BACKGROUND Transanal minimally invasive surgery(TAMIS)is a good choice for resection of rectal neoplasms.Endoscopic mucosal resection(EMR)is also widely used in the treatment of benign rectal tumors such as rectal pol...BACKGROUND Transanal minimally invasive surgery(TAMIS)is a good choice for resection of rectal neoplasms.Endoscopic mucosal resection(EMR)is also widely used in the treatment of benign rectal tumors such as rectal polyps and rectal adenomas.However,no studies have compared the outcome of TAMIS and EMR.AIM To compare the short-term outcomes after TAMIS and EMR for rectal carcinoid and benign tumors(including rectal polyps and adenomas).METHODS From January 2014 to January 2019,44 patients who received TAMIS and 53 patients who received EMR at The Fifth People's Hospital of Shanghai were selected.Primary outcomes(surgical-related)were operating time,blood loss,length of postoperative hospital stay,rate of resection margin involvement and lesion fragmentation rate.The secondary outcomes were complications such as hemorrhage,urinary retention,postoperative infection and reoperation.RESULTS No significant differences were observed in terms of blood loss(12.48±8.00 mL for TAMIS vs 11.45±7.82 mL for EMR,P=0.527)and length of postoperative hospital stay(3.50±1.87 d for TAMIS vs 2.72±1.98 d for EMR,P=0.065)between the two groups.Operating time was significantly shorter for EMR compared with TAMIS(21.19±9.49 min vs 49.95±15.28 min,P=0.001).The lesion fragmentation rate in the EMR group was 22.6%(12/53)and was significantly higher than that(0%,0/44)in the TAMIS group(P=0.001).TAMIS was associated with a higher urinary retention rate(13.6%,6/44 vs 1.9%,1/53 P=0.026)and lower hemorrhage rate(0%,0/44 vs 18.9%,10/53 P=0.002).A significantly higher reoperation rate was observed in the EMR group(9.4%,5/53 vs 0%,0/44 P=0.036).展开更多
In this paper, we propose a retrospective filter trust region algorithm for unconstrained optimization, which is based on the framework of the retrospective trust region method and associated with the technique of the...In this paper, we propose a retrospective filter trust region algorithm for unconstrained optimization, which is based on the framework of the retrospective trust region method and associated with the technique of the multi-dimensional filter. The new algorithm gives a good estimation of trust region radius, relaxes the condition of accepting a trial step for the usual trust region methods. Under reasonable assumptions, we analyze the global convergence of the new method and report the preliminary results of numerical tests. We compare the results with those of the basic trust region algorithm, the filter trust region algorithm and the retrospective trust region algorithm, which shows the effectiveness of the new algorithm.展开更多
The truncated singular value decomposition has been widely used in many areas of science including engineering,and statistics,etc.In this paper,the original truncated complex singular value decomposition problem is fo...The truncated singular value decomposition has been widely used in many areas of science including engineering,and statistics,etc.In this paper,the original truncated complex singular value decomposition problem is formulated as a Riemannian optimiza-tion problem on a product of two complex Stiefel manifolds,a practical algorithm based on the generic Riemannian trust-region method of Absil et al.is presented to solve the underlying problem,which enjoys the global convergence and local superlinear conver-gence rate.Numerical experiments are provided to illustrate the efficiency of the proposed method.Comparisons with some classical Riemannian gradient-type methods,the existing Riemannian version of limited-memory BFGS algorithms in the MATLAB toolbox Manopt and the Riemannian manifold optimization library ROPTLIB,and some latest infeasible methods for solving manifold optimization problems,are also provided to show the merits of the proposed approach.展开更多
Trust-region methods are popular for nonlinear optimization problems. How to determine the predicted reduction of the trust-region subproblem is a key issue for trust-region methods. Powell gave an estimation of the l...Trust-region methods are popular for nonlinear optimization problems. How to determine the predicted reduction of the trust-region subproblem is a key issue for trust-region methods. Powell gave an estimation of the lower bound of the trust-region subproblem by considering the negative gradient direction. In this article, we give an alternate way to estimate the same lower bound of the trust-region subproblem.展开更多
We propose a trust-region type method for a class of nonsmooth nonconvex optimization problems where the objective function is a summation of a(probably nonconvex)smooth function and a(probably nonsmooth)convex functi...We propose a trust-region type method for a class of nonsmooth nonconvex optimization problems where the objective function is a summation of a(probably nonconvex)smooth function and a(probably nonsmooth)convex function.The model function of our trust-region subproblem is always quadratic and the linear term of the model is generated using abstract descent directions.Therefore,the trust-region subproblems can be easily constructed as well as efficiently solved by cheap and standard methods.When the accuracy of the model function at the solution of the subproblem is not sufficient,we add a safeguard on the stepsizes for improving the accuracy.For a class of functions that can be“truncated”,an additional truncation step is defined and a stepsize modification strategy is designed.The overall scheme converges globally and we establish fast local convergence under suitable assumptions.In particular,using a connection with a smooth Riemannian trust-region method,we prove local quadratic convergence for partly smooth functions under a strict complementary condition.Preliminary numerical results on a family of Ei-optimization problems are reported and demonstrate the eficiency of our approach.展开更多
基金the Science and Technology Commission of Shanghai Municipally,No.17411967600.
文摘BACKGROUND Transanal minimally invasive surgery(TAMIS)is a good choice for resection of rectal neoplasms.Endoscopic mucosal resection(EMR)is also widely used in the treatment of benign rectal tumors such as rectal polyps and rectal adenomas.However,no studies have compared the outcome of TAMIS and EMR.AIM To compare the short-term outcomes after TAMIS and EMR for rectal carcinoid and benign tumors(including rectal polyps and adenomas).METHODS From January 2014 to January 2019,44 patients who received TAMIS and 53 patients who received EMR at The Fifth People's Hospital of Shanghai were selected.Primary outcomes(surgical-related)were operating time,blood loss,length of postoperative hospital stay,rate of resection margin involvement and lesion fragmentation rate.The secondary outcomes were complications such as hemorrhage,urinary retention,postoperative infection and reoperation.RESULTS No significant differences were observed in terms of blood loss(12.48±8.00 mL for TAMIS vs 11.45±7.82 mL for EMR,P=0.527)and length of postoperative hospital stay(3.50±1.87 d for TAMIS vs 2.72±1.98 d for EMR,P=0.065)between the two groups.Operating time was significantly shorter for EMR compared with TAMIS(21.19±9.49 min vs 49.95±15.28 min,P=0.001).The lesion fragmentation rate in the EMR group was 22.6%(12/53)and was significantly higher than that(0%,0/44)in the TAMIS group(P=0.001).TAMIS was associated with a higher urinary retention rate(13.6%,6/44 vs 1.9%,1/53 P=0.026)and lower hemorrhage rate(0%,0/44 vs 18.9%,10/53 P=0.002).A significantly higher reoperation rate was observed in the EMR group(9.4%,5/53 vs 0%,0/44 P=0.036).
文摘In this paper, we propose a retrospective filter trust region algorithm for unconstrained optimization, which is based on the framework of the retrospective trust region method and associated with the technique of the multi-dimensional filter. The new algorithm gives a good estimation of trust region radius, relaxes the condition of accepting a trial step for the usual trust region methods. Under reasonable assumptions, we analyze the global convergence of the new method and report the preliminary results of numerical tests. We compare the results with those of the basic trust region algorithm, the filter trust region algorithm and the retrospective trust region algorithm, which shows the effectiveness of the new algorithm.
基金supported by the National Natural Science Foundation of China(Grant Nos.12261026,11961012,12201149)by the Natural Science Foundation of Guangxi Province(Grant Nos.2016GXNSFAA380074,2023GXNSFAA026067)+4 种基金by the Innovation Project of GUET Graduate Education(Grant No.2022YXW01)by the GUET Graduate Innovation Project(Grant No.2022YCXS142)by the Guangxi Key Laboratory of Automatic Detecting Technology and Instruments(Grant Nos.YQ23103,YQ21103,YQ22106)by the Special Fund for Science and Technological Bases and Talents of Guangxi(Grant No.2021AC06001)by the Guizhou Science and Technology Program of Projects(Grant No.ZK2021G339)。
文摘The truncated singular value decomposition has been widely used in many areas of science including engineering,and statistics,etc.In this paper,the original truncated complex singular value decomposition problem is formulated as a Riemannian optimiza-tion problem on a product of two complex Stiefel manifolds,a practical algorithm based on the generic Riemannian trust-region method of Absil et al.is presented to solve the underlying problem,which enjoys the global convergence and local superlinear conver-gence rate.Numerical experiments are provided to illustrate the efficiency of the proposed method.Comparisons with some classical Riemannian gradient-type methods,the existing Riemannian version of limited-memory BFGS algorithms in the MATLAB toolbox Manopt and the Riemannian manifold optimization library ROPTLIB,and some latest infeasible methods for solving manifold optimization problems,are also provided to show the merits of the proposed approach.
文摘Trust-region methods are popular for nonlinear optimization problems. How to determine the predicted reduction of the trust-region subproblem is a key issue for trust-region methods. Powell gave an estimation of the lower bound of the trust-region subproblem by considering the negative gradient direction. In this article, we give an alternate way to estimate the same lower bound of the trust-region subproblem.
基金partly supported by the Fundamental Research Fund-Shenzhen Research Institute for Big Data(SRIBD)Startup Fund JCYJ-AM20190601partly supported by the NSFC grant 11831002the Beijing Academy of Artificial Intelligence.
文摘We propose a trust-region type method for a class of nonsmooth nonconvex optimization problems where the objective function is a summation of a(probably nonconvex)smooth function and a(probably nonsmooth)convex function.The model function of our trust-region subproblem is always quadratic and the linear term of the model is generated using abstract descent directions.Therefore,the trust-region subproblems can be easily constructed as well as efficiently solved by cheap and standard methods.When the accuracy of the model function at the solution of the subproblem is not sufficient,we add a safeguard on the stepsizes for improving the accuracy.For a class of functions that can be“truncated”,an additional truncation step is defined and a stepsize modification strategy is designed.The overall scheme converges globally and we establish fast local convergence under suitable assumptions.In particular,using a connection with a smooth Riemannian trust-region method,we prove local quadratic convergence for partly smooth functions under a strict complementary condition.Preliminary numerical results on a family of Ei-optimization problems are reported and demonstrate the eficiency of our approach.
