This study presents a numerical method for optimizing hull form in calm water with respect to total drag which contains a viscous drag and a wave drag. The ITTC 1957 model-ship correlation line was used to predict fri...This study presents a numerical method for optimizing hull form in calm water with respect to total drag which contains a viscous drag and a wave drag. The ITTC 1957 model-ship correlation line was used to predict frictional drag and the corrected linearized thin-ship theory was employed to estimate the wave drag The evolution strategy （ES） which is a member of the evolutionary algorithms （EAs） family obtains an optimum hull form by considering some design constraints. Standard Wigley hull is considered as an initial hull in optimization procedures for two test cases and new hull forms were achieved at Froude numbers 0.24, 0.316 and 0.408. In one case the ES technique was ran for the initial hull form, where the main dimensions were fixed and the only variables were the hull offsets. In the other case in addition to hull offsets, the raain dimensions were considered as variables that are optimized simultaneously. The numerical results of optimization procedure demonstrate that the optimized hull forms yield a reduction in total drag.展开更多
The numerical simulation of wake and flee-surface flow around ships is a complex topic that involves multiple tasks： the generation of an optimal computational grid and the development of numerical algorithms capable...The numerical simulation of wake and flee-surface flow around ships is a complex topic that involves multiple tasks： the generation of an optimal computational grid and the development of numerical algorithms capable to predict the flow field around a hull. In this paper, a numerical framework is developed aimed at high-resolution CFD simulations of turbulent, free-surface flows around ship hulls. The framework consists in the concatenation of ＂tools＂, partly available in the open-source finite volume library OpenFOAM. A novel, flexible mesh-generation algorithm is presented, capable of producing high-quality computational grids for free-surface ship hydrodynamics. The numerical frame work is used to solve some benchmark problems, providing results that are in excellent agreement with the experimental measures.展开更多
Objective：To compare the value of Glasgow coma scale （GCS） and cerebral state index （CSI）on predicting hospital discharge status of acute braininjured patients.Methods：In 60 brain-injured patients who did not re...Objective：To compare the value of Glasgow coma scale （GCS） and cerebral state index （CSI）on predicting hospital discharge status of acute braininjured patients.Methods：In 60 brain-injured patients who did not receive sedatives,GCS and CSI were measured daily during the first 10 days of hospitalization.The outcome of prognostic cut-off points was calculated by GCS and CSI using receiver operating characteristic （ROC） curve regarding the time of admission and third day of hospitalization.Sensitivity,specificity and other predictive values for both indices were calculated.Results：Of the 60 assessed patients,14 patients had mild,13 patients had moderate and 33 patients had severe injuries.During the course of the study,17 patients （28.3％） deteriorated in their situation and died.The mean GCS and CSI in patients who deceased during hospitalization was significantly lower than those who were discharged from the hospital.GCS＜4.5 and CSI＜64.5 at the time of admission was associated with higher mortality risk in traumatic brain injury patients and GCS was more sensitive than CSI to predict in-hospital death in these patients.For the first day of hospitalization,the area under ROC curve was 0.947 for GCS and 0.732 for CSI.Conclusion：GCS score at ICU admission is a good predictor of in-hospital mortality.GCS＜4.5 and CSI＜64.5 at the time of admission is associated with higher mortality risk in traumatic brain injury patients and GCS is more sensitive than CSI in predicting death in these patients.展开更多
基金marine research institute (MRC) of AUT for some financial support of this project
文摘This study presents a numerical method for optimizing hull form in calm water with respect to total drag which contains a viscous drag and a wave drag. The ITTC 1957 model-ship correlation line was used to predict frictional drag and the corrected linearized thin-ship theory was employed to estimate the wave drag The evolution strategy （ES） which is a member of the evolutionary algorithms （EAs） family obtains an optimum hull form by considering some design constraints. Standard Wigley hull is considered as an initial hull in optimization procedures for two test cases and new hull forms were achieved at Froude numbers 0.24, 0.316 and 0.408. In one case the ES technique was ran for the initial hull form, where the main dimensions were fixed and the only variables were the hull offsets. In the other case in addition to hull offsets, the raain dimensions were considered as variables that are optimized simultaneously. The numerical results of optimization procedure demonstrate that the optimized hull forms yield a reduction in total drag.
文摘The numerical simulation of wake and flee-surface flow around ships is a complex topic that involves multiple tasks： the generation of an optimal computational grid and the development of numerical algorithms capable to predict the flow field around a hull. In this paper, a numerical framework is developed aimed at high-resolution CFD simulations of turbulent, free-surface flows around ship hulls. The framework consists in the concatenation of ＂tools＂, partly available in the open-source finite volume library OpenFOAM. A novel, flexible mesh-generation algorithm is presented, capable of producing high-quality computational grids for free-surface ship hydrodynamics. The numerical frame work is used to solve some benchmark problems, providing results that are in excellent agreement with the experimental measures.
文摘Objective：To compare the value of Glasgow coma scale （GCS） and cerebral state index （CSI）on predicting hospital discharge status of acute braininjured patients.Methods：In 60 brain-injured patients who did not receive sedatives,GCS and CSI were measured daily during the first 10 days of hospitalization.The outcome of prognostic cut-off points was calculated by GCS and CSI using receiver operating characteristic （ROC） curve regarding the time of admission and third day of hospitalization.Sensitivity,specificity and other predictive values for both indices were calculated.Results：Of the 60 assessed patients,14 patients had mild,13 patients had moderate and 33 patients had severe injuries.During the course of the study,17 patients （28.3％） deteriorated in their situation and died.The mean GCS and CSI in patients who deceased during hospitalization was significantly lower than those who were discharged from the hospital.GCS＜4.5 and CSI＜64.5 at the time of admission was associated with higher mortality risk in traumatic brain injury patients and GCS was more sensitive than CSI to predict in-hospital death in these patients.For the first day of hospitalization,the area under ROC curve was 0.947 for GCS and 0.732 for CSI.Conclusion：GCS score at ICU admission is a good predictor of in-hospital mortality.GCS＜4.5 and CSI＜64.5 at the time of admission is associated with higher mortality risk in traumatic brain injury patients and GCS is more sensitive than CSI in predicting death in these patients.
