Ill-posed problems are widely existed in signat processing. In this paper, we review popular regularization models such as truncated singular value decomposi- tion regularization, iterative regularization, variational...Ill-posed problems are widely existed in signat processing. In this paper, we review popular regularization models such as truncated singular value decomposi- tion regularization, iterative regularization, variational regularizafion. Meanwhile, we also retrospect popular optimiza- tion approaches and regularization parameter choice meth- ods. In fact, the regularization problem is inherently a multi- objective problem. The traditional methods usually combine the fidelity term and the regularization term into a single- objective with regularization parameters, which are difficult to tune. Therefore, we propose a multi-objective framework for ill-posed problems, which can handle complex features of problem such as non-convexity, discontinuity. In this framework, the fidelity term and regularization term are optimized simultaneously to gain more insights into the ill-posed prob- lems. A case study on signal recovery shows the effectiveness of the multi-objective framework for ill-posed problems.展开更多
Evolutionary algorithms EAs have m any potential applications in power system s operation and control. However,when applying EAs to engineering optimization,there is still a preeminent problem,i. e. the prem ature con...Evolutionary algorithms EAs have m any potential applications in power system s operation and control. However,when applying EAs to engineering optimization,there is still a preeminent problem,i. e. the prem ature convergence problem,which degrades the EAs’perform ance.As such,there has been extensive research from a theoretical point of view in this field to avoid the premature convergence problem and to im prove EAs’performance. This review attem pts to collect,organize and present in a unified way som e of the most representative works in this field.They are categorized into four parts:encoding,self- adaptation,constraints- handling techniques and multi- objective optim ization. An overview on the four technologies is presented herein and it is desired to provide some new ideas for developing successful EAs’applications. This projectis supported by National Natural Science Foundation of China No. 5 0 0 0 70 0 2 and Rencai Yinjin Foundation of HU ST No.AA131F47 .展开更多
Use of hot-stamped high strength steels （HSHSS） not only reduces the vehicle weight, but also improves the crash safety, therefore more and more mentioned steels are used to produce automobile parts. However, there ...Use of hot-stamped high strength steels （HSHSS） not only reduces the vehicle weight, but also improves the crash safety, therefore more and more mentioned steels are used to produce automobile parts. However, there are several problems especially the low ductility and toughness, which have restricted the application of HSHSS in automobile body. Suitable process parameters are very crucial to improve strength and toughness. In order to study the effect of austenization temperature, soaking time and start deformation temperature on strength and toughness of boron steel 22MnB5, an L9 （34） orthogonal experiment which was analyzed by means of comprehensive evaluation was carried out based on Kahn tear method to obtain the value of fracture toughness. The results indicate that the ex- cellent formability, high strength and toughness of boron steel 22MnB5 with 1.6 mm in thickness are obtained when the austenization temperature is in the range of 920- 950 ℃, the soaking time is 1 min and the start deformation temperature is in the range of 650- 700 ℃. The optimal parameters were used for typical hot stamping structural parts tests. Properties of samples such as tear strength, unit initiation energy and ratio of strength to toughness （RST） were improved by 10.91%, 20.32% and 22.17%, respectively. Toughness was increased substantially on the basis of a small decrease of strength.展开更多
文摘Ill-posed problems are widely existed in signat processing. In this paper, we review popular regularization models such as truncated singular value decomposi- tion regularization, iterative regularization, variational regularizafion. Meanwhile, we also retrospect popular optimiza- tion approaches and regularization parameter choice meth- ods. In fact, the regularization problem is inherently a multi- objective problem. The traditional methods usually combine the fidelity term and the regularization term into a single- objective with regularization parameters, which are difficult to tune. Therefore, we propose a multi-objective framework for ill-posed problems, which can handle complex features of problem such as non-convexity, discontinuity. In this framework, the fidelity term and regularization term are optimized simultaneously to gain more insights into the ill-posed prob- lems. A case study on signal recovery shows the effectiveness of the multi-objective framework for ill-posed problems.
文摘Evolutionary algorithms EAs have m any potential applications in power system s operation and control. However,when applying EAs to engineering optimization,there is still a preeminent problem,i. e. the prem ature convergence problem,which degrades the EAs’perform ance.As such,there has been extensive research from a theoretical point of view in this field to avoid the premature convergence problem and to im prove EAs’performance. This review attem pts to collect,organize and present in a unified way som e of the most representative works in this field.They are categorized into four parts:encoding,self- adaptation,constraints- handling techniques and multi- objective optim ization. An overview on the four technologies is presented herein and it is desired to provide some new ideas for developing successful EAs’applications. This projectis supported by National Natural Science Foundation of China No. 5 0 0 0 70 0 2 and Rencai Yinjin Foundation of HU ST No.AA131F47 .
基金Sponsored by National Natural Science Foundation of China(50901011,10932003)National Basic Research Project of China(2010CB832700)+1 种基金"04"Great Project of Ministry of Industrialization and Information of China(2011ZX04001-21)Fundamental Research Funds for Central Universities of China(DUT12LK03)
文摘Use of hot-stamped high strength steels （HSHSS） not only reduces the vehicle weight, but also improves the crash safety, therefore more and more mentioned steels are used to produce automobile parts. However, there are several problems especially the low ductility and toughness, which have restricted the application of HSHSS in automobile body. Suitable process parameters are very crucial to improve strength and toughness. In order to study the effect of austenization temperature, soaking time and start deformation temperature on strength and toughness of boron steel 22MnB5, an L9 （34） orthogonal experiment which was analyzed by means of comprehensive evaluation was carried out based on Kahn tear method to obtain the value of fracture toughness. The results indicate that the ex- cellent formability, high strength and toughness of boron steel 22MnB5 with 1.6 mm in thickness are obtained when the austenization temperature is in the range of 920- 950 ℃, the soaking time is 1 min and the start deformation temperature is in the range of 650- 700 ℃. The optimal parameters were used for typical hot stamping structural parts tests. Properties of samples such as tear strength, unit initiation energy and ratio of strength to toughness （RST） were improved by 10.91%, 20.32% and 22.17%, respectively. Toughness was increased substantially on the basis of a small decrease of strength.
