By applying experimental and numerical simulations, the motion performance of a semi-submersible platform with mooring positoning system under combined actions of wind and waves is studied. The numerical simulation is...By applying experimental and numerical simulations, the motion performance of a semi-submersible platform with mooring positoning system under combined actions of wind and waves is studied. The numerical simulation is conducted by the method of nonlinear time domain coupled analysis, and the mooring forces are calculated by the piecewise extrapolating method. The scale in the model experiment is 1:100, and the mooring system of the model is designed with the method of equivalent water-depth truncation by comparing the numerical and the experimental results, the platform motion and mooring forces subject to wind and waves are investigated. The results indicate that the numerically simulated mooring forces agree well with the experimental results in static equivalent field, but show some difference in dynamic equivalent field; the numerically simulated platform motions coincide well with the experimental results. The maximum motion of the platform under operating conditions is 20.5 m. It means that the horizontal displacement is 2% less than the water depth, which satisfies the operating requirements.展开更多
Large diameter fans with low solidity are widely used in automotive application for engine cooling. Their designs with small chord length help reducing the torque on the electrical motor and providing a good aerodynam...Large diameter fans with low solidity are widely used in automotive application for engine cooling. Their designs with small chord length help reducing the torque on the electrical motor and providing a good aerodynamic compromise between several operating conditions, some of these being at high flow rate. Their global performances are measured according to the ISO standard DP 5801, which allows comparison of results from different facilities. However, some variations in global performances are observed when considering results from two different test rigs. On a fan selected for the purpose of this study, up to 6 % of efficiency is lost on the worst case. As efficiency is more than ever a key factor to select a component, some experimental and numerical investigations were conducted to analyze the fan behavior on each facility. Two sets of measurement and simulation are performed and compared. Geometries considered for the domain of computation include the test rig plenum, the torquemeter, the ground and a large domain for the atmospheric conditions. The exact fan geometry with tip clearance and under-hub ribs is also considered. Numerical results show a good agreement with experiment in both cases when convergence is reached and for low flow rate when computations are switched to unsteady mode. Comparisons show that simulations are able to capture the different fan behaviors depending on the confguration and those efficiency losses previously observed are correctly predicted. These results are further analyzed to perform some post-processing. Blade loading remains identical for both cases but disparities appear in the wake and its interaction with the surrounding. Tiny details that are often neglected during experiment and/or simulation appear to be the cause of slight variations. Position of the torquemeter and shape of the plenum are among the parameters that various and that have cumulative effects. Efficiency being a ration of pressure and torque, variations are rather important. Finally, these results are discussed in terms of rules for conception and a new geometry less sensible to loss of efficiency is proposed.展开更多
The collapsibility of loess, which can be effectively eliminated by the dynamic compaction, does great harm to the safety of constructions. The effect of the dynamic compaction is evaluated through the contrast and an...The collapsibility of loess, which can be effectively eliminated by the dynamic compaction, does great harm to the safety of constructions. The effect of the dynamic compaction is evaluated through the contrast and analysis of the physical and mechanical properties of the collapsible loess before and after dynamic compacting. The compacting effect can be divided into three phases along the depth, and the most effective improved depth is from 3 to 8 m.展开更多
This paper was to validate the effects of airfoil thickness ratio on the characteristics of a family of airfoils. Research was carried out in different ways. First,tests were conducted in the wind tunnel. And numerica...This paper was to validate the effects of airfoil thickness ratio on the characteristics of a family of airfoils. Research was carried out in different ways. First,tests were conducted in the wind tunnel. And numerical simulation was performed on the basis of tests. Results from calculation were consistent with tests,indicating that numerical method could help evaluate characteristics of airfoils. Then the results were confirmed by compared with empirical data. The study also showed that the determining factor of lift is not only the thickness ratio,but the angle of attack,the relative camber and the camber line. The thickness ratio appears to have little effect on lift coefficient at zero angle of attack,since the angle of zero lift is largely determined by the airfoil camber. According to the research,numerical simulation can be used to determine the aerodynamic characteristics of airfoils in different environment such as in the dusty or humid air.展开更多
A new kind of tunnel support was put forward on the basis of the anchor spraysupport principle. The mechanics of the new three-dimensional steel bar shotcrete liningsupport was studied and the structure's internal...A new kind of tunnel support was put forward on the basis of the anchor spraysupport principle. The mechanics of the new three-dimensional steel bar shotcrete liningsupport was studied and the structure's internal forces were analyzed. The model experiment was done relying on the industrial test. The conclusion of numerical calculationsproved that the ANSYS program is reasonable and creditable. It was compared to otherkinds of support that are commonly used in soft rock tunnels. The technique and economiccontrasts of the typical tunnel with support three-dimensional steel bar were completed.展开更多
This article deals with the usage of building bricks as a didactic material for the development of architectural design. The building brick game chosen for analysis was the Arckit, since it is suitable for the archite...This article deals with the usage of building bricks as a didactic material for the development of architectural design. The building brick game chosen for analysis was the Arckit, since it is suitable for the architectural practice. It is estimated that this game can contribute to the design, representation and presentation of projects. In order to investigate in which aspects Arckit presents possibilities of applications, as well as limitations of use, the article approaches the importance of building bricks as a didactic tool and its use in the field of the architectural design process. From a literature review and an empirical experience, this article reports a qualitative research, where the applicability of the Arckit game was checked. Through a critical reflection based on that experience, it was possible to conclude that whereas its limitations to urban form and linked to the formal vocabulary that composes the grammar of these bricks, the Arckit building bricks represent in architecture a playful and experimental way to think and design, fomenting the creativity and the spatial perception, resulting in a particular experience that can make architecture better connected with dreams and joy.展开更多
The inclining experiment is the only regulatory tool to assess ship stability. This experiment is a time consuming process for both real-life tests and ship model experiments. The difficulty is mainly due to a bias in...The inclining experiment is the only regulatory tool to assess ship stability. This experiment is a time consuming process for both real-life tests and ship model experiments. The difficulty is mainly due to a bias in the measurement of heel angle. Nowadays, digital inclinometers are available, but they are expensive. In this study, the use of a smartphone application is presented for ship inclination and rolling-period tests. The idea consists of using accelerometer and gyroscope sensors built into the current smartphones for the measurements. Therefore, some experiments are carried out on an example trawler model to exhibit the uses and advantages of this method. The obtained results are in good agreement with those provided from the pendulum method and natural roll-period test. This application is new, easy, and more accurately assesses metacentric height during the inclining and rolling-period tests.展开更多
文摘By applying experimental and numerical simulations, the motion performance of a semi-submersible platform with mooring positoning system under combined actions of wind and waves is studied. The numerical simulation is conducted by the method of nonlinear time domain coupled analysis, and the mooring forces are calculated by the piecewise extrapolating method. The scale in the model experiment is 1:100, and the mooring system of the model is designed with the method of equivalent water-depth truncation by comparing the numerical and the experimental results, the platform motion and mooring forces subject to wind and waves are investigated. The results indicate that the numerically simulated mooring forces agree well with the experimental results in static equivalent field, but show some difference in dynamic equivalent field; the numerically simulated platform motions coincide well with the experimental results. The maximum motion of the platform under operating conditions is 20.5 m. It means that the horizontal displacement is 2% less than the water depth, which satisfies the operating requirements.
文摘Large diameter fans with low solidity are widely used in automotive application for engine cooling. Their designs with small chord length help reducing the torque on the electrical motor and providing a good aerodynamic compromise between several operating conditions, some of these being at high flow rate. Their global performances are measured according to the ISO standard DP 5801, which allows comparison of results from different facilities. However, some variations in global performances are observed when considering results from two different test rigs. On a fan selected for the purpose of this study, up to 6 % of efficiency is lost on the worst case. As efficiency is more than ever a key factor to select a component, some experimental and numerical investigations were conducted to analyze the fan behavior on each facility. Two sets of measurement and simulation are performed and compared. Geometries considered for the domain of computation include the test rig plenum, the torquemeter, the ground and a large domain for the atmospheric conditions. The exact fan geometry with tip clearance and under-hub ribs is also considered. Numerical results show a good agreement with experiment in both cases when convergence is reached and for low flow rate when computations are switched to unsteady mode. Comparisons show that simulations are able to capture the different fan behaviors depending on the confguration and those efficiency losses previously observed are correctly predicted. These results are further analyzed to perform some post-processing. Blade loading remains identical for both cases but disparities appear in the wake and its interaction with the surrounding. Tiny details that are often neglected during experiment and/or simulation appear to be the cause of slight variations. Position of the torquemeter and shape of the plenum are among the parameters that various and that have cumulative effects. Efficiency being a ration of pressure and torque, variations are rather important. Finally, these results are discussed in terms of rules for conception and a new geometry less sensible to loss of efficiency is proposed.
基金Acknowledgement The authors of this paper thank the financial support from National Natural Science Foundation of China through project No.50478096.
文摘The collapsibility of loess, which can be effectively eliminated by the dynamic compaction, does great harm to the safety of constructions. The effect of the dynamic compaction is evaluated through the contrast and analysis of the physical and mechanical properties of the collapsible loess before and after dynamic compacting. The compacting effect can be divided into three phases along the depth, and the most effective improved depth is from 3 to 8 m.
文摘This paper was to validate the effects of airfoil thickness ratio on the characteristics of a family of airfoils. Research was carried out in different ways. First,tests were conducted in the wind tunnel. And numerical simulation was performed on the basis of tests. Results from calculation were consistent with tests,indicating that numerical method could help evaluate characteristics of airfoils. Then the results were confirmed by compared with empirical data. The study also showed that the determining factor of lift is not only the thickness ratio,but the angle of attack,the relative camber and the camber line. The thickness ratio appears to have little effect on lift coefficient at zero angle of attack,since the angle of zero lift is largely determined by the airfoil camber. According to the research,numerical simulation can be used to determine the aerodynamic characteristics of airfoils in different environment such as in the dusty or humid air.
文摘A new kind of tunnel support was put forward on the basis of the anchor spraysupport principle. The mechanics of the new three-dimensional steel bar shotcrete liningsupport was studied and the structure's internal forces were analyzed. The model experiment was done relying on the industrial test. The conclusion of numerical calculationsproved that the ANSYS program is reasonable and creditable. It was compared to otherkinds of support that are commonly used in soft rock tunnels. The technique and economiccontrasts of the typical tunnel with support three-dimensional steel bar were completed.
文摘This article deals with the usage of building bricks as a didactic material for the development of architectural design. The building brick game chosen for analysis was the Arckit, since it is suitable for the architectural practice. It is estimated that this game can contribute to the design, representation and presentation of projects. In order to investigate in which aspects Arckit presents possibilities of applications, as well as limitations of use, the article approaches the importance of building bricks as a didactic tool and its use in the field of the architectural design process. From a literature review and an empirical experience, this article reports a qualitative research, where the applicability of the Arckit game was checked. Through a critical reflection based on that experience, it was possible to conclude that whereas its limitations to urban form and linked to the formal vocabulary that composes the grammar of these bricks, the Arckit building bricks represent in architecture a playful and experimental way to think and design, fomenting the creativity and the spatial perception, resulting in a particular experience that can make architecture better connected with dreams and joy.
文摘The inclining experiment is the only regulatory tool to assess ship stability. This experiment is a time consuming process for both real-life tests and ship model experiments. The difficulty is mainly due to a bias in the measurement of heel angle. Nowadays, digital inclinometers are available, but they are expensive. In this study, the use of a smartphone application is presented for ship inclination and rolling-period tests. The idea consists of using accelerometer and gyroscope sensors built into the current smartphones for the measurements. Therefore, some experiments are carried out on an example trawler model to exhibit the uses and advantages of this method. The obtained results are in good agreement with those provided from the pendulum method and natural roll-period test. This application is new, easy, and more accurately assesses metacentric height during the inclining and rolling-period tests.
