Nb5+掺杂对(Ca0.97Ba0.03)Cu3Ti4O12陶瓷结构与电性能的影响

该文利用固相反应法制备了(Ca0.97Ba0.03)Cu3Ti4-xNbxO12 (x=0,0.01,0.03,0.05,0.07,0.10,0.15,0.20， 摩尔分数)陶瓷。借助X线衍射仪及扫描电子显微镜研究了Nb5+的摩尔分数对(Ca0.97Ba0.03)Cu3Ti4O12陶瓷的相结构及表面微观形貌的影响，借助高低温介电测试系统和阻抗测试仪获得了(Ca0.97Ba0.03)Cu3Ti4-xNbxO12陶瓷电性能变化规律。结果表明，各组分(Ca0.97Ba0.03)Cu3Ti4-xNbxO12陶瓷均为单相立方钙钛矿结构；Nb5+摩尔分数的增加可抑制(Ca0.97Ba0.03)Cu3Ti4-xNbxO12陶瓷晶粒的生长并消除其晶粒异常长大；适量掺杂 Nb+能够有效提高(Ca0.97Ba0.03)Cu3Ti4-xNbxO12陶瓷的晶界电阻，从而降低其介电损耗，且可提高(Ca0.97Ba0.03)Cu3Ti4-xNbxO12陶瓷相对介电常数的温度稳定性。     

银基电接触材料的最新研究进展和展望

贵金属基电接触材料广泛应用于电子、电工行业，而Ag基电接触材料的用途和用量最大。总结了主要银基电接触材料中传统的Ag/Ni、Ag/CdO、Ag/SnO2、Ag/ZnO、Ag/C、Ag/W、Ag/WC材料，以及新型的Ag/CNT、Ag/Graphene、Ag/MAX材料的制备方法、性能、用途和研究现况。综述了近年来在电接触材料的实时原位测试技术，并对熔桥、电弧等现象的观测结果和技术进展，以及模拟仿真技术在电接触材料研究中对熔桥、电弧等研究成果和技术进展。分析了银基电接触材料研究中存在的问题，并展望了发展趋势。     

中国商用车领域的铂族金属需求依然强劲

2020年以来中国商用车市场发生了很多变化，近期卡车销量从疫情萧条中大幅反弹，物流、基建以及排放标准升级共同推动了2020年商用车市场需求，对铂族金属的需求更加有利，对铂金需求的预期增长似乎比对钯金需求更有保障。     

Quantitative analysis of fuel-saving potential for waste heat recovery system integrated with hybrid electric vehicle

Hybrid electric vehicles (HEVs) with low fuel consumption, low emissions, and long driving range are the ideal transition models between conventional fuel vehicles and pure electric vehicles. The growing demand for increased vehicle efficiency has motivated the introduction of waste heat recovery (WHR) technology in the automotive industry, with the organic Rankine cycle (ORC) as the most promising measure for recycling waste energy. Currently, only a few studies have been conducted to couple HEV and WHR systems. These studies have mainly focused on the hybrid powertrain control strategy, but lack quantitative methods to comprehensively analyze the fuel-saving potential due to the WHR system. In this study, an HEV-WHR integrated system that includes a mechanism-based dynamic model of ORC and a hybrid diesel-electric truck model is established. Further, a quantitative evaluation method that simultaneously considers the negative integrated effects (increased vehicle weight and increased exhaust back pressure) and the positive impact values of the engine, motor, and WHR system on the fuel-saving potential is proposed. Finally, the influence of two environmental factors (wind speed and ambient temperature) on the fuel-saving performance is analyzed. The results reveal that under the standard highway driving cycle (HWY), the negative integrated effects reduce the ideal fuel-saving potential of the HEV-WHR system from 6.10% to 5.42%. However, the optimized performances of the engine, motor, and WHR system improve the fuel-saving rate by 0.39%, 1.81%, and 3.22%, respectively. The results also indicate that the fuel-saving potential increases from 1.62% to 8.60% with increasing wind speed and decreases from 6.70% to 4.25% with increasing ambient temperature.     

Impact of powertrain hybridization on the performance and costs of a fuel cell electric vehicle

Battery Electric Vehicles (BEVs) and Fuel Cell Electric Vehicles (FCEVs) have gained attention due to the growing concern about air quality in large urban centers. Barriers such as high purchase price and the lack of a supply infrastructure delay the mass adoption of these vehicles. The current work uses the Advanced Vehicle Simulator (ADVISOR) to analyze the influence of the degree of hybridization (DOH) on the performance and total cost of an FCEV (Hyundai Nexo 2019 model). The costs and fuel economy results of the different configurations (different DOH) are compared to those of the original vehicle. The configuration with the highest degree of hybridization (DOH = 61.2%) showed an 8.3% increase in fuel economy and a total cost reduction of 13.2% compared to the original vehicle. In addition, the best vehicle configuration results are compared to a same-segment gasoline-internal combustion engine vehicle and the original Hyundai Nexo in different cost scenarios.     

Prediction of hot tearing susceptibility of direct chill casting of AA6111 alloys via finite element simulations

To predict hot tearing susceptibility (HTS) during solidification and improve the quality of Al alloy castings, constitutive equations for AA6111 alloys were developed using a direct finite element (FE) method. A hot tearing model was established for direct chill (DC) casting of industrial AA6111 alloys via coupling FE model and hot tearing criterion. By applying this model to real manufacture processes, the effects of casting speed, bottom cooling, secondary cooling, and geometric variations on the HTS were revealed. The results show that the HTS of the billet increases as the speed and billet radius increase, while it reduces as the interfacial heat transfer coefficient at the bottom or secondary water-cooling rate increases. This model shows the capabilities of incorporating maximum pore fraction in simulating hot tearing initiation, which will have a significant impact on optimizing casting conditions and chemistry for minimizing HTS and thus controlling the casting quality.     

钠碱法硫酸尾气处理装置改造的生产实践

介绍了新疆某公司钠碱法硫酸尾气处理装置的原理、运行状况及改造实践。针对排放尾气中颗粒物及硫酸雾2项指标达不到新疆地区工业污染物排放限值要求的问题,采取在脱硫塔后部增加1台湿式电除尘器的方法对该脱硫系统进行改造,改造后硫酸雾质量浓度在3 mg/m^3以下,颗粒物质量浓度在1 mg/m3以下,远低于排放限值的要求,达到了预期目标。     

底板带压开采工作面并行电透视探测技术应用研究

汾西矿务局水峪矿部分工作面现已面临带压开采问题，受下伏奥陶系灰岩水害影响，工作面安全回采过程中的防治水工作难度增加，尤其是带压开采工作面底板灰岩水的有效探测变得异常紧迫与重要。为了解决底板带压开采工作面富水区的探测问题，水峪矿引入了并行电透视技术，并对相应工作面进行了探测应用。并行电透视技术相对于传统音频电透视技术具有仪器智能化控制发射接收切换、一发射点并行对应多接收点、仪器智能快速高效跑极施工的3项技术优势，可体现应用现场施工高效、实际探测效果可靠的技术特点。经过对并行电透视技术及探测应用效果分析研究，证明该方法技术领先，现场施工高效，实际探测结果可靠，实用性强。     

求解带时间窗车辆路径问题的改进型烟花算法

针对带时间窗车辆路径问题,为寻求组合优化问题最优解,构建总运输成本最小数学模型。由于烟花算法搜索半径不能自适应调整,算法后期易陷入局部最优,故对爆炸算子进行改进,使最优烟花搜索半径自适应调整,增强后期局部搜索能力;同时利用分布式信息共享机制避免算法早熟并引入变异火花增强种群多样性。利用标准测试集进行验证后,结果表明该算法在求解带时间窗车辆路径问题时不仅具有可行性和有效性,并且收敛速度快、搜索质量高。     

Interfacial energy for solutions of nanoparticles,surfactants, and electrolytes

The addition of surfactants to modify the surface property of nanoparticles (NPs) from hydrophilic to hydrophobic also enhances their interfacial properties. Several approaches were previously proposed to calculate the surface tension/interfacial tension (IFT) for different systems in the presence of NPs, surfactants, and electrolytes. However, most of these approaches are indirect and require several measured parameters. Therefore, a mathematical model is developed here to calculate the surface tension/IFT for these systems. The developed model takes into account the cohesive energy due to the interaction of the surfactant CH₂ groups, the electric double layer effect due to the interaction among the ions of NPs, surfactants, and electrolytes, and the dipole–dipole interaction of NPs and electrolytes. The developed model is compared and validated with the laboratory experimental data in literature. The results reveal further understanding of the mechanisms involved in stabilization of oil/water emulsion in the presence of NPs, surfactants, and electrolytes.