不同生态系统CO2通量和浓度特征分析研究

本文利用1993～1994年日本国家农业环境研究所与中国科学院沙漠研究所合作在内蒙古奈曼地区实测的7种不同生态系统（沙丘、轻度放牧草原、中度放牧草原、重度放牧草原、无放牧草原、玉米田和大豆田）的净辐射、土壤热通量、两个高度的CO2浓度、温度、湿度和风速等资料，采用空气动力学方法，计算了CO2通量及其与环境和人为干扰因子的关系，并分析了不同下垫面的光合作用特征. 结果表明：各种下垫面CO2通量的共同特点是：在白天，CO2通量和梯度的输送方向是从大气向植被，在中午（11～13时）输送达到负的最大值； 在夜间，CO2通量和梯度输送方向与白天相反，是从植被向大气，在早晨（3～5时）达到正的最大值. 植被覆盖率及生物量不同的下垫面光合作用强度有明显差异，天气状况对光合作用也有一定影响.     

Predicting the capability-polar-plots for dynamic positioning systems for offshore platforms using artificial neural networks

As the capability of polar plots becomes better understood, improved dynamic positioning (DP) systems are possible as the control algorithms greatly depend on the accuracy of the aerodynamic and hydrodynamic models. The measurements and estimation of the environmental disturbances have an important role in the optimal design and selection of a DP system for offshore platforms. The main objective of this work is to present a new method of predicting the Capability-Polar-Plots for offshore platforms using the combination of the artificial neural networks (NNs) and the capability polar plots program (CPPP). The estimated results from a case study for a scientific drilling vessel are presented. A trained artificial NN is designed in this work and is able to predict the maximum wind speed at which the DP thrusters are able to maintain the offshore platform in a station-keeping mode in the field site. This prediction for the maximum wind speed will be a helpful tool for DP operators in managing station-keeping for offshore platforms in an emergency situation where the automation of the DP systems is disabled. It is obvious from the obtained results that the developed technique has potential for the estimation of the capability-polar-plots for offshore platforms. This tool would be suitable for DP operators to predict the maximum wind speed and direction in a very short period of time.     

南极中山站至Dome A考察断面湍流参数特征近地层湍流参数特征

利用南极中山站至Dome A考察断面上3个自动气象站2005～2007年的观测资料和2008年夏季在中山站附近冰盖获取的湍流观测资料,应用空气动力学方法和涡动相关法计算分析了中山站至Dome A断面上近地层各种湍流参数(感热通量,潜热通量,湍流温度、湿度和速度尺度,地表粗糙度,大气稳定度及动量输送系数)的季节变化、日变...     

On the use of the capability polar plots program for dynamic positioning systems for marine vessels

As the capability of polar plots becomes better understood, improved dynamic positioning (DP) systems are possible since the control algorithms greatly depend on the accuracy of the aerodynamic and hydrodynamic models. The measurements and estimation of the environmental disturbances have an important role in the optimal design and selection of a DP system for a marine vessel. The main objective of this work is to present a new software program capable of estimating the environmental forces, thrusters capability calculations, and capability polar plots for marine vessels. A flowchart illustrating the logic and data flow of a developed software program, the Capability Polar Plot Program (CPPP), and the estimated results for two case studies for a scientific drilling vessel and a survey vessel are presented. It is obvious from the obtained results that the developed program has a future potential for the estimation of the Capability Polar Plots for marine vessels. Moreover, the developed software program would be considered as a marine tool for the thrusters' selection and their configuration for marine vessels and floating production units for the Oil and Gas industries.     

阿克苏地区陆面蒸发的数值研究

本文的试验地区——塔里木盆地阿克苏地区气候干旱,雨量稀少。本文详细地介绍了在土壤湿润不足情况下蒸发的计算方法,但由于人工灌溉的原因使试验地区的地下水位上升到1.5m至2m,故对小麦地的蒸散研究,找们不能完全采用干旱情况下的蒸发公式来处理,本文采用大气湍流边界层阻力的空气动力学方法来计算,并通过与波文比方法的比较,给出了小麦地总蒸散的时变化状况。同时利用土壤分层模式,给出了土壤表层与深层的体积含水量的模拟结果,并与实测值进行了比较,发现二者是基本一致的。