Accurate hydrodynamic calculations for semi-submersibles are critical to support modern rapid exploration and extraction of ocean resources. In order to speed hydrodynamic calculations, lines modeling structures were ...Accurate hydrodynamic calculations for semi-submersibles are critical to support modern rapid exploration and extraction of ocean resources. In order to speed hydrodynamic calculations, lines modeling structures were separated into structural parts and then fitted to Non-uniform Rational B-spline (NURBS). In this way, the bow and stern section lines were generated. Modeling of the intersections of the parts was then done with the universal modeling tool MSC.Patran. Mesh was gererated on the model in order to obtain points of intersection on the joints, and then these points were fitted to NURBS. Next, the patch representation method was adopted to generate the meshes of wetted surfaces and interior free surfaces. Velocity potentials on the surfaces were calculated separately, on basis of which the irregular frequency effect was dealt with in the calculation of hydrodynamic coefficients. Finally, the motion response of the semi-submersible was calculated, and in order to improve calculations of vertical motion, a damping term was affixed in the vertical direction. The results show that the above methods can generate fine mesh accurately representing the wetted surface of a semi-submersible and thus improve the accuracy of hydrodynamic calculations.展开更多
To increase the efficiency and reliability of the thermodynamics analysis of the hydraulic system, the method based on pseudo-bond graph is introduced. According to the working mechanism of hydraulic components, they ...To increase the efficiency and reliability of the thermodynamics analysis of the hydraulic system, the method based on pseudo-bond graph is introduced. According to the working mechanism of hydraulic components, they can be separated into two categories: capacitive components and resistive components. Then, the thermal-hydraulic pseudo-bond graphs of capacitive C element and resistance R element were developed, based on the conservation of mass and energy. Subsequently, the connection rule for the pseudo-bond graph elements and the method to construct the complete thermal-hydraulic system model were proposed. On the basis of heat transfer analysis of a typical hydraulic circuit containing a piston pump, the lumped parameter mathematical model of the system was given. The good agreement between the simulation results and experimental data demonstrates the validity of the modeling method.展开更多
The structure of the title compound consisting of N,N-1,3-dibenzyl-benzimidazole ion, Cl- anion and hydrate was determined by X-ray diffraction method. It crystallizes in the triclinic system, space group P with a = 9...The structure of the title compound consisting of N,N-1,3-dibenzyl-benzimidazole ion, Cl- anion and hydrate was determined by X-ray diffraction method. It crystallizes in the triclinic system, space group P with a = 9.320(2), b = 9.850(2), c = 11.510(2) ? = 68.75(3), = 80.57(3), = 70.20(3)? C21H19ClN2H2O, Mr = 352.85, V = 925.6(3) 3, Z = 2, Dc = 1.266 g/cm3, F(000) = 372, = 0.217 mm-1, R = 0.0452 and wR = 0.1372. The total reflections were 3462 and 3244 (Rint = 0.0206) were independent, of which 1666 were observed with I > 2s(I). The planes of benzyl group are nearly perpendicular to each other. The water molecules with Cl-anions and C(8) atom are involved in hydrogen bonds and interactions, and - stacking interaction exists obviously between the adjacent phenyl and imidazole rings. The title complex forms a three-dimensional network throughout the structure through these hydrogen bonds and interactions.展开更多
The poly (N-isopropylacrylamide) brush was covalently bonded on an initiator-coated silicon wafer via surface-initiated atom transfer radical polymerization. The polymer brush was (76.2±0.1) nm in thickness (by e...The poly (N-isopropylacrylamide) brush was covalently bonded on an initiator-coated silicon wafer via surface-initiated atom transfer radical polymerization. The polymer brush was (76.2±0.1) nm in thickness (by ellipsometer) with a grafting density of ca. 0.27 chains/nm 2 . The tribological properties of the poly (N-isopropylacrylamide) brush were investigated by means of ball-on-disk tests in a rotational mode under water lubrication for tribological application. The experimental results exhibited a low friction coefficient of ca. 0.03. The excellent lubrication property of the brush was due to its amide groups in the polymer chains. It was supposed that the good lubrication property of the brush was attributed to the cross-linked polymer network formed by the hydrogen bond association of N-H…O==C and the water molecular layer adsorbed by the terminal amide groups in the brush. The poly (N-isopropylacrylamide) solution also exhibits a lubrication property due to physical adsorption of the polymer chains.展开更多
文摘Accurate hydrodynamic calculations for semi-submersibles are critical to support modern rapid exploration and extraction of ocean resources. In order to speed hydrodynamic calculations, lines modeling structures were separated into structural parts and then fitted to Non-uniform Rational B-spline (NURBS). In this way, the bow and stern section lines were generated. Modeling of the intersections of the parts was then done with the universal modeling tool MSC.Patran. Mesh was gererated on the model in order to obtain points of intersection on the joints, and then these points were fitted to NURBS. Next, the patch representation method was adopted to generate the meshes of wetted surfaces and interior free surfaces. Velocity potentials on the surfaces were calculated separately, on basis of which the irregular frequency effect was dealt with in the calculation of hydrodynamic coefficients. Finally, the motion response of the semi-submersible was calculated, and in order to improve calculations of vertical motion, a damping term was affixed in the vertical direction. The results show that the above methods can generate fine mesh accurately representing the wetted surface of a semi-submersible and thus improve the accuracy of hydrodynamic calculations.
基金Project(51175518)supported by the National Natural Science Foundation of China
文摘To increase the efficiency and reliability of the thermodynamics analysis of the hydraulic system, the method based on pseudo-bond graph is introduced. According to the working mechanism of hydraulic components, they can be separated into two categories: capacitive components and resistive components. Then, the thermal-hydraulic pseudo-bond graphs of capacitive C element and resistance R element were developed, based on the conservation of mass and energy. Subsequently, the connection rule for the pseudo-bond graph elements and the method to construct the complete thermal-hydraulic system model were proposed. On the basis of heat transfer analysis of a typical hydraulic circuit containing a piston pump, the lumped parameter mathematical model of the system was given. The good agreement between the simulation results and experimental data demonstrates the validity of the modeling method.
基金The project was supported by the Educational Administration Key Project of Shandong province (No. J01C05) and Natural Science Foundation of Shandong province (No.Y2002B06)
文摘The structure of the title compound consisting of N,N-1,3-dibenzyl-benzimidazole ion, Cl- anion and hydrate was determined by X-ray diffraction method. It crystallizes in the triclinic system, space group P with a = 9.320(2), b = 9.850(2), c = 11.510(2) ? = 68.75(3), = 80.57(3), = 70.20(3)? C21H19ClN2H2O, Mr = 352.85, V = 925.6(3) 3, Z = 2, Dc = 1.266 g/cm3, F(000) = 372, = 0.217 mm-1, R = 0.0452 and wR = 0.1372. The total reflections were 3462 and 3244 (Rint = 0.0206) were independent, of which 1666 were observed with I > 2s(I). The planes of benzyl group are nearly perpendicular to each other. The water molecules with Cl-anions and C(8) atom are involved in hydrogen bonds and interactions, and - stacking interaction exists obviously between the adjacent phenyl and imidazole rings. The title complex forms a three-dimensional network throughout the structure through these hydrogen bonds and interactions.
基金supported by the National Natural Science Foundation of China (Grant Nos. 50805086 and 50730007)the Foundation for Innovative Research Groups of the National Natural Science Foundation of China (Grant No. 51021064)
文摘The poly (N-isopropylacrylamide) brush was covalently bonded on an initiator-coated silicon wafer via surface-initiated atom transfer radical polymerization. The polymer brush was (76.2±0.1) nm in thickness (by ellipsometer) with a grafting density of ca. 0.27 chains/nm 2 . The tribological properties of the poly (N-isopropylacrylamide) brush were investigated by means of ball-on-disk tests in a rotational mode under water lubrication for tribological application. The experimental results exhibited a low friction coefficient of ca. 0.03. The excellent lubrication property of the brush was due to its amide groups in the polymer chains. It was supposed that the good lubrication property of the brush was attributed to the cross-linked polymer network formed by the hydrogen bond association of N-H…O==C and the water molecular layer adsorbed by the terminal amide groups in the brush. The poly (N-isopropylacrylamide) solution also exhibits a lubrication property due to physical adsorption of the polymer chains.
