Monotonic lateral load model tests were carried out on steel skirted suction caissons embedded in the saturated medium sand to study the bearing capacity. A three-dimensional continuum finite element model was develop...Monotonic lateral load model tests were carried out on steel skirted suction caissons embedded in the saturated medium sand to study the bearing capacity. A three-dimensional continuum finite element model was developed with Z_SOIL software. The numerical model was calibrated against experimental results. Soil deformation and earth pressures on skirted caissons were investigated by using the finite element model to extend the model tests. It shows that the ＂skirted＂ structure can significantly increase the lateral capacity and limit the deflection, especially suitable for offshore wind turbines, compared with regular suction caissons without the ＂skirted＂ at the same load level. In addition, appropriate determination of rotation centers plays a crucial role in calculating the lateral capacity by using the analytical method. It was also found that the rotation center is related to dimensions of skirted suction caissons and loading process, i.e. the rotation center moves upwards with the increase of the ＂skirted＂ width and length; moreover, the rotation center moves downwards with the increase of loading and keeps constant when all the sand along the caisson＇s wall yields. It is so complex that we cannot simply determine its position like the regular suction caisson commonly with a specified position to the length ratio of the caisson.展开更多
Based on the rigid-plastic theory, the finite element method (FEM) equation which incorporates the influence of impact load and volume force is presented. The hammer forging theory for simulation is also given. On the...Based on the rigid-plastic theory, the finite element method (FEM) equation which incorporates the influence of impact load and volume force is presented. The hammer forging theory for simulation is also given. On the basis of technological analyses, the piston skirt forging processes of LD11 aluminium alloy are simulated under both mechanical pressure forging and hammer forging conditions. By comparison with the metal flow, fibre flow lines, distributions of strain and temperature of the two forging methods, practical forging was carried out and the product quality was controlled. The deformation pattern of the piston skirt forging process was determined by comparing the simulation results with the practical forging results.展开更多
The processes of scallop meats can produce a large amount of by-products like scallop skirts,which are rich in nutrients. This work aimed to obtain the information about antioxidant peptides derived from scallop skirt...The processes of scallop meats can produce a large amount of by-products like scallop skirts,which are rich in nutrients. This work aimed to obtain the information about antioxidant peptides derived from scallop skirts of Mimachlamys nobilis. The hydro-lysates obtained by trypsin exhibited the highest antioxidant activity( 75.6%,79.5% and 76.7% using DPPH,hydroxyl and superoxide anion radical scavenging activity assays,respectively). The antioxidant peptides( MNAP) were separated and purified using UF membranes,GFC processes and RP-HPLC,and the antioxidant activity of MNAP was identified to be 85.7% using DPPH radical scavenging activity assay. The peptides( MNAP) were composed of two peptides with their molecular weights2 855.6 Da and 3 007.2 Da using MALDI-TOF-MS,respectively. The results suggested that the scallop skirts of Mimachlamys nobilis could be explored as a source of antioxidant peptides.展开更多
The influence of oil film inertia on piston skirt lubrication in a high speedengine is investigated by an iteration method that alternately solves the Navier-Stocks equationsand the Reynolds equa-tion by finite elemen...The influence of oil film inertia on piston skirt lubrication in a high speedengine is investigated by an iteration method that alternately solves the Navier-Stocks equationsand the Reynolds equa-tion by finite element method and difference method. The Reynolds lubricationequation including oil film inertia is developed, in which the inertia coefficient is introduced toinvestigate the effect of oil film inertia. The iteration procedure and finite formulation ofsolving the new Reynolds lubrication equation are given to analyze the effect of oil film on pistonskirt in this kind of engine. The calculation results show that the oil film inertia has someeffects on the friction force, pressure force and load capacity of oil film and its effect isobvious for the last. The Reynolds lubrication equation proposed can be also used to analyze thelubrication performance of the piston skirt in low or medium speed engine and some other lubricationproblems generally excluding oil film inertia with the inertia coefficient being set at zero.展开更多
By an iteration method, the influence of oil film inertia on piston skirt lubrication in a high speed engine is investigated. By alternately solving the Navier-Stocks equations and the Reynolds equation, the new itera...By an iteration method, the influence of oil film inertia on piston skirt lubrication in a high speed engine is investigated. By alternately solving the Navier-Stocks equations and the Reynolds equation, the new iteration method can trace the variations of velocity field and pressure field with time. Based on this, the mixed-lubrication model suitable for the piston skirt of high engines is proposed. By introducing the inertia coefficient, the new lubrication model includes the inertia term in oil film. The model can be also used to solve for the lubrication performances of a piston skirt in low or medium speed engines and for lubrication problem in general excluding the inertia term of oil film , when the inertia coefficient is put equal to zero. The calculation results show that the influence of oil film inertia on the friction force increases with the ratio of the piston skirt's length to its diameter, the inertia coefficient and the eccentricities of the lower and the upper piston skirt, with other conditions kept constant, while the influence of it on the load capacity of oil film is small.展开更多
A mixed lubrication model was established for piston skirt lubrication. The mathematical model developed in this paper incorporates governing equations of motion with average Reynolds equation. This model considers th...A mixed lubrication model was established for piston skirt lubrication. The mathematical model developed in this paper incorporates governing equations of motion with average Reynolds equation. This model considers the surfaceroughness and profile. The corresponding computer program can be used to calculate oscillatory motion of piston during the entire trajectory, which has the excellent convergence.In addition, a set of equipment, which adopt the laser induced fluorescent method, was developed to measure the oil film thickness between the piston and the bore.展开更多
In this work, a novel parameter called the surface skirt (Ss) is introduced. The electron beam scattering by gaseous environment is the fundamental parameter limiting the performance of the Gaseous Scanning Electron M...In this work, a novel parameter called the surface skirt (Ss) is introduced. The electron beam scattering by gaseous environment is the fundamental parameter limiting the performance of the Gaseous Scanning Electron Microscopy (GSEM). The result is the enlargement of the primary beam characterized by the radius skirt Rs. The scattering phenomena require a much closer re-examination. In fact, depending on the localization of EDX detector and the particles shape to analyze, the collected signal after the beam skirt will be different and Rs also will be different. So, except for homogeneous materials, Rs can not describe the scattering behavior. In this study, the surface skirt Ss instead of the radius skirt is introduced. Unlike Rs, the results show that Ss is a linear function versus pressure. This may help to use Ss in different scattering regimes and for a best interpretation of the consequences of electron scattering beam by gaseous environment. For demonstration, two gases environment: helium and water vapor are given but the results are valid whatever the environment used.展开更多
A numerical model was developed by using the dual boundary element method to investigate the dynamic behavior of a moored floating structure with a pair of vertical and flexible skirts attached at its bottom in the li...A numerical model was developed by using the dual boundary element method to investigate the dynamic behavior of a moored floating structure with a pair of vertical and flexible skirts attached at its bottom in the linear wave field. Theoretical conception is based on potential theory with linear external forces. The motions of the structure were assumed to be small and linear. The flexible skirts mounted beneath the structure were assumed uniform flexural rigidity and the thickness of the skirts was negligible. Comparison between the present model and Gesraha＇s solution was made to verify the results for a moored floating structure with or without rigid skirts. The influence of the skirt rigidity on the moored floating structure, moored lines and waves is investigated in this study. The results show that, the natural frequencies of structure＇s oscillation, moored force, wave reflection and transmission tend to the region of short-period waves when the flexible rigidity gradually decreases. Positive correlation exists between the aft mooring force and the pitch motion of the floating structure.展开更多
To eliminate the defects during piston skirt isothermal forming process,simulations under different process parameters such as the deformation temperature and friction factor were analyzed with the rigid-plastic FEA.D...To eliminate the defects during piston skirt isothermal forming process,simulations under different process parameters such as the deformation temperature and friction factor were analyzed with the rigid-plastic FEA.Deformation pattern,metal flow and influence of process parameters were concluded.The prediction load value with a relative error of 4.98% is more accurate to the testing one than that from the empirical formula whose relative error is up to 50.8%.Finally,based on the simulation results,an improved process at 300 ℃ and 0.005-0.05 s-1 was verified without any defects by the physical try-out.展开更多
基金financially supported by the National Natural Science Foundation of China(Grant No.51078227)Shandong Natural Science Foundation(Grant No.ZR2009FM003)
文摘Monotonic lateral load model tests were carried out on steel skirted suction caissons embedded in the saturated medium sand to study the bearing capacity. A three-dimensional continuum finite element model was developed with Z_SOIL software. The numerical model was calibrated against experimental results. Soil deformation and earth pressures on skirted caissons were investigated by using the finite element model to extend the model tests. It shows that the ＂skirted＂ structure can significantly increase the lateral capacity and limit the deflection, especially suitable for offshore wind turbines, compared with regular suction caissons without the ＂skirted＂ at the same load level. In addition, appropriate determination of rotation centers plays a crucial role in calculating the lateral capacity by using the analytical method. It was also found that the rotation center is related to dimensions of skirted suction caissons and loading process, i.e. the rotation center moves upwards with the increase of the ＂skirted＂ width and length; moreover, the rotation center moves downwards with the increase of loading and keeps constant when all the sand along the caisson＇s wall yields. It is so complex that we cannot simply determine its position like the regular suction caisson commonly with a specified position to the length ratio of the caisson.
文摘Based on the rigid-plastic theory, the finite element method (FEM) equation which incorporates the influence of impact load and volume force is presented. The hammer forging theory for simulation is also given. On the basis of technological analyses, the piston skirt forging processes of LD11 aluminium alloy are simulated under both mechanical pressure forging and hammer forging conditions. By comparison with the metal flow, fibre flow lines, distributions of strain and temperature of the two forging methods, practical forging was carried out and the product quality was controlled. The deformation pattern of the piston skirt forging process was determined by comparing the simulation results with the practical forging results.
基金Sponsored by the National Science&Technology Pillar Program During the 12th Five-year Plan Period(Grant No.2015BAD17B03)Subject Construction Fund Guided by HIT(Grant No.WH20150206,WH20160206)Key Research and Development Plan of Shandong Province(Grant No.2015GSF115016)
文摘The processes of scallop meats can produce a large amount of by-products like scallop skirts,which are rich in nutrients. This work aimed to obtain the information about antioxidant peptides derived from scallop skirts of Mimachlamys nobilis. The hydro-lysates obtained by trypsin exhibited the highest antioxidant activity( 75.6%,79.5% and 76.7% using DPPH,hydroxyl and superoxide anion radical scavenging activity assays,respectively). The antioxidant peptides( MNAP) were separated and purified using UF membranes,GFC processes and RP-HPLC,and the antioxidant activity of MNAP was identified to be 85.7% using DPPH radical scavenging activity assay. The peptides( MNAP) were composed of two peptides with their molecular weights2 855.6 Da and 3 007.2 Da using MALDI-TOF-MS,respectively. The results suggested that the scallop skirts of Mimachlamys nobilis could be explored as a source of antioxidant peptides.
文摘The influence of oil film inertia on piston skirt lubrication in a high speedengine is investigated by an iteration method that alternately solves the Navier-Stocks equationsand the Reynolds equa-tion by finite element method and difference method. The Reynolds lubricationequation including oil film inertia is developed, in which the inertia coefficient is introduced toinvestigate the effect of oil film inertia. The iteration procedure and finite formulation ofsolving the new Reynolds lubrication equation are given to analyze the effect of oil film on pistonskirt in this kind of engine. The calculation results show that the oil film inertia has someeffects on the friction force, pressure force and load capacity of oil film and its effect isobvious for the last. The Reynolds lubrication equation proposed can be also used to analyze thelubrication performance of the piston skirt in low or medium speed engine and some other lubricationproblems generally excluding oil film inertia with the inertia coefficient being set at zero.
基金National Natural Science Foundation of China (Grant No. 59990472)
文摘By an iteration method, the influence of oil film inertia on piston skirt lubrication in a high speed engine is investigated. By alternately solving the Navier-Stocks equations and the Reynolds equation, the new iteration method can trace the variations of velocity field and pressure field with time. Based on this, the mixed-lubrication model suitable for the piston skirt of high engines is proposed. By introducing the inertia coefficient, the new lubrication model includes the inertia term in oil film. The model can be also used to solve for the lubrication performances of a piston skirt in low or medium speed engines and for lubrication problem in general excluding the inertia term of oil film , when the inertia coefficient is put equal to zero. The calculation results show that the influence of oil film inertia on the friction force increases with the ratio of the piston skirt's length to its diameter, the inertia coefficient and the eccentricities of the lower and the upper piston skirt, with other conditions kept constant, while the influence of it on the load capacity of oil film is small.
文摘A mixed lubrication model was established for piston skirt lubrication. The mathematical model developed in this paper incorporates governing equations of motion with average Reynolds equation. This model considers the surfaceroughness and profile. The corresponding computer program can be used to calculate oscillatory motion of piston during the entire trajectory, which has the excellent convergence.In addition, a set of equipment, which adopt the laser induced fluorescent method, was developed to measure the oil film thickness between the piston and the bore.
文摘In this work, a novel parameter called the surface skirt (Ss) is introduced. The electron beam scattering by gaseous environment is the fundamental parameter limiting the performance of the Gaseous Scanning Electron Microscopy (GSEM). The result is the enlargement of the primary beam characterized by the radius skirt Rs. The scattering phenomena require a much closer re-examination. In fact, depending on the localization of EDX detector and the particles shape to analyze, the collected signal after the beam skirt will be different and Rs also will be different. So, except for homogeneous materials, Rs can not describe the scattering behavior. In this study, the surface skirt Ss instead of the radius skirt is introduced. Unlike Rs, the results show that Ss is a linear function versus pressure. This may help to use Ss in different scattering regimes and for a best interpretation of the consequences of electron scattering beam by gaseous environment. For demonstration, two gases environment: helium and water vapor are given but the results are valid whatever the environment used.
文摘A numerical model was developed by using the dual boundary element method to investigate the dynamic behavior of a moored floating structure with a pair of vertical and flexible skirts attached at its bottom in the linear wave field. Theoretical conception is based on potential theory with linear external forces. The motions of the structure were assumed to be small and linear. The flexible skirts mounted beneath the structure were assumed uniform flexural rigidity and the thickness of the skirts was negligible. Comparison between the present model and Gesraha＇s solution was made to verify the results for a moored floating structure with or without rigid skirts. The influence of the skirt rigidity on the moored floating structure, moored lines and waves is investigated in this study. The results show that, the natural frequencies of structure＇s oscillation, moored force, wave reflection and transmission tend to the region of short-period waves when the flexible rigidity gradually decreases. Positive correlation exists between the aft mooring force and the pitch motion of the floating structure.
文摘To eliminate the defects during piston skirt isothermal forming process,simulations under different process parameters such as the deformation temperature and friction factor were analyzed with the rigid-plastic FEA.Deformation pattern,metal flow and influence of process parameters were concluded.The prediction load value with a relative error of 4.98% is more accurate to the testing one than that from the empirical formula whose relative error is up to 50.8%.Finally,based on the simulation results,an improved process at 300 ℃ and 0.005-0.05 s-1 was verified without any defects by the physical try-out.
