A novel fabrication route to microlaminated TiB2–NiAl composite sheet with {111}<μνω> texture by roll bonding and annealing treatment

Microlaminated TiB₂–NiAl composite sheet consisting of alternating NiAl and TiB₂-rich layers has been successfully fabricated. This fabrication method is composed of roll bonding for producing a multi-laminated Ni–(TiB₂/Al) sheet from Ni sheets and TiB₂/Al composite sheets, and of subsequent annealing treatment for forming a NiAl intermetallic phase by reaction diffusion. Microlaminated TiB₂–NiAl composite sheet obtained by this method exhibits strong {111}<μνω> texture. The formation mechanism of such texture by reaction diffusion has been discussed in view of texture inheritance. This method could utilize reaction diffusion to control texture component of materials, which is expected to provide an access to synthesize materials with texture for special requirement.     

Experimental evidence of structural evolution for TiB2 microcrystal under externally high stresses

The morphology evolution and defect structure of TiB₂ microcrystals treated under high stresses were analyzed using scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM). The results show that hexagonal TiB₂ with large particle size gradually evolved to flowerlike TiB₂ with small particle size under high stresses. The evolution process is mainly determined by the preferential cleavage of TiB₂ microcrystal, and the presence of multiple lamellar nanotwin and edge dislocation directly provides some evidence of plastic deformation and structural evolution. For clarity, a possible model is suggested based on the HTREM observation and the natural properties of TiB₂ materials to explain the process mechanism.     

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.     

生产系统人因失误评价技术研究

人因失误研究的最终目的是为了减少或者消除人误的再次发生。有效的人误分类是人因失误的关键问题之一,但目前还没有一种统一、固定的分类方法。首先,从人因失误的定义出发,给出了人因失误的工程分类方法和认知行为分类方法,并在此基础上,针对各类可控型人因失误,给出其综合评价指标;其次,借助人因失误综合评价指标的高低,能够有效地指导生产系统中人因失误控制活动;最后,结合人因失误分类方法对某汽车变速箱总成装配中的二轴分装中典型的人因失误进行了分类,首次对机械产品装配中的人因失误进行了分类和实例分析。实例证明,该方法能够客观、准确地为人因失误控制提供决策支持。     

光伏发电系统中铅酸电池充放电的分析

设计了光伏发电系统蓄电池充放电的拓扑电路和电流补偿电路。根据电池组的运行状态实时调整充电器的输出电压或电流,无需采集电池组内阻值,消除了由于计算电池组内阻值所带来的计算误差。建立并详细分析了铅酸电池充放电主电路拓扑电路的小信号模型,对电流反馈补偿网络进行了理论分析。通过仿真和实验结果分析表明,该拓扑电路的控制方法能满足蓄电池充电电压在一定范围平滑充电的要求,且在不同的阶段始终保持恒流充电。     

Numerical simulation of steel-plate strengthened concrete beam by a non-linear finite element method model

Strengthening with epoxy bonded steel plate is one of the most widely used techniques for flexural upgrading of reinforced concrete (RC) beams. However, debonding failure at the plate cut-off zone and or in the vicinity of flexure and shear cracks leads to catastrophic failure of the upgraded beams. This particular failure depends on several factors such as the distance of plate curtailment from the support, plate thickness and the provision of end anchors. Since the conventional beam theory cannot predict the debonding failure of such beams, a finite element model capable of predicting the overall behavior of strengthened beams including different failure modes accurately is developed. This paper presents the formulation of finite elements and material models and simulation results of some RC beams tested for flexural strengthening with epoxy bonded steel plates.     

Foreign direct investment and energy intensity in China: Firm-level evidence

Given the significance of energy use, which emits greenhouse gases and generates air pollution, decreasing energy intensity is considerably important for both China and the global environment. We employ a unique dataset of firm-level data on 13 cities in Jiangsu Province of China and investigate the relationship between FDI and energy intensity. Taking into account the heterogeneity characteristics of firms, we confirm a significant and negative coefficient of the FDI variable, which implies that FDI firms have lower energy intensity than their local counterparts. We introduce the interaction term of FDI and regional absorptive capacity, and the empirical results show that regions endowed with more absorptive capacity usually have lower energy intensity. Specifically, more spending on technology tends to narrow the technology gap between foreign and local firms, since local firms absorb international technology transfer more effectively and efficiently. Moreover, examining the cases of the textile and chemical industries, we find that FDI firms in the chemical industry have lower energy intensity than their local counterparts, while we observe no difference between FDI firms and non-FDI ones in the textile industry.