TiO_2 sensitized by red-, green-, blue-emissive carbon dots for enhanced H_2 production

Carbon dots(Cdots) with a broad light absorption range could be a potential stable sensitizer for TiO_2,which is an excellent ultraviolet(UV) response photocatalyst. Herein, we systematically investigated the different color emissive Cdots-sensitized TiO_2 for H_2 production.Firstly, all kinds of Cdots enhanced the photocatalytic properties of TiO_2. All the Cdots-sensitized TiO_2 exhibits visible light H_2 production due to their absorption in the visible light region. The photocurrent and H_2 production amount display strong dependence on the light absorption range of Cdots. The blue-emissive Cdots endow the weak H_2 production rate due to its weak absorption in the visible light. The enhanced photocatalytic activities are mainly contributed to the strong light absorbance and high-efficient charge separation. The light absorption of green-and red-emissive Cdots is another main factor for the high catalytic activities besides charge separation.     

Global heat transfer model and dynamic ray tracing algorithm for complex multiple turbine blades of Ni-based superalloys in directional solidification process

High-quality solidification microstructure during directional solidification relies on precise temperature gradient control, so accurate calculation of the temperature field is critical. In this study, a 3D transient global heat transfer model of directional solidification by the Bridgman method based on the finite difference method is developed. The radiation heat in this model is calculated by the discrete transfer method, and a modified method of external surface area for irregular geometric models is proposed to reduce the zigzag shape caused by finite difference grids. Considering the radiative heat transfer between any surface elements of all materials in the directional solidification furnace, a dynamic ray tracing algorithm is developed to simulate the entire process of directional solidification. Then, the simulated results are compared with the theoretical results and experimental results, respectively. Finally, based on the present model and method, the simulation program developed is applied to the directional solidification of actual castings. The simulated results are in good agreement with the experimental results, which indicate that the model and method developed in this study is effective and practical.     

Improvement of “Pest” Resistance of MoSi2 Intermetallic Compound at 500 °C and 600 °C via Addition of B Fabricated by Spark Plasma Sintering

Oxidation of Metals - Mo–Si–B alloys were obtained by spark plasma sintering (SPS) using fine Mo–Si–B alloy powders with a particle size of 2.5 μm. The SPS...     

热浸镀镀层厚度的动态控制方程

利用简化的动态模型过程，推导了热浸镀条件下的膜层厚度控制方程，并通过实验手段对此方程作了验证.结果表明，该方程作为工程快速估算是可行的.      

钢轨踏面硬度在线非接触检测的研究

本文简述了电磁检测硬度的机理,利用电磁无损检测对钢轨双频淬火后的全长连续接触硬度检测进行测试研究,对钢轨纵向硬度的区分度已达铁道部部标准。对该研究成果转化为生产力进行了初步探讨。     

PSD动态响应建模方法的研究

提出热源法、离散近似法和有限元数值求解法3种PSD动态响应建模方法。对3种典型扫描轨迹仿真,得到不同时刻下光生电流值。结果表明,3种仿真结果完全吻合,有限元数值求解法比热源法适用范围广,比离散近似法具有方法简单、精度高等特点。     

汽车碰撞仿真研究中点焊连接关系的有限元模拟

在汽车有限元分析仿真计算中,结构中的点焊模拟一直是一个难以解决的问题。综合现有的模拟方法,对点焊提出了一种新的处理对策,即在焊接节点之间引入一个刚性梁单元,单元可承受拉伸力和剪切力,同时引入节点耦合技术,在计算焊接节点受力的时候将节点位移约束作为惩罚项添加进去。当单元内部受力超过点焊的实际承载能力时,焊点脱开,单元自动分解为两部分,且分解后自动进入接触搜寻处理系统。     

细直梁弯曲振动中的局域共振带隙

通过将声子晶体中的局域共振思想引入到细直梁的结构设计中,构造了一种具有低频局域共振带隙的周期结构细直梁。采用传递矩阵法计算了周期边界条件下该细直梁弯曲振动中的弹性波能带结构,计算结果表明该结构中存在低频弯曲振动带隙。采用有限元法计算了有限周期该细直梁的振动传输特性。以有机玻璃、橡胶/铜块振子构成的该局域共振细直梁为例,采用振动试验方法对其振动传输特性进行了测试。试验结果同理论及仿真结果相吻合。结果表明,局域共振结构可大大降低带隙频率,并增大带隙衰减。梁类结构是噪声及振动控制领域研究的主要对象之一,局域共振结构的应用为其提供了一种新的思路。     

谈建筑工程责任主体质量行为监管

文章就如何加强建筑工程责任主体质量监管,从勘察、设计、审图、施工、监理、检测、质量监督等方面做了较为详尽的阐述,对建筑业质量良性、可持续发展提出了切实可行的建议。     

模拟滤池自动加矾系统及其应用

介绍了模拟滤池自动加矾系统的组成及其在白洋湾水厂的应用情况。运行结果表明,该系统对原水流量及水质变化的适应性较强,滞后时间短(20～30 min),维护管理方便,能稳定控制出厂水水质,是比较理想的自动加矾控制系统。