焊接热源有效利用率的测试计算法

给出实际热输入值是正确求解焊接热弹塑性问题和焊接残余应力与变形问题的前提;因而,准确地确定热源有效利用率η,在焊接力学的发展中是一个急待解决的命题。本文推荐采用的“测试计算法”提供了一个能够准确、简捷地求得η值的新途径。引入被焊材料的熔化潜热系数后,给出了线热源加热焊缝金属至熔化温度(处于液态)时的实际热有效利用率ηt 的表达式。在四种不同类型的薄板材料上进行了钨极氩弧焊试验,测试计算结果与理论值相符合。理论推导与试验结果均证明,形成焊缝所需要的线能量的无量纲数值等于焊缝金属熔化热有效利用率ηt 的倒数。文中给出的焊接规范参数选择原则也适用于符合线热源条件的其它熔焊热源。η值不但与焊接工艺方法、规范参数有关,而且也随被焊材料的热物理特性不同而异。     

挤压变形对Mg95Zn4.3Y0.7合金组织和性能的影响

研究了在250℃、不同挤压比下挤压变形对Mg95 Zn4.3 Y0.7合金组织及性能的影响。结果表明，Mg95 Zn4.3 Y0.7经过挤压变形后，合金中晶界处的共晶相破碎，弥散分布至晶粒内部，并且晶粒显著细化。同时，随着挤压比的增大，晶粒细化程度增加，合金的力学性能单调增加。当挤压比为16时，合金晶粒尺寸为5-8μm，抗拉强度为288.9MPa，显微硬度HV值为117.8。     

长轴表面激光淬火变形与控制

应用激光淬火强化技术控制长轴的淬火变形，分析了激光淬火变形的原因和影响因素。研究结果表明，激光淬火不仅可使长轴振摆变形量控制在很小的范围内，而且可将已变形的长轴校直到很高的精度。     

Ensemble deep transfer learning driven by multisensor signals for the fault diagnosis of bevel-gear cross-operation conditions

The existing intelligent fault diagnosis techniques of bevel gear focus on single-sensor signal analysis under the steady operation condition. In this study, a new method is proposed based on ensemble deep transfer learning and multisensor signals to enhance the fault diagnosis adaptability and reliability of bevel gear under various operation conditions. First, a novel stacked autoencoder(NSAE) is constructed using a denoising autoencoder, batch normalization, and the Swish activation function. Second, a series of source-domain NSAEs with multisensor vibration signals is pretrained. Third, the good model parameters provided by the source-domain NSAEs are transferred to initialize the corresponding target-domain NSAEs. Finally, a modified voting fusion strategy is designed to obtain a comprehensive result. The multisensor signals collected under the different operation conditions of bevel gear are used to verify the proposed method. The comparison results show that the proposed method can diagnose different faults in an accurate and stable manner using only one target-domain sample, thereby outperforming the existing methods.     

PAN/FPU Composite Nanofiber Membrane with Superhydrophobic and Superoleophobic Surface as a Filter Element for High-Efficiency Protective Masks

Recently, because of the outbreak of COVID-19, the demand for various types of filter elements in protective materials has increased globally. Furthermore, new requirements for the filtration performance of PM2.5 liquid (oil) particles have been put forward. In this work, Superhydrophobic and superoleophobic composite nanofibers with excellent filtration capacity for oil and salt particles are developed through the modification of polyacrylonitrile (PAN) by fluoro-polyurethane (FPU) doping. The results show that the PAN/FPU composite nanofibers doped with 9 wt% FPU has a uniform fiber morphology with a diameter of 240 ± 30 nm. Compared to the pure PAN nanofibers, the water-based contact angle of PAN/FPU increases from 90 ± 5° to 151 ± 5°, and the oil-based contact angle increases from 58 ± 2° to 152 ± 3°. Importantly, at a high flow rate of 95 L min⁻¹, the filtration efficiency of the PAN/FPU nanofiber membrane for 0.3 µm oil particles increases from 92 ± 1% to 99.2 ± 0.1%. After cyclic loading, the filtration efficiency of 0.3 µm oil particles remains above 98%. Meanwhile, the filtration efficiency for 0.3 µm salt particles remains at 98.23 ± 0.1%. The PAN/FPU nanofiber membrane developed in this work is effective in applications and has good market prospects as a protective filtration material.     

Preparation and Bioactivity of Iridium(III) Phenanthroline Complexes with Halide Ions and Pyridine Leaving Groups

A series of half-sandwich structural iridium(III) phenanthroline (Phen) complexes with halide ions (Cl⁻, Br⁻, I⁻) and pyridine leaving groups ([(η⁵-Cp^X)Ir(Phen)Z](PF₆)_n, Cp^x: electron-rich cyclopentadienyl group, Z: leaving group) have been prepared. Target complexes, especially the Cp^xbiph (biphenyl-substituted cyclopentadienyl)-based one, showed favourable anticancer activity against human lung cancer (A549) cells; the best one ( Ir8 ) was almost five times that of cisplatin under the same conditions. Compared with complexes involving halide ion leaving groups, the pyridine-based one did not display hydrolysis but effectively caused lysosomal damage, leading to accumulation in the cytosol, inducing an increase in the level of intracellular reactive oxygen species and apoptosis; this indicated an anticancer mechanism of oxidation. Additionally, these complexes could bind to serum albumin through a static quenching mechanism. The data highlight the potential value of half-sandwich iridium(III) phenanthroline complexes as anticancer drugs.     

DMFC阳极催化剂用GRQD-NiCo2O4复合物的制备与电催化活性分析

采用水热法制备GRQD-NiCo₂O₄复合物,利用XRD、SEM及TEM分析其微结构,并探讨其作为DMFC阳极催化剂使用时的电化学性能。微结构分析表明所得GRQD-NiCo₂O₄复合物皆为具NiCo₂O₄单一相的尖晶石结构,且GRQD质量浓度高于0.25 g/mL后表面形貌将转变GRQD与NiCo₂O₄相互结合的状态。电化学分析表明添加GRQD可有效增强NiCo₂O₄的导电性并提升其电化学稳定性,其中GRQD质量浓度为0.25 g/mL时所得样品经500次循环测试后电流密度约为77.5 A/g,与循环5次后相比其电流密度剩余量最大（约为69.7%）,该样品作为DMFC阳极催化剂使用时性价比最佳。     

1 250 mm五机架六辊冷连轧工艺控制系统核心技术

简要介绍了自主设计制造、具有完全自主知识产权的1 250 mm五机架六辊冷连轧产线工艺及设备特点。重点阐述了冷连轧工艺控制系统的硬件配置、软件架构及核心技术。采用基于简易有限元的轧制力模型及基于成本函数的多目标负荷分配模型，实现了高精度的轧制规程计算。开发了原料板快速启车技术与板形多变量综合最优控制技术，实现了冷轧产品的尺寸精准控制。现场实际应用效果表明，机组稳定运行率达到99.8%以上，不同规格的产品厚度控制精度均达到±0.8%以内，板形控制精度均达到5I以内。     

助卷辊电液伺服系统相关辨识法研究

用相关辨识法分析了卷取机助卷辊电液伺服系统的频率特性 ,采用 Levy法求出系统的传递函数 ,并且给出该系统频率特性相关参数。     

磷钨酸催化合成癸二酸二丁酯

磷钨酸作为癸二酸和正丁醇的酯化催化剂，性能优于硫酸。本文探讨并找到了其较好的反应条件，酯化率达99．5％。