrO2-TiO2/Ti阳极,通过SEM、AFM、EDX、XRD、极化曲线、循环伏安曲线及强化电解寿命试验等测试手段,研究了烧结温度对RuO2-IrO2-TiO2/Ti阳极微观结构和电催化性能的影响。结果表明:烧结温度对RuO2-IrO2-TiO2/Ti阳极的表面形貌有很大的影响;随着烧结温度的升高,阳极析氯活性呈先增加后减小的趋势,而电催化活性呈现相反的趋势;550℃下所得的RuO2-IrO2-TiO2/Ti阳极表现出最高的强化电解寿命。     

Preparation and properties of ce-doped TiO2 photocatalyst

TiO₂ nanoparticles doped with different content of Ce ion were prepared by sol–gel method. The samples were characterized by XRD, XPS, TEM, UV–Vis, and PL, the photocatalytic activity was evaluated by photocatalytic degradation of methylene blue (MB) under the irradiation of fluorescent lamp. The results indicate that Ce ion is incorporated into the lattice of TiO₂, which can restrain the increase of grain size, broaden the absorption region to visible light, and inhibit the recombination of the photo-generated electron and hole pairs. Moreover, the photocatalytic activity of Ce-TiO₂ in MB degradation is evidently enhanced. The MB degradation rate of the sample with Ce:Ti = 0.33% (molar ratio) in 8 h is 90.03%, which is much higher than that of P25 (68.19%).     

XZQ1635重介质浅槽分选机在五龙煤矿选煤厂的应用实践

介绍了XZQ1635重介质浅槽分选机的结构、工作原理及技术特点,并针对该机在五龙煤矿选煤厂生产实践中出现的问题,提出了相应解决办法。