Phase change analysis of an underwater glider propelled by the ocean＇s thermal energy

The phase change characteristic of the power source of an underwater glider propelled by the ocean＇s thermal energy is the key factor in glider attitude control. A numerical model has been established based on the enthalpy method to analyze the phase change heat transfer process under convective boundary conditions. Phase change is not an isothermal process, but one that occurs at a range of temperature. The total melting time of the material is very sensitive to the surrounding temperature. When the temperature of the surroundings decreases 8 degrees, the total melting time increases 1.8 times. But variations in surrounding temperature have little effect on the initial temperature of phase change, and the slope of the temperature time history curve remains the same. However, the temperature at which phase change is completed decreases significantly. Our research shows that the phase change process is also affected by container size, boundary conditions, and the power source＇s cross sectional area. Materials stored in 3 cylindrical containers with a diameter of 38ram needed the shortest phase change time. Our conclusions should be helpful in effective design of underwater glider power systems.     

DF4B型机车传动轴断裂故障分析

针对DR4B型大修机车发生的多起传动轴断裂故障，介绍了故障情况，对传动轴的应力进行了初步的计算，分析了断裂的原因，并提出了相应的改进措施。     

沥青混合料的疲劳试验研究

已有文献表明加载频率对于疲劳寿命的影响较大，对于沥青砼．其影响可能更显著。根据沥青混合料的室内低频疲劳试验，运用耗散能理论，得到沥青混合料的低频疲劳规律。     

2005款日产Xterra

当1999年日产在美国推出首款Xterra．当年就售出10多万辆，在2000年Xterra更成为美国汽车市场十大畅销车之一，如今第二代Xterra正式登场，继续保持其旺盛的竞争力。     

双雄会——BMW 530i VS.VOLVO S80 2.6T

严冬已过，春光明媚，高尔夫球迷都在把握着球场的绿意而尽情享受挥杆的情趣，而作为汽车传媒的一分子，当然会在这大好时光中进行一场实力相当的较量，这次好不容才找到国产宝马530i和富豪S80 2.5T来做测试对比，除了满足读者的好奇心，也让我们对这两辆车有更深的了解。     

某沿海航行船舶螺旋桨的修理与检验

简要介绍某沿海航行船舶铜质螺旋桨的断裂特征和修理难度,重点阐述焊接修理方法的工艺要点,提出修理后检验工作应注意的问题。     

轿车电控燃油喷射系统故障检测技术方法

发动机电控燃油喷射系统以冷车起动性、怠速稳定性、增压压力、燃油经济性、废气排放控制性能优，被车用发动机广泛采用，但在汽车行驶中，由于受道路状况，环境气温、行驶条件、驾驶操作技能等因素影响难免发生各种故障，固而掌握电喷系统的故障检查方法尤为重要。为此介绍五种检查诊断技术方法，供检查各型电控轿车应用。其中控制单元各端口测量参数以富康轿车为例，其它车型亦可适用。