共沉淀法制备花状NiCo2O4及其吸波性能的研究

通过共沉淀法制备花状NiCo₂O₄吸波材料，利用XRD、FTIR、BET、XPS和SEM等方式表征了样品成分及形貌特征，将不同煅烧温度（300、400、500、600、700 ℃）的产物利用矢量网络分析仪通过同轴测试法模拟了不同厚度下的吸波性能。结果表明：400 ℃煅烧样品在反射损耗值、吸收带宽以及样品厚度都表现出较好的性能，当厚度为1.5 mm时，在14.32 GHz处吸波材料达到最大的吸收损耗值为-43.71 dB，有效吸收带宽为4.48 GHz （12.08~16.56 GHz），可以预见镍钴基吸波材料具有很大的潜力。     

Study of aerosol anomaly associated with large earthquakes (M>6)

We present the variation of unusual atmospheric phenomena, aerosols, to understand the preseismic irregularities for two major earthquakes in Japan. We consider aerosol optical depth and Angstrom exponent data retrieved from the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument onboard the Terra satellite to establish possible connections between earthquakes and the generation of aerosols. Variation of the aerosol parameters shows significant changes before the April 15, 2016, Kumamoto earthquake ($M=7.0,h=10$ km) and the November 21, 2016, Fukushima earthquake ($M=6.9$ and $h=9$ km), where M indicates the Richter magnitude and h indicates the focal depth. To identify the source of the aerosol particles, we use the Hybrid Single-Particle Lagrangian Integrated Trajectory model (HYSPLIT-4). This model uses both Lagrangian and Eulerian approaches to compute trajectories and establish a source-receptor relationship. We compute backward trajectories to check whether the aerosol generated near the epicenter is due to the preseismic processes or is transported from other areas. From our results, we conclude the fine-mode aerosols are generated in the vicinity of the epicenter, 3–7 days before the earthquakes.     

民用飞机刹车系统CCAR 25.735条款适航研究

介绍了民用飞机适航规章CCAR-25-R4最新版并与前一版本R3版在刹车系统主条款25.735条进行对比分析，详细解释了R4版与R3版的不同之处及更改原因，阐述了R4版735条的详细要求，提供了刹车系统的适航思路及符合性方法建议。最后进行了小结并提出了下一步目标。     

TC4钛合金切削中切屑塑性变形分析

对TC4钛合金切削过程中锯齿形切屑形成过程和切削力的关系进行了实验研究,并对锯齿形切屑形成中微观塑性变形区进行了分析。结果表明:当切削速度大于48.75 m/min时,切屑由带状转变为锯齿形。锯齿形切屑的形成导致了切削过程中切削力的波动变化,切削力与切屑的锯齿形变化规律一致,锯齿形切屑形成中塑性变形区的宽度随切削速度的增加而减小。     

Improving performance of macro electrolyte jet machining of TC4 titanium alloy: Experimental and numerical studies

Electrolyte jet machining (EJM) is a promising method for shaping titanium alloys due to its lack of tool wear, thermal and residual stress, and cracks and burrs. Recently, macro-EJM has attracted increasing attention for its high efficiency in machining wide grooves or planes. However, macro-EJM generates large amounts of electrolytic products, thereby increasing the difficulty of rapid product removal with a standard tool and reducing the surface quality. Therefore, for enhanced product transport, a novel tool with a back inclined end face was proposed for macro-EJM of TC4 titanium alloy. For comparison, also proposed were ones with a standard flat end face, a front inclined end face, and both front and back inclined end faces. The flow field distributions of all proposed tools were simulated numerically, and experiments were also conducted to validate the simulation results. The results show that one with a 5° back inclined end face can decrease the low-velocity flow zone in the machining area and increase the high-velocity flow zone at the back end of tool, thereby promoting rapid product removal. A relatively smooth bright-white groove surface was obtained. The same tool also resulted in the highest machining depth and material removal rate among the tested ones. In addition, rapid product removal was beneficial to the subsequent processing. Because of its rapid product removal, the machining depth and material removal rate during deep groove machining using the tool with a 5° back inclined end face were respectively 7% and 14% higher than those produced using a standard one. Moreover, the lowest bottom height difference of 0.027 mm can be obtained when the step-over value was 8.2 mm, and a plane with a depth of 0.285 mm and a bottom height difference of 0.03 mm was fabricated using the tool with a 5° back inclined end face.