This paper provided an overview on the adverse effects of contaminated sediment and on the in situ capping technology,a simply operated and low cost technology for the remediation of contaminated sediment.

Considering the conventional algorithms for calculating the coverage area of radar net, such as grid-ding based on digital map and edge scanning method, have their inherent limitations, this article presents a new algorithm with point-to-point decision, which is applicable to calculating the coverage area of radardetection in arbitrary form net.

The paper recommends to increase the retirement ages gradually and to enlarge coverage by old-age social insurance syste.

With the economic development and our social progress,our party and country have been putting emphasis on extending the coverage of social security as well as gradually realizing social justice.

It is important to extend the coverage of the basic social security insurance in the development of socialist market economy and the improvement of people s life quality.