Compressed earth blocks (CEB) are an alternative to cement blocks in the construction of wall masonry. However, the optimal architectural construction methods for adequate thermal comfort for occupants in hot and arid...Compressed earth blocks (CEB) are an alternative to cement blocks in the construction of wall masonry. However, the optimal architectural construction methods for adequate thermal comfort for occupants in hot and arid environments are not mastered. This article evaluates the influence of architectural and constructive modes of buildings made of CEB walls and concrete block walls, to optimize and compare their thermal comfort in the hot and dry tropical climate of Ouagadougou, Burkina Faso. Two identical pilot buildings whose envelopes are made of CEB and concrete blocks were monitored for this study. The thermal models of the pilot buildings were implemented in the SketchUp software using an extension of EnergyPlus. The models were empirically validated after calibration against measured thermal data from the buildings. The models were used to do a parametric analysis for optimization of the thermal performances by simulating plaster coatings on the exterior of walls, airtight openings and natural ventilation depending on external weather conditions. The results show that the CEB building displays 7016 hours of discomfort, equivalent to 80.1% of the time, and the concrete building displays 6948 hours of discomfort, equivalent to 79.3% of the time. The optimization by modifications reduced the discomfort to 2918 and 3125 hours respectively;i.e. equivalent to only 33.3% for the CEB building and 35.7% for the concrete building. More study should evaluate thermal optimizations in buildings in real time of usage such as residential buildings commonly used by the local middle class. The use of CEB as a construction material and passive means of improving thermal comfort is a suitable ecological and economical option to replace cementitious material.展开更多
基于中国保险汽车安全指数25%偏置碰撞工况,对某新能源汽车A柱的结构设计方案进行了研究。对比分析了基础结构、复合车身解决方案(Composite Body Solutions,CBS)胶块增强结构、热气胀形管梁增强结构对碰撞安全性的影响,介绍了CBS胶块...基于中国保险汽车安全指数25%偏置碰撞工况,对某新能源汽车A柱的结构设计方案进行了研究。对比分析了基础结构、复合车身解决方案(Composite Body Solutions,CBS)胶块增强结构、热气胀形管梁增强结构对碰撞安全性的影响,介绍了CBS胶块和热气胀形的制造工艺,并对热气胀形工艺进行了仿真分析,对比分析2种增强结构的工装投入和单件成本。研究发现,在均能实现小偏置碰撞安全性优秀等级的前提下,1500 MPa热气胀管梁方案在单件成本及轻量化方面比CBS胶块方案更具优势。展开更多
目的研究发动机缸体出现开裂失效原因。方法通过化学成分分析、力学性能分析、断口扫描分析、显微组织分析、能谱分析及低倍缺陷分析测试手段,对发动机缸体的开裂模式及失效原因进行分析。结果发动机缸体原材料中Si元素超标,导致晶界析...目的研究发动机缸体出现开裂失效原因。方法通过化学成分分析、力学性能分析、断口扫描分析、显微组织分析、能谱分析及低倍缺陷分析测试手段,对发动机缸体的开裂模式及失效原因进行分析。结果发动机缸体原材料中Si元素超标,导致晶界析出较多的Al Si Cu及Al2Cu脆性相,在开裂区域组织存在过热过烧现象,两个原因导致组织晶间结合力大大降低。同时,在开裂区域存在热节效应,低倍疏松和缩孔较集中的现象,为热裂纹形成及继续扩展提供了有利条件。结论通过不断改进设计工艺,控制原材料成分及调节浇注参数,大大减小了热裂纹出现概率,在后序批量生产中,未发现类似失效样件。展开更多
文摘Compressed earth blocks (CEB) are an alternative to cement blocks in the construction of wall masonry. However, the optimal architectural construction methods for adequate thermal comfort for occupants in hot and arid environments are not mastered. This article evaluates the influence of architectural and constructive modes of buildings made of CEB walls and concrete block walls, to optimize and compare their thermal comfort in the hot and dry tropical climate of Ouagadougou, Burkina Faso. Two identical pilot buildings whose envelopes are made of CEB and concrete blocks were monitored for this study. The thermal models of the pilot buildings were implemented in the SketchUp software using an extension of EnergyPlus. The models were empirically validated after calibration against measured thermal data from the buildings. The models were used to do a parametric analysis for optimization of the thermal performances by simulating plaster coatings on the exterior of walls, airtight openings and natural ventilation depending on external weather conditions. The results show that the CEB building displays 7016 hours of discomfort, equivalent to 80.1% of the time, and the concrete building displays 6948 hours of discomfort, equivalent to 79.3% of the time. The optimization by modifications reduced the discomfort to 2918 and 3125 hours respectively;i.e. equivalent to only 33.3% for the CEB building and 35.7% for the concrete building. More study should evaluate thermal optimizations in buildings in real time of usage such as residential buildings commonly used by the local middle class. The use of CEB as a construction material and passive means of improving thermal comfort is a suitable ecological and economical option to replace cementitious material.
文摘基于中国保险汽车安全指数25%偏置碰撞工况,对某新能源汽车A柱的结构设计方案进行了研究。对比分析了基础结构、复合车身解决方案(Composite Body Solutions,CBS)胶块增强结构、热气胀形管梁增强结构对碰撞安全性的影响,介绍了CBS胶块和热气胀形的制造工艺,并对热气胀形工艺进行了仿真分析,对比分析2种增强结构的工装投入和单件成本。研究发现,在均能实现小偏置碰撞安全性优秀等级的前提下,1500 MPa热气胀管梁方案在单件成本及轻量化方面比CBS胶块方案更具优势。
文摘目的研究发动机缸体出现开裂失效原因。方法通过化学成分分析、力学性能分析、断口扫描分析、显微组织分析、能谱分析及低倍缺陷分析测试手段,对发动机缸体的开裂模式及失效原因进行分析。结果发动机缸体原材料中Si元素超标,导致晶界析出较多的Al Si Cu及Al2Cu脆性相,在开裂区域组织存在过热过烧现象,两个原因导致组织晶间结合力大大降低。同时,在开裂区域存在热节效应,低倍疏松和缩孔较集中的现象,为热裂纹形成及继续扩展提供了有利条件。结论通过不断改进设计工艺,控制原材料成分及调节浇注参数,大大减小了热裂纹出现概率,在后序批量生产中,未发现类似失效样件。
