矩阵变换器的MATLAB仿真研究

矩阵变换器是一种新型的电力变换器,直接实现交流到交流的变频与变压.与典型的交-直-交变换器相比,具有动态响应快,能有效抑制谐波,可实现对电压幅值、频率、功率因素角等独立可调等优点.MATLAB是一种功能强大的仿真软件,本文主要是利用MATLAB的SIMULINK对3×3相矩阵变换器进行原理仿真.     

拱上建筑加载顺序对主拱圈的影响

以钢管混凝土肋拱桥为例,根据结构有限元理论建立空间分析的有限元模型,研究了拱上建筑加载顺序对主拱圈变形及受力的影响,从而选择更为安全的拱上建筑施工加载顺序.     

Application of the VOF method based on unstructured quadrilateral mesh

To simulate two-dimensional free-surface flows with complex boundaries directly and accurately, a novel VOF (Volume-of-fluid) method based on unstructured quadrilateral mesh is presented. Without introducing any complicated boundary treatment or artificial diffusion, this method treated curved boundaries directly by utilizing the inherent merit of unstructured mesh in fitting curves. The PLIC (Piecewise Linear Interface Calculation) method was adopted to obtain a second-order accurate linearized reconstruction approximation and the MLER (Modified Lagrangian-Eulerian Re-map) method was introduced to advect fluid volumes on unstructured mesh. Moreover, an analytical relation for the interface’s line constant vs. the volume clipped by the interface was developed so as to improve the method’s efficiency. To validate this method, a comprehensive series of large straining advection tests were performed. Numerical results provide convincing evidences for the method’s high volume conservative accuracy and second-order shape error convergence rate. Also, a dramatic improvement on computational accuracy over its unstructured triangular mesh counterpart is checked.     

八种方法可帮你摆脱油耗猛增

一、适时为轮胎充足气在行驶中发现爱车的滑行距离明显减少。这时车主应该检查一下轮胎的气压是否合乎气压标准。若轮胎充气不足,耗油量也会增加。所以,适时为轮胎充足气很重要。二、必要时可更换新的轮胎检查轮胎的磨损程度。如果轮胎磨损严重时,就会经常出现打滑现象,增加耗油量。所以,必要时可更换新的轮胎。三、检修轴承及刹车系统在行驶中或启动时发现车轮有异常响声,要及时检查轴承及刹车系统     

极地船用FH40低温高强钢焊接工艺

以不同厚度规格的极地船用FH40低温高强钢为研究对象,分别采用焊条电弧焊（Shielded Metal Arc Welding,SMAW）、CO2气体保护药芯焊丝电弧焊（CO2 Gas Shielded Flux-Cored Arc Welding,FCAW-CO2）、埋弧焊（Submerged Arc Welding,SAW）等3种方法进行工艺试验。结果表明：焊接接头符合相应规范要求,力学性能指标符合设计要求。试验确定的焊接工艺参数可为新型极地船建造提供指导。     

崇明生态清洁小流域治理浅析

为实践治水新理念,打造河长制、湖长制水生态环境治理的升级版,促进地区人居环境改善和经济社会协调发展,上海市全面开展生态清洁小流域建设。本文尝试通过研究崇明地区生态清洁小流域的现状问题,分析崇明生态清洁小流域生态建设中需要采取的生态措施,为上海市清洁小流域建设提供新的参考。     

反射波法测桩之桩底反射分析

在低应变反射波法动力测试中，在工地现场采得并准确差别桩底反射信号一直是基桩检测人员的最主要判释。通过对不同桩型及复杂地层中桩底反射的认识，可以帮助检测人员积累工程桩检测的经验，有助于提高检测水平。