为了用水生生物生态状况评价乌江的水质情况,在乌江干、支流布置了14个采样断面,以Novak等的百分比模式相似性指数(Percent Model Affinity,PMA)对水电建设期间的乌江下游水质状态进行了评价,并与种类丰富度、EPT%和物种多样性指数相关...为了用水生生物生态状况评价乌江的水质情况,在乌江干、支流布置了14个采样断面,以Novak等的百分比模式相似性指数(Percent Model Affinity,PMA)对水电建设期间的乌江下游水质状态进行了评价,并与种类丰富度、EPT%和物种多样性指数相关性分析结果进行了比较。结果表明,支流除郁江水质一般(Moderate)外,其余断面水质处于良好(Good)状态,干流除彭水和洪渡较好外,其余断面水质一般(Moderate)。总体而言,支流水质要好于干流,导致乌江水质恶化的根源主要并不是有机污染,其原因可能与水电工程的建设活动及频繁航运有关。分析表明,百分比模式相似性指数与种类丰富度、EPT%和物种多样性指数相关性均达到显著水平。展开更多
In order to investigate wheel slip-sinkage problem, which is important for the design, control and simulation of lunar rovers, experiments were carried out with a wheel-soil interaction test system to measure the sink...In order to investigate wheel slip-sinkage problem, which is important for the design, control and simulation of lunar rovers, experiments were carried out with a wheel-soil interaction test system to measure the sinkage of three types of wheels in dimension with wheel lugs of different heights and numbers under a series of slip ratios (0-0.6). The curves of wheel sinkage versus slip ratio were obtained and it was found that the sinkage with slip ratio of 0.6 is 3-7 times of the static sinkage. Based on the experimental results, the slip-sinkage principle of lunar's rover lugged wheels (including the sinkage caused by longitudinal flow and side flow of soil, and soil digging of wheel lugs) was analyzed, and corresponding calculation equations were derived. All the factors that can cause slip sinkage were considered to improve the conventional wheel-soil interaction model, and a formula of changing the sinkage exponent with the slip ratio was established. Mathematical model for calculating the sinkage of wheel according to vertical load and slip ratio was developed. Calculation results show that this model can predict the slip-sinkage of wheel with high precision, making up the deficiency of Wong-Reece model that mainly reflects longitudinal slip-sinkage.展开更多
文摘为了用水生生物生态状况评价乌江的水质情况,在乌江干、支流布置了14个采样断面,以Novak等的百分比模式相似性指数(Percent Model Affinity,PMA)对水电建设期间的乌江下游水质状态进行了评价,并与种类丰富度、EPT%和物种多样性指数相关性分析结果进行了比较。结果表明,支流除郁江水质一般(Moderate)外,其余断面水质处于良好(Good)状态,干流除彭水和洪渡较好外,其余断面水质一般(Moderate)。总体而言,支流水质要好于干流,导致乌江水质恶化的根源主要并不是有机污染,其原因可能与水电工程的建设活动及频繁航运有关。分析表明,百分比模式相似性指数与种类丰富度、EPT%和物种多样性指数相关性均达到显著水平。
基金Project(50975059) supported by the National Natural Science Foundation of ChinaProject(2006AA04Z231) supported by the National High-Tech Research and Development Program of China+2 种基金Project(ZJG0709) supported by Key Natural Science Foundation of Heilongjiang Province of ChinaProject(B07018) supported by the Program of Introducing Talents of Discipline to UniversityProject (SKLRS200801A02) supported by Chinese State Key Laboratory of Robotics and System Foundation
文摘In order to investigate wheel slip-sinkage problem, which is important for the design, control and simulation of lunar rovers, experiments were carried out with a wheel-soil interaction test system to measure the sinkage of three types of wheels in dimension with wheel lugs of different heights and numbers under a series of slip ratios (0-0.6). The curves of wheel sinkage versus slip ratio were obtained and it was found that the sinkage with slip ratio of 0.6 is 3-7 times of the static sinkage. Based on the experimental results, the slip-sinkage principle of lunar's rover lugged wheels (including the sinkage caused by longitudinal flow and side flow of soil, and soil digging of wheel lugs) was analyzed, and corresponding calculation equations were derived. All the factors that can cause slip sinkage were considered to improve the conventional wheel-soil interaction model, and a formula of changing the sinkage exponent with the slip ratio was established. Mathematical model for calculating the sinkage of wheel according to vertical load and slip ratio was developed. Calculation results show that this model can predict the slip-sinkage of wheel with high precision, making up the deficiency of Wong-Reece model that mainly reflects longitudinal slip-sinkage.
