Suchergebnisse

International audience ; Grain production is of great importance to any country, especially to China. It is very important for local and central governments to get accurate main crops acreage information in time. One noticeable problem is that the estimated accuracy for crops acreage in a certain year is not high, so that Remote Sensing Applications Centre (RSAC) has to use investigated data of crops acreage of two consecutive years to estimate the change rate of crops acreage.Aiming at the issue, the theory of double sampling based on operational crops acreage investigation was brought forward by RSAC. The paper has given detailed account of the theory and a typical case. In the double sampling method, the first sampling is to estimate the proportion of small features spatially distributing in crops fields in order to purify the samples acting as basis units for calculation in the second sampling. The second sampling is called a kind of stratified sampling which is used to estimate the crops acreage. The test is by adopting the theory of double sampling with 3S to evaluate the planting acreage of cotton and late-rice, acting as representatives of main crops in China, related to operative task and project research. The experiment result described with statistic methods shows that the theory of double sampling applied to main crops acreage monitoring can efficiently improve the estimated accuracy of crops acreage.

International audience ; Monitoring crops with Remote Sensing (RS) at the national scale is usually an operational work acted as a normal business for the government needs to the crop field conditions. The crop information is main content of agricultural condition. It mainly includes crop growth, crop areas and crop yields, which can be named 3 factors for crop monitoring with RS. Diversification is the general feature of crop monitoring with RS, which reflects in 3 parts of labor objects, labor materials and labor process. Monitoring the 3 factors with RS has similar process summarized as 3 periods which are data acquisition and transmission, model development and application, producing products. Monitoring crops with RS at the national scale needs to found an organizational and technical system, using the System Theory according to the 3 factors, the 3 parts and the 3 periods, mentioned above. The operational work of monitoring the 3 factors have a common goal, which is that the monitoring result is more accurate, the monitoring process is faster, more economic and more convenient. In China, Remote Sensing Application Centre (RSAC) has been working on monitoring the main crops as an operational task and a research project based on its system for several years. The monitoring methods to the 3 factors are presented in this paper along with the cases coming from the monitoring products produced by RSAC in 2014.

Teacher leadership has been found to be positively associated with student achievement, and the dimensions of teacher leadership positively associated with teacher leadership have been identified. However, mechanisms to improve teacher leadership and the effects of these mechanisms are rarely studied. In this article, we report the efforts to develop teacher leadership in a multi-year, large-scale project titled, "High- Impact Leadership for School Renewal", and the effects of these efforts. Repeated measure analysis was conducted to assess the project's effect on teacher leadership using validated and published instruments. The results indicated that the project had large effects on enhancing teacher leadership, with Cohen's d effect size ranging from 0.85 to 1.16 for scales of Orientation to School Renewal and from 0.87 to 1.13 for scales of Learning-Centered School Leadership. Implications for school renewal are discussed.