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141.
Phase change analysis of an underwater glider propelled by the ocean's thermal energy 总被引:1,自引:0,他引:1
KONG Qiao-ling MA Jie 《船舶与海洋工程学报》2007,6(4):37-43
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. 相似文献
142.
Peng Tao Jin YueBo 《中国水运》2007,5(9):219-220
介绍了螺旋折流板列管式换热器的结构特点,对其流动换热的机理以及影响因素作了分析,并的对其在轮机工程中的适用问题提出了看法。 相似文献
143.
144.
基于IEEE802.11b协议的无线网络组建 总被引:1,自引:0,他引:1
万钢 《武汉船舶职业技术学院学报》2006,5(5):69-72
介绍了基于IEEE802.11b协议的低成本双机互联无线网络的组建方法。基于该方法组建的双机无线网络成本低廉,同时实现计算机的文件共享、打印机共享和Internet连接共享。 相似文献
145.
146.
C. -H. Chien J. -Y. Jang Y. -H. Chen S. -C. Wu 《International Journal of Automotive Technology》2008,9(4):437-445
People use cars so frequently that they always consider the air-conditioning, and thermal comfort of the driver and passenger
when buying a new car. Therefore accurate simulation of the thermal performance of automobile air conditioners to improve
human comfort has become increasingly important. In order to improve the thermal comfort of passengers, 3-D flow motion and
thermal behavior within vehicles must be analyzed. In this paper, a numerical simulation was used to investigate thermal behavior
in a vehicle. Because air temperature at an air vent is related to the cooling capacity of the air conditioner, the cooling
capacity was calculated using ɛ-NTU (effective number of transfer unit) theoretical equations. Using the air temperature relationship between inlet and outlet
vents as boundary conditions, a 3-D unsteady κ-ɛ turbulent model was used to give a transient analysis simulation of the temperature field and flow conditions in a vehicle’s
passenger cabin. Cooling cycle analysis and conjugate heat transfer analysis at the inside surface of the cabin’s ceiling,
floor and sides were also considered. The predicted temperature distributions in the vehicles passenger cabin were in good
agreement with those obtained experimentally. 相似文献
147.
Most routing protocols for sensor networks try to extend network lifetime by minimizing the energy consumption, but have not taken the network reliability into account. An energy-aware, load-balancing and fault-tolerant routing scheme, termed as ELFR was propsed to adapt to the harsh environment. First a network robustness model was presented. Based on this model, the route discovery phase was designed to make the sensors to construct into a hop-leveled network which is mesh structure. A cross-layer design was adopted to measure the transmission delay so as to detect the failed nodes. The routing scheme works with acknowledge (ACK) feedback mechanism to transfer control messages to avoid producing extra control overhead messages. When nodes fail, the new healthy paths will be selected locally without rerouting. Simulation results show that our scheme is much robust, and it achieves better energy efficiency, load balancing and maintains good end-to-end delay. 相似文献
148.
149.
为更有效地设计隧道照明,针对隧道LED照明模拟设计欠缺的现状,基于Zigbee无线通信研发了隧道LED照明模拟控制系统,提出并设计了车载照度采集装置,实现对隧道内亮度的连续检测。实验分析表明:车载照度采集装置误差在-5.69%~3.06%之间,隧道模型设计亮度误差在-4.49%~5.57%之间,具有较高的可靠性。最后,研究成果已应用到隧道照明改造的模拟设计中,改造后节能百分比达53.6%。 相似文献
150.
李晓梅 《兰州交通大学学报》2015,(2):82-84
根据二语习得的理论,母语和目的语之间是存在迁移现象的。由于方言负迁移的现象普遍存在,中国不同地区的学生在说英语时难免会受到方言的影响。本文拟从语音理论和迁移理论出发,研究甘肃地区的英语学习者语音发音中存在的主要问题,并探讨行之有效的语音教学方法。 相似文献