三维管梁在汽车车身轻量化上的应用

在汽车轻量化趋势下,车身的轻量化依然十分重要.分别从国内外研究现状、结构设计、结构分析、质量对比分析几方面研究汽车上车身局部结构的轻量化.以本田思域2016款车身结构为研究对象,采用超高强钢辊压成型三维管梁替换车身A柱、车顶纵梁内部热成型冲压加强板.参考国标GB 26134—2010施加车顶抗压试验工况,保证优化后结构的车顶抗压性能与原结构相当,通过对比质量,得出集成三维管梁的新设计对车身的轻量化效果.研究结果表明：当三维管梁板材厚度为1 mm、材料为1 700 MPa马氏体钢时,新结构弯曲刚度和强度性能与原结构基本一致,且实现车身减重3.23 kg,轻量化效果明显.     

中式家具的演绎方略与流派倾向

在设计理论分析以及产品调查分析的基础上,概括现代中式家具的演绎方略,指出现代中式家具的流派倾向。现代中式家具设计方法体系由四个层次构成。现代中式家具的流派倾向主要有：新古典主义、新中式主义、后现代主义、新地方主义、新折中主义等。此外,将风格调查法、感性工学系统方法等引入,期望推动现代中式家具的理论创新和产品开发。     

近红外漫反射光谱检测损伤猕猴桃内部品质

研究贮藏期间损伤猕猴桃内部品质与其近红外漫反射光谱之间的关系。利用近红外光谱(12000～4000cm-1)技术和多元线性回归(multiple linear regression,MLR)、主成分回归(principal component regression,PCR)和偏最小二乘法(partial least squares,PLS)3种校正方法分别对损伤华优猕猴桃在2℃条件下贮藏4周期间的可溶性固形物含量、pH值和硬度进行定量分析;并对比吸光度原始光谱、一阶微分和二阶微分3种不同预处理方法的PLS模型校正结果。结果表明：一阶微分预处理方法时,应用PLS建立的可溶性固形物含量、pH值和硬度校正模型的效果最佳;预测集样品预测值与测量值之间的相关系数分别为0.812、0.703、0.919,预测均方根误差分别为0.749、0.153、1.700。说明应用近红外漫反射技术检测贮藏期间损伤猕猴桃的内部品质是可行的。     

Evolution of Raman spectra in nitrogen doped graphene

We present systematical Raman studies of nitrogen doped graphene (NG). Defective graphene by Ar⁺ ion bombardment was also studied for comparison. It was found that the defects/nitrogen dopants in NG are not homogenous. Our results also suggest that the G peak position and I_2D/I_G ratio cannot be simply used as fingerprint of doping concentration in NG. Both doping and compressive strain (as verified by transmission electron microscope) contribute to the shift of Raman peaks, while both doping and lattice defects contribute to the attenuation of 2D peak. Finally, the nature of defects in NG was probed and found that they are boundary defects. The detail analysis of the evolution of Raman spectra in NG would greatly help on the characterization and future application of this novel material.     

The effect of different rare earth oxides on mechanical and optical properties of hot pressed α/β-Sialon ceramics

The effect of Y₂O₃ and different REOs (La₂O₃, Nd₂O₃ and Er₂O₃) on mechanical and optical properties on Sialon ceramics was studied. Duplex α/β-Sialon ceramics were revealed by XRD patterns in sintered body. α-Sialon phase was increased abruptly with the addition of Y₂O₃ and different REOs. Mechanical properties were also increased with the addition of REOs as compared without REOs. The crystallization at the triple junction with Y₂O₃ added Sialon was observed by TEM, which may be related to the slow cooling rate in hot press sintering process. Slow cooling rate causes the crystallization of glassy phase that occurred in grain boundaries and triple junctions. Crystallization of glassy phase enhances the mechanical properties of the material. Y₂O₃ had the positive effect on densification and mechanical properties. Mg-α/β-Sialon composite shows higher light transmission in NIR region than any other composition but better mechanical properties were shown by other compositions.     

Multifunctional Co–B–O@CoxB catalysts for efficient hydrogen generation

The development of efficient and non-noble catalyst is of great significance to hydrogen generation techniques. Three surface-oxidized cobalt borides of Co–B–O@Co_xB (x = 0.5, 1 and 2) have been synthesized that can functionalize as active catalysts in both alkaline water electrolysis and the hydrolysis of sodium borohydride (NaBH₄) solution. It is discovered that oxidation layer and low boron content favor the oxygen evolution reaction (OER) activity of Co–B–O@Co_xB in alkaline water electrolysis. And surface-oxidized cobalt boride with low boron content is more active toward hydrolysis of NaBH₄ solution. An alkaline electrolyzer fabricated using the optimized electrodes of Co–B–O@CoB₂/Ni as cathode and Co–B–O@Co₂B/Ni as anode can deliver current density of 10 mA cm⁻² at 1.54 V for overall water splitting with satisfactory stability. Meanwhile, Co–B–O@Co₂B affords the highest hydrogen generation rate of 3.85 L min⁻¹ g⁻¹ for hydrolysis of NaBH₄ at 25 °C.     

Rolling-sliding wear on precipitation-hardened structures of an austenitic steel

Microstructures of equal and different hardnesses were produced by the aging of a precipitation-hardened austenitic steel. This material was used as a model for studying the effects of microstructural elements on rollingsliding wear on underaged and overaged or peak-aged and thermomechanically treated structures of equal hardness. The effect of different hardness was evaluated by comparing the underaged and peak-aged structures. Model wear tests were run using a marginally lubricated contact by using an Amsler A 135 tribometer. The results can be interpreted in terms of the resistance to plastic deformation and the crack formation and crack growth behaviour of the different structures. The latter was studied using the usual fatigue and crack growth tests.     

Microwave dielectric properties of Pb2MoO5 ceramic with ultra-low sintering temperature

Ultra-low firing microwave dielectric ceramic Pb₂MoO₅ with monoclinic structure was prepared via a conventional solid state reaction method. The sintering temperature ranged from 530 °C to 650 °C. The relative densities of the ceramic samples were about 97% when the sintering temperature was greater than 570 °C. The best microwave dielectric properties were obtained in the ceramic sintered at 610 °C for 2 h with a permittivity ∼19.1, a Q × f value about 21,960 GHz (at 7.461 GHz) and a temperature coefficient value of −60 ppm/°C. From the X-ray diffraction, backscattered electron image results of the co-fired samples with 30 wt% silver and aluminum additive, the Pb₂MoO₅ ceramics were found not to react with Ag and Al at 610 °C for 4 h. The microwave dielectric properties and ultra-low sintering temperature of Pb₂MoO₅ ceramic make it a promising candidate for low temperature co-fired ceramic applications.     

基于单片机的防酒后驾驶控制系统设计

针对酒后驾车导致交通事故频繁发生的现象,设计了一种能够防止酒后驾驶的自动控制系统。该系统由酒精传感器、AD574A转换器、89C51单片机控制器、语音报警、LED显示、继电器以及电机等构成。用DP-51PROC单片机综合仿真实验仪进行了仿真实验,结果表明：当酒精传感器检测出司机体内酒精浓度超标时,该系统能够自动切断汽车启动系统电源,实现其控制功能。     

冬枣压缩特性实验与计算仿真研究

为了研究冬枣果实在收获、分选、运输及贮藏过程的力学特性,对冬枣果实进行压缩实验和有限元仿真,分析不同成熟度白熟期和脆熟期冬枣在不同压缩方向下的弹性模量以及接触应力。压缩实验结果表明:白熟果实的破裂力大于脆熟果实;二者的压缩曲线相似,横向压缩曲线有较明显的生物屈服点,纵向压缩时没有明显的屈服点。横向压缩时,白熟果实的平均弹性模量计算值与仿真值分别为3.527 MPa和3.263 MPa,平均误差为11.38%;脆熟果实的平均弹性模量计算值与仿真值分别为3.131 MPa和2.877 MPa,平均误差分别为12.96%。纵向压缩时,白熟和脆熟果实的弹性模量计算值与仿真值平均误差分别为26.24%和27.66%。压缩应力云图显示:上压头接触面的最大应力大于与固定底板接触面的最大应力;横向压缩时,上下表面的接触应力呈现对称分布;相同的压缩方向,白熟果实的计算最大应力和仿真最大应力都大于脆熟果实;最大应力的计算值和仿真值的误差较大,最小平均误差为26.24%。研究结果可为冬枣运输、分级及贮藏过程中选择合适的包装设计和摆放方式提供理论参考。