To enhance machining efficiency,tool change time has to be reduced.Thus,for an automatic tool changer attached to a machining center,the tool change time is to be reduced.Also the automatic tool changer is a main part...To enhance machining efficiency,tool change time has to be reduced.Thus,for an automatic tool changer attached to a machining center,the tool change time is to be reduced.Also the automatic tool changer is a main part of the machining center as a driving source.The static attributes of the automatic tool changer using the commercial code,ANSYS Workbench V12,were tried to interpret.And the optimum design of automatic tool changer arm was proposed by performing the multi-stage optimum design.The shape optimization of the automatic tool changer was proposed and the result was verified to obtain acceptable improvements.It is possible to obtain an optimized model in which the maximum deformation,maximum stress,and mass are reduced by 10.46%,12.89% and 9.26%,respectively,compared with those of the initial model.Also,the results between conventional method by the design of experiments and proposed method by the multi-stage optimum design method were compared.展开更多
Background Atrial fibrillation （AF） is an independent risk factor for ischemic stroke and is associated with increased risk of death. Randomized studies suggest improved quality of life for patients with AF after su...Background Atrial fibrillation （AF） is an independent risk factor for ischemic stroke and is associated with increased risk of death. Randomized studies suggest improved quality of life for patients with AF after successful catheter ablation compared to antiarrhythmic drug therapy. The value of ablation in long-term risk of ischemic stroke, however, has not been assessed. We conducted a meta-analysis to determine whether AF ablation reduces the long-term risk of stroke compared to antiarrhythmic drug therapy in randomized controlled trials. Methods ＆ Results PubMed and the Cochrane Central Register were searched for randomized trials from January 1990 to December 2014 comparing AF catheter ablation to drug therapy. The results are reported as risk differences （RDs） and 95% CI. Thirteen trials were analyzed with 1097 patients treated by catheter ablation and 855 patients received antiarrhythmic drug therapy. Overall, seven patients （0.64%） in the catheter ablation group had ischemic stroke or transient ischemic attacks vs. two patients （0.23%） in the drug therapy group. No difference was shown in the rate of stroke or transient ischemic attack between ablation and drug therapy （RD： 0.003, 95% CI： -0.006 to 0.012, P = 0.470）, and no evidence of heterogeneity was observed （I^2 = 0, P = 0.981）. No potential publication bias was found. There was also no difference in mortality between the two groups （RD： -0.004, 95% CI： -0.014 to 0.006, P = 0.472）. Conclusions This meta-analysis of randomized controlled trials showed similar rates of ischemic stroke or transient ischemic attack and death in AF patients undergoing catheter ablation compared to drug therapy. A larger prospective randomized trial to confirm this finding is warranted.展开更多
The project analyzes the student＇s participation in complementary activities such as Education Tutorial Program, Junior Company and Academic Center. These organizations have the goal to improve, expand and connect kn...The project analyzes the student＇s participation in complementary activities such as Education Tutorial Program, Junior Company and Academic Center. These organizations have the goal to improve, expand and connect knowledge learned during classes with several practical activities. They can provide a huge integration between the students and the professors in order to achieve better results in the pedagogical, structural and organizational parts of an engineering major degree. Therefore, the project goes through the impact of each entity in the student＇s life and the advantages to professional future, focusing the presence of these organizations in the Electrical Engineering Course of Federal University of Rio Grande do Norte.展开更多
We study tile local linear estimator for tile drift coefficient of stochastic differential equations driven by α-stable Levy motions observed at discrete instants. Under regular conditions, we derive the weak consis-...We study tile local linear estimator for tile drift coefficient of stochastic differential equations driven by α-stable Levy motions observed at discrete instants. Under regular conditions, we derive the weak consis- tency and central limit theorem of the estimator. Compared with Nadaraya-Watson estimator, the local linear estimator has a bias reduction whether the kernel function is symmetric or not under different schemes. A silnu- lation study demonstrates that the local linear estimator performs better than Nadaraya-Watson estimator, especially on the boundary.展开更多
基金Work(RTI04-01-03) supported by Grant from Regional Technology Innovation Program of the Ministry of Knowledge Economy (MKE),Korea
文摘To enhance machining efficiency,tool change time has to be reduced.Thus,for an automatic tool changer attached to a machining center,the tool change time is to be reduced.Also the automatic tool changer is a main part of the machining center as a driving source.The static attributes of the automatic tool changer using the commercial code,ANSYS Workbench V12,were tried to interpret.And the optimum design of automatic tool changer arm was proposed by performing the multi-stage optimum design.The shape optimization of the automatic tool changer was proposed and the result was verified to obtain acceptable improvements.It is possible to obtain an optimized model in which the maximum deformation,maximum stress,and mass are reduced by 10.46%,12.89% and 9.26%,respectively,compared with those of the initial model.Also,the results between conventional method by the design of experiments and proposed method by the multi-stage optimum design method were compared.
基金Acknowledgments This study was supported by the National Natural Science Foundation of China （No. 30801213 and No. 81170167）, International Collaboration Projects of Science and Technology Department of Zhejiang Province （No., 2011c14027） and the foundation from Zhejiang Provincial Administration of traditional Chinese Medicine （2011ZQ013）. The corresponding author is sponsored by Zhejiang Provincial Program for the Cultivation of High-level Innovative Health talents.
文摘Background Atrial fibrillation （AF） is an independent risk factor for ischemic stroke and is associated with increased risk of death. Randomized studies suggest improved quality of life for patients with AF after successful catheter ablation compared to antiarrhythmic drug therapy. The value of ablation in long-term risk of ischemic stroke, however, has not been assessed. We conducted a meta-analysis to determine whether AF ablation reduces the long-term risk of stroke compared to antiarrhythmic drug therapy in randomized controlled trials. Methods ＆ Results PubMed and the Cochrane Central Register were searched for randomized trials from January 1990 to December 2014 comparing AF catheter ablation to drug therapy. The results are reported as risk differences （RDs） and 95% CI. Thirteen trials were analyzed with 1097 patients treated by catheter ablation and 855 patients received antiarrhythmic drug therapy. Overall, seven patients （0.64%） in the catheter ablation group had ischemic stroke or transient ischemic attacks vs. two patients （0.23%） in the drug therapy group. No difference was shown in the rate of stroke or transient ischemic attack between ablation and drug therapy （RD： 0.003, 95% CI： -0.006 to 0.012, P = 0.470）, and no evidence of heterogeneity was observed （I^2 = 0, P = 0.981）. No potential publication bias was found. There was also no difference in mortality between the two groups （RD： -0.004, 95% CI： -0.014 to 0.006, P = 0.472）. Conclusions This meta-analysis of randomized controlled trials showed similar rates of ischemic stroke or transient ischemic attack and death in AF patients undergoing catheter ablation compared to drug therapy. A larger prospective randomized trial to confirm this finding is warranted.
文摘The project analyzes the student＇s participation in complementary activities such as Education Tutorial Program, Junior Company and Academic Center. These organizations have the goal to improve, expand and connect knowledge learned during classes with several practical activities. They can provide a huge integration between the students and the professors in order to achieve better results in the pedagogical, structural and organizational parts of an engineering major degree. Therefore, the project goes through the impact of each entity in the student＇s life and the advantages to professional future, focusing the presence of these organizations in the Electrical Engineering Course of Federal University of Rio Grande do Norte.
基金supported by National Natural Science Foundation of China(Grant Nos.11171303 and 11071213)the Specialized Research Fund for the Doctor Program of Higher Education(Grant No.20090101110020)
文摘We study tile local linear estimator for tile drift coefficient of stochastic differential equations driven by α-stable Levy motions observed at discrete instants. Under regular conditions, we derive the weak consis- tency and central limit theorem of the estimator. Compared with Nadaraya-Watson estimator, the local linear estimator has a bias reduction whether the kernel function is symmetric or not under different schemes. A silnu- lation study demonstrates that the local linear estimator performs better than Nadaraya-Watson estimator, especially on the boundary.
