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Grassland ecosystem is the most important terrestrial ecosystem. Only by accurately estimating grassland yield and productivity can we effectively protect the ecosystem. This thesis is based on 323 monitoring data and MODIS-NDVI and MODIS-EVI vegetation index corresponding to the same period from 2012 to 2016, Based on the establishment of grassland yield estimation model, the grassland yield of Sunan County was estimated. The results show that: (1) After validating the model equations corresponding to the five production areas through the reserved precision verifying points, the model accuracy is higher than 90%, and it is feasible to estimate production by remote sensing.(2) From 2012 to 2016, the average yield of grass in Sunan County was 89.92 million tons, and the average yield per unit area was 524.12 kg/h m2.(3) Grass yield in Sunan County decreased from southeast to northwest during 2012-2016, and the overall grass yield showed a slow downward trend.(4) The annual grass yield in the study area is directly proportional to the annual precipitation and average annual temperature, and the annual precipitation has a greater impact on the annual grass yield.

With increasing reliability and long service life, space vehicle electrical system is often difficult to obtain sufficient information about the reliability model under traditional statistic method. Considering the requirement of life evaluation, this paper introduces the accelerated testing concepts and theories which are suitable for space vehicle electrical system. Taking a certain power supply product as an example, the ALT model is chosen and the accelerated life testing spectrum is designed with constrained conditions in practice. At last, the possible directions for further research in reliability assessment are summarized.

One redundant wireless bridged network is proposed to transport the measuring data and control command for the remote launch system. For the importance, the high reliability is required in the process of system design. So the redundant technology and voting approach are used to improve the reliability of system. The master-slave double wireless links are built up, when the master link broken down, the data can be transported by slave link immediately. Based on the high performance wireless bridge, the network has >200Mbps bandwidth, 5∼50km communication distance and high reliability, which can fulfils the requirements of remote launch system.

In this paper, the artificial potential field method was applied to the formation control and real-time path planning in unknown environment for mobile robots; in the same time, we find a method for mutual cooperation between the robots in the process of obstacle avoidance, and the emergency treatment to special circumstances, Which can deal with the local minimum problem in artificial field approach. The simulation experiments show that the method is effective.