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 surface of nanocrystals plays a dominant role in many of their physical and chemical properties.However,controllability and tunability of nanocrystal surfaces remain unsolved.Herein,we report that the surface chem...The surface of nanocrystals plays a dominant role in many of their physical and chemical properties.However,controllability and tunability of nanocrystal surfaces remain unsolved.Herein,we report that the surface chemistry of nanocrystals,such as near-infrared Ag_(2)Se quantum dots(QDs),is sizedependent and composition-tunable.The Ag_(2)Se QDs tend to form a stable metal complex on the surface to minimize the surface energy,and therefore the surface chemistry can be varied with particle size.Meanwhile,changes in surface inorganic composition lead to reorganization of the surface ligands,and the surface chemistry also varies with composition.Therefore,the surface chemistry of Ag_(2)Se QDs,responsible for the photoluminescence(PL)quantum yield and photostability,can be tuned by changing their size or composition.Accordingly,we demonstrate that the PL intensity of the Ag_(2)Se QDs can be tuned reversely by adjusting the degree of surface Ag^(+) enrichment via light irradiation or the addition of AgNO_(3).This work provides insight into the control of QD surface for desired PL properties.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.
基金supported by the National Natural Science Foundation of China(91859123)the National Key R&D Program of China(2019YFA0210103)。
文摘The surface of nanocrystals plays a dominant role in many of their physical and chemical properties.However,controllability and tunability of nanocrystal surfaces remain unsolved.Herein,we report that the surface chemistry of nanocrystals,such as near-infrared Ag_(2)Se quantum dots(QDs),is sizedependent and composition-tunable.The Ag_(2)Se QDs tend to form a stable metal complex on the surface to minimize the surface energy,and therefore the surface chemistry can be varied with particle size.Meanwhile,changes in surface inorganic composition lead to reorganization of the surface ligands,and the surface chemistry also varies with composition.Therefore,the surface chemistry of Ag_(2)Se QDs,responsible for the photoluminescence(PL)quantum yield and photostability,can be tuned by changing their size or composition.Accordingly,we demonstrate that the PL intensity of the Ag_(2)Se QDs can be tuned reversely by adjusting the degree of surface Ag^(+) enrichment via light irradiation or the addition of AgNO_(3).This work provides insight into the control of QD surface for desired PL properties.
