Processing of high-performance Co doped Y2O3 as a single-phase electrolyte for low temperature solid oxide fuel cell (LT-SOFC)

The high-performance single-phase semiconductor materials with higher ionic conductivity have drawn substantial attention in fuel cell applications. Semiconductor materials play a key role to enhance ionic conductivity subsequently promoting low temperature solid oxide fuel cell (LT-SOFC) research. Herein, we proposed a semiconductor Co doped Y₂O₃ (YCO) samples with different molar ratios, which may easily access the high ionic conductivity and electrochemical performances at low operating temperatures. The resulting fabricated fuel cell 10% Co doped Y₂O₃ (YCO-10) device exhibits high ionic conductivity of ∼0.16 S cm⁻¹ and a feasible peak power density of 856 mW cm⁻² along with 1.09 OCV at 530 °C under H₂/air conditions. The electrochemical impedance spectroscopy (EIS) reveals that YCO-10 electrolyte based SOFC device delivers the least ohmic resistance of 0.11–0.16 Ω cm² at 530-450 °C. Electrode polarization resistance of the constructed fuel cell device noticed from 0.59 Ω cm² to 0.28 Ω cm² in H₂/air environment at different elevated temperatures (450 °C to 530 °C). This work suggests that YCO-10 can be a promising alternative electrolyte, owing to its high fuel cell performance and enhanced ionic conductivity for LT-SOFC.     

Response of osteoblast-like MG63 cells to TiO2 layer prepared by micro-arc oxidation and electric polarization

Micro-arc oxidation (MAO) is one of the useful surface modifications of titanium implants to improve bioactivity. Also, electric polarization treatment enhances bioactivity of calcium phosphate. The aim of this study was to evaluate the effect of the combination of two surface modifications, micro-arc oxidation (MAO) with electric polarization, on the behavior of osteoblast-like osteosarcoma MG63 cells. MAO-treated materials had a surface geometry that was favored by MG63 cells as determined using scanning electron microscopy and X-ray diffraction; additionally, electric polarization induced surface electric fields, which were measured using thermally stimulated depolarization currents. The results of assays to study cell–material interactions suggest that these two approaches could regulate cell attachment, spreading, proliferation, and differentiation without the addition of other reagents. This new surface modification processes produce materials with a good surface geometry, generate surface electric fields and enhance the osteopromotive ability of osteoblasts.     

Prediction of evaporation losses in evaporative fluid coolers

The accurate prediction of various aspects of thermal behavior of evaporative fluid coolers is very important for both design and rating calculations. Exactly predicting evaporation losses is significant since the process fluid is cooled primarily by evaporation of a portion of the recirculating water that causes the concentration of dissolved solids and other impurities to increase. An empirical relation to predict evaporation losses is developed on the basis of the rule of thumb recommended by manufacturers, which is simple and accurate with a wide range of applicability. The predicted values are in good agreement with the numerical values obtained from the calibrated model where the maximum error was found to be approximately 4% but often less than 2%.     

Mechanism of ceramic slurry light scattering affecting contour accuracy and method of projection plane correction

Digital light processing (DLP) is a relatively mature ceramic additive manufacturing technology widely applied in medical bone implantation, electronic communication, and other fields. However, the size error caused by the light scattering from the complex contour can seriously affect the precision and forming quality of the printed green body. This paper studied the scattering behavior of complex structure ceramics under different exposure energies through two structural parameters: exposure width and contour shape. A formula for excess cure width is presented. The formula will be then applied to simplify the machine learning algorithms. Finally, by inverse compensation for the complex contour, we optimized some pore structures and complex shapes to greatly improve the fidelity of the structure.     

The effect of tricalcium silicate incorporation on bioactivity,injectability, and mechanical properties of calcium sulfate/bioactive glass bone cement

The conventional Polymethyl methacrylate (PMMA) bone cement is not biodegradable and not bioactive to bond with the native bone and causes tissue necrosis resulting from its high exothermic polymerization. Hence, biodegradable bioactive bone cements with suitable setting time and mechanical properties should be introduced. In this study, novel bioactive bone cements containing Calcium Sulfate Hemihydrate (CSH), Bioactive Glass (BG), and Tricalcium Silicate (TSC) were developed. Firstly, CSH and BG binary system was optimized based on preliminary setting and mechanical tests. Secondly, the composite bioactive bone cements were obtained by adding different quantities of TCS to the optimized CS-BG (1.3:1 wt % ratio) system. All groups exhibited desirable handling properties, an initial setting time of lower than 15 min, injectability of greater than 85%, and controlled degradability. Moreover, they demonstrated initial compressive strength values of higher than 12 MPa, superior to trabecular bone. After 28 days of hydration, the compressive strength of the cement containing 30% TCS reached 51.04 MPa. Furthermore, the present bone cements showed favorable bioactivity and bone-bonding ability as a result of calcium carbonate and hydroxyapatite (HA) formation. Furthermore, this novel bone cement exhibited appropriate biocompatibility and mesenchymal stem cell attachment, suggesting its potential for clinical applications.     

基于单片机的氧指数仪控制器开发

为适应最新国家标准,并且提高氧指数测定的准确性和效率,基于单片机开发了智能氧指数仪控制器。介绍了氧指数的测定原理,重点阐述了控制器的总体方案设计和硬件设计,随后介绍该控制器采用的一种参数自整定的模糊PID控制算法及其软件实现。实验结果表明该控制器性能优异,符合国家标准要求,具有较强的实用性。     

多感应器感应加热电源的参数辨识及功率解耦控制

为实现不规则金属工件的梯度加热和功率控制,设计了一种三段式感应器的感应加热电源,可以控制3个感应线圈的分段和联合加热．以铝合金为例,对频率、功率和加热时间等关键参数建立了数学模型并给出了辨识方法;通过建立和分析三段式感应加热电源的等效电路,针对彼此间存在的耦合问题进行了研究,得出了三段以及多段感应器的输出电流同相是功率解耦的关键．根据此理论建立了仿真模型和研制了一台样机,仿真结果表明通过递推最小二乘参数估计算法能够获得理想的辨识模型,加热的频率和功率分别在递推300次和1 000次后达到了允许的误差;样机实验结果说明该方法有效地消除了各段感应线圈的功率耦合,能够精确地实现不规则金属的梯度加热和功率控制．     

Influence of dynamic strain aging pre-treatment on the low-cycle fatigue behavior of modified 9Cr–1Mo steel

The influence of dynamic strain aging (DSA) pre-treatment on the low-cycle-fatigue (LCF) behavior of modified 9Cr–1Mo steel was investigated at 550 °C. The DSA pre-treatment reduces the fatigue life, which is reflected on the fracture surface as multiple crack initiation. The samples pre-treated by DSA have higher peak tensile stress and positive mean stress effects, which is responsible for the lifetime reduction. The DSA pre-treatment does not change cross-slip mechanisms during mechanical cycling, compared without DSA process, but results in accelerating the microstructure transformation from lath to cells with low dislocation densities, which reduces the number of cycles to failure.     

Effect of refrigerant flow direction and throttle opening in RAC unit using micro-channel evaporator

Experimental comparisons are made on the performance of a room air conditioner using micro-channel evaporator with the refrigerant flowing in the Upward Flow mode (UF mode, meaning refrigerant flowing upward from the bottom) and Downward Flow mode (DF mode, meaning refrigerant flowing downward from the top). Test results show that UF mode develops a superior refrigerant distribution in the micro-channels to what DF mode does. This is then illustrated by the infrared thermographs at the nominal operating condition. Subsequently, the effect of the width of throttle opening on the sample unit performance is investigated experimentally in the micro-channel evaporator adopting the UF mode. Measurement and calculation results of pressure difference between evaporator inlet and outlet, mean temperature of the evaporator surface, cooling capacity, input power and EER show that the tested unit operates with the best performance with the refrigerant pressure of 993.61 kPa at the inlet of micro-channel evaporator. Infrared thermographs of the working evaporator verify this conclusion.     

Influence of the compaction process on the air void homogeneity of asphalt mixtures samples

The effectiveness of laboratory compaction methods, for reproducing asphalt mixtures specimens with the same characteristics as on the actual building site, remains relatively unknown. The present paper is aimed at investigating the variability in air void content, therefore in compaction level, of three asphalt mixture types: a continuously-graded mix, an open-graded sandy mix, and a gap-graded asphalt. Several types of compactors are tested and the influence of sample dimensions and compaction axis vs. the main sample axis regarding air void homogeneity are studied using gamma-ray measurement. This study shows that for the studied materials, the samples cored in the plate are the most homogeneous, the ones produced by gyratory compaction yield scattered results but rather homogeneous samples can be obtained by respecting geometry criteria for the samples to be produced, and by sawing the edges where the compaction is the least efficient.