基于新工科背景"数字测图原理与方法"课程教学改革

新工科建设是基于国家战略发展新需求而提出的我国高等工程教育改革的新方向.基于新工科建设背景,文章以"数字测图原理与方法"为研究对象,立足工程教育认证理念,分析测绘工程专业课程体系面临的问题,对课程建设、教学改革进行研究探索.采取"线上线下混合教学、项目案例教学、综合考核"教学模式,课程思政引导、学科竞赛引领的自主学习模式,为测绘工程专业人才培养体系的持续改进优化提供有效支撑.     

熔剂净化对Al－4．5wt％Cu合金过冷及组织的影响

采用盐类熔剂对大体积Ａｌ－４．５ｗｔ％Ｃｕ合金进行净化处理，研究了熔剂净化对Ａｌ－４．５ｗｔ％Ｃｕ合金过冷及组织的影响。通过大量的实验研究证明：粘性熔剂更能有效地去除合金中的异质核心，使合金获得较大的过冷度；随着过冷度的增大，合金的宏观组织由细小的等轴晶逐渐过渡到粗大的柱状晶，其临界转变过冷度为４０℃；二次枝晶间距随过冷度的增大而增大，其转变过冷度为５０℃。     

Simulation study on the gasification process of Ningdong coal with iron-based oxygen carrier

Chemical looping gasification (CLG) of Ningdong coal by using Fe₂O₃ as the oxygen carriers (OCs) was studied, and the gasification characteristics were obtained. A computation fluid dynamics (CFD) model based on Eulerian‐-Lagrangian multiphase framework was established, and a numerical simulation the coal chemical looping gasification processes in fuel reactor (FR) was investigated. In addition, the heterogeneous reactions, homogeneous reactions and Fe₂O₃ oxygen carriers' reduction reactions were considered in the gasification process. The characteristics of gas flow and gasification in the FR were analyzed and it was found that the experiment results were consistent with the simulation values. The results show that when the O/C mole rate was 0.5:1, the gasification temperature was 900 ℃ and the water vapor volume flow rate was 2.2 ml·min^-1, the mole fraction of syngas reached a maximum value of the experimental result and simulation value were 71.5% and 70.2%, respectively. When the O/C mole rate was 0.5:1, the gasification temperature was 900 ℃, and the water vapor volume flow was 1.8 ml·min^-1; the gasification efficiency reached the maximum value was 62.2%, and the maximum carbon conversion rate was 84.0%.     

Fouling characteristics of 90° elbow in high salinity wastewater from coal chemical industry

Due to the high salt content of coal chemical wastewater, pipeline fouling often occurs during wastewater treatment. Fouling will cause the diameter of the pipe to shrink or even block, which is not conducive to the safe and stable operation of the wastewater treatment process. In this paper, the experimental device was designed by using FLUENT software and the fouling deposition mechanisms at different flow velocities and different positions in a 90 deg bend were studied. The experimental results show that when the flow velocity is between 0.2 m·s~(-1) and 0.3 m·s~(-1), the thickness of fouling layer was positively correlated with the flow velocity; when the flow velocity is equal to 0.4 m·s~(-1), the formation of fouling is the most serious; when the flow velocity is between 0.4 m·s~(-1) and 0.7 m·s~(-1), the thickness of fouling layer was negative correlation with the flow velocity; with the increase of inlet velocity, the time for sediment point to develop into sediment surface is shortened. The fouling layer is easy to fall off because of the large shear force on the wall surface of the inner bend of the 90° elbow, so the density of sediment at this position is high.     

基于WNN与FCM的电动汽车动态充电负荷预测方法

随着电动汽车动态无线充电(EV-DWC)技术的发展,针对目前EV-DWC负荷建模理论工作不全面的现状,以交通流量作为影响充电负荷的主要因素,以天气、典型日期、季节等因素为次要影响因素,根据路况建立负荷模型,通过电动汽车型号和状态的聚类不同对汽车分配不同的功率,完成动态充电负荷的建立。采用小波神经网络(WNN)对时序信息进行处理预测,再同误差反向传播神经网络(BPNN)相结合预测充电道路上的车流,短期车流预测精度为85%,用模糊C聚类(FCM)算法对电动汽车的充电类型以及该类型所对应的充电功率进行划分,将进入充电道路的电动汽车分为7种类型。根据各种充电类型分配相应的充电功率,完成日负荷建模。     

Importance of Low-Temperature Melt-Mixing on the Construction of Stereocomplex Crystallites with Superior Nucleation Efficiency in Asymmetric Poly(l-lactide)/Poly(d-lactide) Blends

The nucleation efficiency (NE) of stereocomplex crystallites (SCs) formed in asymmetric poly(L-lactide)/poly(D-lactide) (PLLA/PDLA) blends is generally unsatisfactory because the competition between stereocomplexation and chain mixing involved in the melt-mixing process can cause low formation efficiency and even severe aggregation of SCs. Herein, it is attempted to achieve high-efficient formation of finely dispersed SCs particles by designing a unique melt-mixing procedure, where the mixing of PLLA with 0.75 wt% PDLA is first performed at elevated temperatures (far above the melting temperature of SCs) to allow the homogeneous mixing of PLLA/PDLA chains and then at a low temperature (slightly above that of homocrystallites) to permit the full stereocomplexation of the premixed chains. It is found that the SCs formed in the blends exhibit unexpectedly low NEs (e.g., 54.5%), much inferior to that (73.6%) in the counterpart without undergoing premixing. This is because the introduction of premixing leads to a remarkable deterioration in the amount of SCs particles formed, despite decreased particle size, highlighting that the direct mixing at low temperatures of 170–180 °C (about 20–30 °C lower than that used in common melt-processing of PLA) is more effective for the construction of SCs with superior NE. The mechanisms for these striking findings are discussed.     

Stereocomplex Crystallization Induced Significant Improvement in Transparency and Stiffness–Toughness Performance of Core-Shell Rubber Nanoparticles Toughened Poly(l-lactide) Blends

Toughening modification of poly(l -lactide) (PLLA) with rubber particles is often realized at the cost of transparency, mechanical strength, and modulus because high rubber loadings are generally required for toughening. In this work, a promising strategy to simultaneously improve the transparency and stiffness–toughness performance of poly(butyl acrylate)-poly(methyl methacrylate) (BAMMA) core-shell rubber nanoparticles toughened PLLA blends by utilizing the stereocomplex (SC) crystallization between PLLA and poly(d -lactide) (PDLA) is devised. The results reveal that the construction of SC crystallites in PLLA matrix via melt-mixing PLLA/BAMMA blends with PDLA can prevent BAMMA nanoparticles from aggregation and promote them to form network-like structure at lower contents. As a result, not only higher toughening efficiency with less rubber contents but also superior transparency is achieved in the PLLA/PDLA/BAMMA blends as compared with the PLLA/BAMMA ones where large aggregated BAMMA clusters are formed. Moreover, the outstanding reinforcement of SC crystallites network for PLLA can impart an enhanced tensile strength and modulus to PLLA/PDLA/BAMMA blends, thus improving the stiffness–toughness performance of PLLA/PDLA/BAMMA blends to a higher degree. This work demonstrates that SC crystallization is a promising solution to solve the contradiction between transparency and mechanical properties and then obtain superior comprehensive performances in rubber toughened PLLA blends.     

Influences of mullite fibers on mechanical and thermal properties of silica-based ceramic cores

Mullite fibers composite silica-based ceramic cores were successfully prepared by injection molding. The effects of mullite fibers on the mechanical and thermal properties of ceramic cores were investigated. The results indicated that the linear shrinkage was significantly decreased and the porosity was gradually increased with the increase of mullite fibers. In addition, the flexural strength for the room temperature and the simulated casting temperature of 1500°C was increased to a maximum value when the content of mullite fibers was about 1 wt.%, and then decreased with the increase of mullite fibers. The mullite fibers of 1 wt.% presented excellent mechanical properties with a linear shrinkage of .65%, a porosity of 6.96%, and a flexural strength of 17 MPa at room temperature and 34.83 MPa at the simulated casting temperature of 1500°C. Besides, the change in microstructure and properties in various contents of mullite fibers were analyzed.     

非贵金属电解水催化剂改性研究进展

氢能作为理想的二次能源,具有能量密度高、清洁无污染等特点,在能源转型过程中将发挥极为重要的作用。电解水制氢被认为是获取氢能最有潜力的绿色工艺,而高效电催化剂是制约电解水制氢快速发展的关键。贵金属催化剂具有优良的电催化性能,但由于成本和储量问题严重限制其推广应用,因而开发低成本高活性的非贵金属催化剂逐渐成为研究热点。为提高非贵金属催化剂的电催化性能,需要对其进行一系列的改性优化工作。综述了近几年国内外非贵金属电解水催化剂的改性研究进展,详细介绍了几何构造（一维、二维、三维结构）和电子调控（组成优化、晶面调控、缺陷构造、杂原子掺杂等）两种非贵金属催化剂的改性方法,并对今后非贵金属电解水催化剂改性发展方向进行了展望。     

自动壳封焊机焊缝位置控制的实验研究

为解决自动壳封焊机机械凸轮式仿形的缺点，提出了基于电子凸轮的控制方案，为实现电子凸轮控制方案，在焊接轨迹形成分析的基础上，建立了焊枪位置控制的数学模型，改进后的自动焊机焊接试验表明，焊接位置误差较小，可以满足生产的需要。