Based on the discussion, the computation process of carrier phase double difference is studied and analyzed with an example of a specific attitude determination test.

The calculated double difference observations Δφ c are derived from the prior known position of the monitor point and reference station,then the deformation vector δ can be derived from the difference between Δφ c and Δφ′ 0 if the deformation value is very small,and its .

This paper analyzes the drawbacks of traditional single-frequency preprocessing method,only by analyzing time series,in complex movement and proposes single-frequency preprocessing method based on double differences.

Vondrak filtering is used to analyze the residual of double-difference,and then a new method for detecting cycle slip together with Vondrak filtering is proposed.

If the intervals are too small in GPS surveying,the double-difference base-line model will be a very bad ill-conditioned and under this circumstances the ambiguity of the least squares estimation is no longer a group of good results.

Futhermore,by comparing the zero-difference kinematic orbit determination with double-difference kinematic,zero-difference reduced-dynamic and double-difference reduced-dynamic orbit determination it is found that with this method not only the accuracy close to that with other three methods can be attained,but also it is simple for computing.

On the analysis of observed connection matrix,this paper proposes an efficient algorithm of generating the minimum sets of GPS double differences together with a demonstrating example.

This paper introduces the lately development of a new kind of method for the design of heat exchanger networks——dual approach temperature method from the aspects of thermodynamics principle design rules and optimal method and so on.