Effect of high temperature on the mechanical properties of hierarchical porous cenosphere/geopolymer composite foams

A hierarchical porous cenosphere/geopolymer composite foam (FHCs/KGP) was fabricated by the simultaneous incorporation of O₂ pore from hydrogen peroxide and cenosphere filler addition. Effects of both H₂O₂ content and high-temperature treatment on the microstructure, porosity and strength of porous FHCs/KGP foams were investigated systematically. The obtained FHCs/KGP foams showed typical amorphous structure and desirable porosity from 65 to 82%. The composites could crystallize in situ to FHCs/leucite foams above 1000℃. Compression strength of the FHCs/leucite foams showed a maximum value of 5 ± 0.3 MPa when treated at 1000°C. The improvement of mechanical properties for the composite foams was attributed to crack deflection, fractured microspheres and the good bond between the FHCs and matrix. This study could open opportunities to employ cellular foams as alternatives in structure and filtration applications.     

Effect of SiC nanowhisker addition on microstructure and mechanical properties of regenerated cemented carbides by low-pressure sintering

The hardness and toughness of regenerated cemented carbides, in general, are contradictory. Therefore, it is critical to explore regenerated cemented carbides with both high hardness and high toughness. In this study, regenerated WC-8-wt% Co cemented carbide with SiC nanowhisker were prepared by low-pressure sintering. The influence of SiCw contents on the microstructure and mechanical properties of regenerated WC-8-wt% Co cemented carbide was investigated. The results indicated that the hardness, density, flexural strength, and fracture toughness of regenerated cemented carbide first increased and then decreased with the addition of SiCw. The Vickers hardness, density, flexural strength, and fracture toughness could reach 1575 HV, 14.6 g/cm³, 2204 MPa, 16.85 MPa·m^1/2, respectively, with SiCw content 0.5 wt%, which were increased by 14.4%, 0.7%, 12.2%, and 17.3%, respectively, when compared with the regenerated cemented carbide without SiCw. The lowest friction coefficient and the best wear resistance could be also reached when 0.5-wt% SiCw was added. The fracture mechanism of the regenerated cemented carbide contained both transgranular and intergranular fracture through the microscopic observation of fracture surface via scanning electron microscope.     

基于包络线聚类的多模融合超短期光伏功率预测算法

针对传统功率预测方法以气象因素进行聚类划分时各气象因素权重难以分配以及单模型预测精度较差的问题,提出一种基于光伏功率包络线聚类的多模融合超短期光伏功率预测算法.对异常特征数据进行预处理,采用Pearson相关系数与XGB Feature Importance模块分析光伏功率和各特征之间的相关关系,并构建新特征;介绍包络线理论,并根据光伏功率包络线参数进行聚类划分,将聚类后的数据作为输入,借鉴Stacking集成学习框架构造XGBoost+LightGBM+LSTM融合模型对光伏功率进行预测;将所提算法与气象因素聚类和功率区间聚类下的各预测算法进行实验对比;为了避免训练过程中模型超参数的影响,采用K折交叉验证对数据的训练集、验证集和测试集进行划分.仿真结果表明,所提算法较气象因素和功率区间聚类法能有效提高复杂天气情况下光伏功率预测精度,且多模融合效果总体优于单独算法模型.     

First-Principles Investigation of the Interfacial Stability,Precipitate Formation,and Mechanical Behavior of Al3Li/Al3Zr/Al Interfaces

Metallurgical and Materials Transactions A - Precipitates including Al3Li, Al3Zr and core–shell structured Al3Li (Al3Zr) produce significant strengthening effects in Al-Li alloys by means of...     

碳纳米管及C60和石墨氧化动力学机理函数的分析

The oxidation of carbon nanotubes, C60 and graphite was studied by thermogravimetric (TG) analysis and differential thermal analysis (DTA) technique, and the oxidation kinetic models of three carbon materials studied were analyzed by mechanism-function method. The results indicate that three carbon species adopt different oxidation mechanisms due to their different structures. The oxidation of carbon nanotubes with cylindrical structure follows contracting volume reaction mechanism [R3 mechanism, 1-(1-α)1/3 = kt], indicating that the oxidation of carbon nanotubes takes place from the ends to the center. For graphite with planar sandwich structure, the oxidation starts at the edges initially and gradually moves toward the center, which corresponds to contracting area phase boundary reaction mechanism [R2 mechanism, 1-(1-α)1/2 = kt]. The oxidation of C60 with spherical structure, however, is complex and apparently cannot be illustrated with a single kinetic model. The values of apparent activation energy     

水性聚氨酯木器漆中消泡剂的选用

水性聚氨酯木器漆极易产生气泡,影响其装饰性。通过系列试验,筛选出适宜的消泡剂,并确定其最佳用量。     

The mechanism of color reversion in soybean salad oil

An enzymatic reaction might be the major cause of color reversion in soybean oil. During the soybean flaking process, enzymatic reactions take place to convertγ-tocopherol to 5-(tocopheryloxy)-γ-tocopherol (γ-TED), and then further convertγ-TED to the precursors which are the cause of color reversion. The variations ofγ-tocopherol andγ-TED contents in soybean oil are accompanied by an inverse change in the precursors’ concentration. Therefore, the contents ofγ-tocopherol orγ-TED in crude soybean oil could be used as an index for predicting the color quality (color reversion) of soybean salad oil. Almost all the precursors (such as tocored) were converted to color-reverted substances under catalysis after bleaching treatment, and they were converted back to the precursors during deodorization. Those precursors might be gradually reconverted into the color reverted substances during storage to cause the color reversion in soybean salad oil.     

表达重组人可溶性TRAIL的毕氏酵母发酵工艺

目的优化rhsTRAIL毕氏酵母工程菌在5L发酵罐中的发酵表达工艺参数。方法研究培养基种类、细胞密度、甘油含量、pH值、甲醇浓度、甲醇流加速率及诱导时间等参数对工程菌生长及目的蛋白表达的影响,并用电镜观察其诱导肿瘤细胞凋亡特征。结果在无机盐培养基中,按10%接种A600=8～12的种菌后,24h酵母菌增殖至A600=76;甘油含量为1%时,菌体生长速度快(A600=160);培养基pH值5.0,甲醇终浓度为1%时,诱导96h表达量最高达到120mg/L,并具有诱导肿瘤细胞凋亡特征。结论rhsTRAIL毕氏酵母的发酵工艺参数为无机盐培养基,pH值5.0,接种10%A600=8～12的种菌,甘油含量1%,甲醇终浓度1%,诱导96h。     

相位测量定位法在焦炉车辆上的应用与研究

文中通过测量载波相位进行定位的方法来解决焦炉车辆的定位问题，以达到无线定位的目的。并对定位的数学模型进行了详细的分析与论述。