A constrained least squares method for estimating the effects of an unknown monotonically intervening factor

1989 ◽  
Vol 8 (4) ◽  
pp. 369-379 ◽  
Author(s):  
Sten Thore
Keyword(s):  
Least Squares ◽  
Least Squares Method ◽  
Constrained Least Squares

Constrained Least-Squares Method for Computing Equivalent Static Wind Loads of Large-Span Roofs

2014 ◽  
Vol 17 (10) ◽  
pp. 1497-1515 ◽  
Author(s):  
Xuanyi Zhou ◽  
Ming Gu ◽  
Gang Li
Keyword(s):  
Least Squares ◽  
Large Scale ◽  
Least Squares Method ◽  
Weighting Factor ◽  
Wind Loads ◽  
Specific Response ◽  
Computational Accuracy ◽  
Constrained Least Squares ◽  
Large Span ◽  
Equivalent Static Wind Loads

Equivalent static wind loads (ESWL) are widely used by structural designers to determine a specific response of large-scale structures. However, structural designers usually pay attention to more responses. Thus, this study proposes a constrained least-squares method to compute the ESWL distribution that can simultaneously target multi-responses. The loading distribution is regarded as a linear combination of basic load distributions. Two forms of basic load distribution are presented herein. The magnitude range of ESWLs is limited by controlling the bounds of the participation factor, which can be regarded as a constrained linear least-squares problem. Furthermore, since only a few structural responses are usually emphasized by structural designers, weighting factor is imported to improve the accuracy of these focused responses. To verify its computational accuracy, the method is applied to a real large-span roof structure. The results of calculations show that a reasonable magnitude of ESWL distribution can be achieved. There seems to always be a balance between the number of targeted responses and computational accuracy.

Constrained Least Squares Method Used in Nuclear Accident Source Term Inversion

2017 ◽  
Author(s):  
Wang Xuan ◽  
Du Fenglei ◽  
Huang Xiaodong
Keyword(s):  
Least Squares ◽  
Diffusion Model ◽  
Source Term ◽  
Least Squares Method ◽  
Nuclear Accident ◽  
Constrained Least Squares ◽  
Atmospheric Diffusion ◽  
Inversion Model ◽  
Site Monitoring ◽  
Simulation Results

Through experience feedback of the Chernobyl and Fukushima nuclear accidents, source term determination including release rates and release curves, becomes a key issue in nuclear accident impact assessment. When faced with monitoring device failure, use of off-site monitoring data and atmospheric dispersion model simulation results to inverse the source term has been proven an effective means in many case studies. In this paper, we have developed a powerful source term inverse system based on constrained least squares algorithm approach and Gaussian atmospheric diffusion model, and we carried out 15 SF6 field trace experiments at a coastal nuclear power plant site in China from August 22, 2007 to August 31,2007, to validate the source term inversion model. From the 15 simulation results, the 5th,8th and 9th inverse results are the best, and the relative error of inverse source term and true source term is between 10.12% and 16.42%, this is mainly because these three experiments are the most successful, and effective sample points of three experiments are above 25, its distribution is also uniform. It is shown that accuracy, number and distribution of the on-site monitoring will directly affect the inversion source term results. In general, results of source term inversion model are close to the field experiment, within the same magnitude, which shows that constrained least squares algorithm method and Gaussian atmospheric diffusion model can be applied in nuclear accident source term determination. Results of this study show that constrained least squares method is simple and highly efficient and has a high application value.

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