临床预测模型开发和验证过程的完整报告对于模型外部验证及临床应用至关重要。《个体预后或诊断的多变量预测模型透明报告》(Transparent Reporting of a Multivariable Prediction Model for Individual Prognosis or Diagnosis,TRIPOD...临床预测模型开发和验证过程的完整报告对于模型外部验证及临床应用至关重要。《个体预后或诊断的多变量预测模型透明报告》(Transparent Reporting of a Multivariable Prediction Model for Individual Prognosis or Diagnosis,TRIPOD)为规范化预测模型的报告过程及报告质量评价提供了指导。本文将采用例解的形式对TRIPOD报告规范各条目进行详细解读,便于临床预测模型领域的研究者更好地掌握及应用该报告规范,进而提高预测模型的报告质量。展开更多
临床预测模型开发和验证过程的完整报告对于模型外部验证及临床应用至关重要。《个体预后或诊断的多变量预测模型透明报告》(Transparent Reporting of a Multivariable Prediction Model for Individual Prognosis or Diagnosis,TRIPOD...临床预测模型开发和验证过程的完整报告对于模型外部验证及临床应用至关重要。《个体预后或诊断的多变量预测模型透明报告》(Transparent Reporting of a Multivariable Prediction Model for Individual Prognosis or Diagnosis,TRIPOD)为规范化预测模型的报告过程及报告质量评价提供了指导。本文将采用例解的形式对TRIPOD报告规范各条目进行详细解读,便于临床预测模型领域的研究者更好地掌握及应用该报告规范,进而提高预测模型的报告质量。展开更多
Fixed offshore wind turbines usually have large underwater supporting structures. The fluid influences the dynamic characteristics of the structure system. The dynamic model of a 5-MW tripod offshore wind turbine cons...Fixed offshore wind turbines usually have large underwater supporting structures. The fluid influences the dynamic characteristics of the structure system. The dynamic model of a 5-MW tripod offshore wind turbine considering the pile-soil system and fluid structure interaction （FSI） is established, and the structural modes in air and in water are obtained by use of ANSYS. By comparing low-order natural frequencies and mode shapes, the influence of sea water on the free vibration characteristics of offshore wind turbine is analyzed. On basis of the above work, seismic responses under excitation by E1-Centro waves are calculated by the time-history analysis method. The results reveal that the dynamic responses such as the lateral displacement of the foundation and the section bending moment of the tubular piles increase substantially under the influence of the added-mass and hydrodynamic pressure of sea water. The method and conclusions presented in this paper can provide a theoretical reference for structure design and analysis of offshore wind turbines fixed in deep seawater.展开更多
In estuarine and coastal areas, the seabed is in a constant process of dynamic change under marine conditions.Seabed sediment erosion and resuspension are important processes that safely control the geological environ...In estuarine and coastal areas, the seabed is in a constant process of dynamic change under marine conditions.Seabed sediment erosion and resuspension are important processes that safely control the geological environment. Field tripod observations conducted in the Jiaozhou Bay in China are reported, to investigate the effects of hydrodynamic conditions on the erosion and resuspension processes of the seabed. The observational results show that the maximum shear stress created by tidal currents can reach 0.35 N/m2, which is higher than the wave-induced shear stress during fair weather conditions. A seabed erosion frequently occurs during the flood tide, whereas a seabed deposition occurs during ebb tide. Waves can produce a bottom shear stress approximately equivalent to that induced by currents when the local wind reaches Force 4 with a speed of 5 m/s.When the wind reaches 7 m/s and the significant wave height reaches 26 cm, waves play a more significant role than currents in the dynamic processes of the seabed sediment resuspension and lead to a high value of turbidity that is approximately two to eight times higher than that in fair weather. These analyses clearly illustrate that periodic current-induced sediment erosion and resuspension are dominant in fair weather, whereas episodic high waves are responsible for significant sediment resuspension. Additional work is needed to establish a more thorough understanding of the mechanisms of sediment dynamics in the Jiaozhou Bay.展开更多
In this study,model tests were conducted to investigate the bearing capacities of tripod caisson foundations subjected to eccentric lateral loads in silty clay.Lateral load–rotation curves of five eccentric-shaped tr...In this study,model tests were conducted to investigate the bearing capacities of tripod caisson foundations subjected to eccentric lateral loads in silty clay.Lateral load–rotation curves of five eccentric-shaped tripod suction foundations were plotted to analyze the bearing capacities at different loading angles.It was observed that the loading angle significantly influenced the bearing capacity of the foundations,particularly for eccentric tripod caisson foundations.Compared with eccentric tripod caisson foundations,the traditional tripod foundation has a relatively high ultimate lateral capacity at the omnidirectional loading angle.By analyzing the displacement of the caissons,a formula for the rotational center of the tripod caisson foundation subjected to an eccentric lateral load was derived.The depth of the rotation center was 0.68–0.92 times the height of the caisson when the bearing capacity reached the limit.Under the undrained condition,suction was generated under the lid of the“up-lift”caisson,which helps resist lateral forces from the wind and waves.展开更多
文摘临床预测模型开发和验证过程的完整报告对于模型外部验证及临床应用至关重要。《个体预后或诊断的多变量预测模型透明报告》(Transparent Reporting of a Multivariable Prediction Model for Individual Prognosis or Diagnosis,TRIPOD)为规范化预测模型的报告过程及报告质量评价提供了指导。本文将采用例解的形式对TRIPOD报告规范各条目进行详细解读,便于临床预测模型领域的研究者更好地掌握及应用该报告规范,进而提高预测模型的报告质量。
文摘临床预测模型开发和验证过程的完整报告对于模型外部验证及临床应用至关重要。《个体预后或诊断的多变量预测模型透明报告》(Transparent Reporting of a Multivariable Prediction Model for Individual Prognosis or Diagnosis,TRIPOD)为规范化预测模型的报告过程及报告质量评价提供了指导。本文将采用例解的形式对TRIPOD报告规范各条目进行详细解读,便于临床预测模型领域的研究者更好地掌握及应用该报告规范,进而提高预测模型的报告质量。
基金financially supported by the Fund for Creative Research Groups of China(Grant No.51421064)
文摘Fixed offshore wind turbines usually have large underwater supporting structures. The fluid influences the dynamic characteristics of the structure system. The dynamic model of a 5-MW tripod offshore wind turbine considering the pile-soil system and fluid structure interaction （FSI） is established, and the structural modes in air and in water are obtained by use of ANSYS. By comparing low-order natural frequencies and mode shapes, the influence of sea water on the free vibration characteristics of offshore wind turbine is analyzed. On basis of the above work, seismic responses under excitation by E1-Centro waves are calculated by the time-history analysis method. The results reveal that the dynamic responses such as the lateral displacement of the foundation and the section bending moment of the tubular piles increase substantially under the influence of the added-mass and hydrodynamic pressure of sea water. The method and conclusions presented in this paper can provide a theoretical reference for structure design and analysis of offshore wind turbines fixed in deep seawater.
基金The National Natural Science Foundation of China under contract Nos 41402253,41427803 and 41372287the Project of Qingdao National Laboratory for Marine Science and Technology under contract No.QNLM2016ORP0110
文摘In estuarine and coastal areas, the seabed is in a constant process of dynamic change under marine conditions.Seabed sediment erosion and resuspension are important processes that safely control the geological environment. Field tripod observations conducted in the Jiaozhou Bay in China are reported, to investigate the effects of hydrodynamic conditions on the erosion and resuspension processes of the seabed. The observational results show that the maximum shear stress created by tidal currents can reach 0.35 N/m2, which is higher than the wave-induced shear stress during fair weather conditions. A seabed erosion frequently occurs during the flood tide, whereas a seabed deposition occurs during ebb tide. Waves can produce a bottom shear stress approximately equivalent to that induced by currents when the local wind reaches Force 4 with a speed of 5 m/s.When the wind reaches 7 m/s and the significant wave height reaches 26 cm, waves play a more significant role than currents in the dynamic processes of the seabed sediment resuspension and lead to a high value of turbidity that is approximately two to eight times higher than that in fair weather. These analyses clearly illustrate that periodic current-induced sediment erosion and resuspension are dominant in fair weather, whereas episodic high waves are responsible for significant sediment resuspension. Additional work is needed to establish a more thorough understanding of the mechanisms of sediment dynamics in the Jiaozhou Bay.
基金The work presented in this paper was supported by the National Natural Science Foundation of China(Grant No.51479137).
文摘In this study,model tests were conducted to investigate the bearing capacities of tripod caisson foundations subjected to eccentric lateral loads in silty clay.Lateral load–rotation curves of five eccentric-shaped tripod suction foundations were plotted to analyze the bearing capacities at different loading angles.It was observed that the loading angle significantly influenced the bearing capacity of the foundations,particularly for eccentric tripod caisson foundations.Compared with eccentric tripod caisson foundations,the traditional tripod foundation has a relatively high ultimate lateral capacity at the omnidirectional loading angle.By analyzing the displacement of the caissons,a formula for the rotational center of the tripod caisson foundation subjected to an eccentric lateral load was derived.The depth of the rotation center was 0.68–0.92 times the height of the caisson when the bearing capacity reached the limit.Under the undrained condition,suction was generated under the lid of the“up-lift”caisson,which helps resist lateral forces from the wind and waves.
