The dynamics of jacket supported offshore wind turbine （OWT） in earthquake environment is one of the progressing focuses in the renewable energy field. Soil-structure interaction （SSI） is a fundamental principle t...The dynamics of jacket supported offshore wind turbine （OWT） in earthquake environment is one of the progressing focuses in the renewable energy field. Soil-structure interaction （SSI） is a fundamental principle to analyze stability and safety of the structure. This study focuses on the performance of the multiple tuned mass damper （MTMD） in minimizing the dynamic responses of the structures objected to seismic loads combined with static wind and wave loads. Response surface methodology （RSM） has been applied to design the MTMD parameters. The analyses have been performed under two different boundary conditions： fixed base （without SSI） and flexible base （with SSI）. Two vibration modes of the structure have been suppressed by multi-mode vibration control principle in both cases. The effectiveness of the MTMD in reducing the dynamic response of the structure is presented. The dynamic SSI plays an important role in the seismic behavior of the jacket supported OWT, especially resting on the soft soil deposit. Finally, it shows that excluding the SSI effect could be the reason of overestimating the MTMD performance.展开更多
Active multiple tuned mass dampers （referred to as AMTMD）, which consist of several active tuned mass dampers （ATMDs） with identical stiffness and damping coefficients but varying mass and control force, have rece...Active multiple tuned mass dampers （referred to as AMTMD）, which consist of several active tuned mass dampers （ATMDs） with identical stiffness and damping coefficients but varying mass and control force, have recently been proposed to suppress undesirable oscillations of structures under ground acceleration. It has been shown that the AMTMD can remarkably improve the performance of multiple tuned mass dampers （MTMDs） and is also more effective in reducing structure oscillation than single ATMDs. Notwithstanding this, good performance of AMTMD （including a single ATMD illustrated from frequency-domain analysis） may not necessarily translate into a good seismic reduction behavior in the time-domain. To investigate these phenomena, a three-story steel structure model controlled by AMTMD with three ATMDs was implemented in SIMULINK and subjected to several historical earthquakes. Likewise, the structure under consideration was assumed to have uncertainty of stiffness, such as 4-15% of its initial stiffness, in the numerical simulations. The optimum design parameters of the AMTMD were obtained in the frequency-domain by implementing the minimization of the minimum values of the maximum dynamic magnification factors （DMF） of general structures with AMTMD. For comparison purposes, response analysis of the same structure with a single ATMD was also performed. The numerical analysis and comparison show that the AMTMD generally renders better effectiveness when compared with a single ATMD for structures subjected to historical earthquakes. In particular, the AMTMD can improve the effectiveness of a single ATMD for a structure with an uncertainty of stiffness of 4-15% of its initial stiffness.展开更多
Trichoderma species have shown efficiency on biocontrol of phytopathogens.For commercial application,it must be propagated in mass scale using a cost-effective method.As an alternative way to effectively deliver bioco...Trichoderma species have shown efficiency on biocontrol of phytopathogens.For commercial application,it must be propagated in mass scale using a cost-effective method.As an alternative way to effectively deliver biocontrol fungi inoculum to the field;seven agro-based wastes including rice bran,biochar,empty fruit bunches,coconut fibre,compost,topsoil and mixed soil were used in this study for evaluating mass multiplication of Trichoderma species.Based on the evaluation of colony-forming units(cfu)among the agro-based waste media used,coconut fibre is the most suitable in promoting the sporulation of Trichoderma asperellum and T.harzianum.Trichoderma asperellum C1667 showed the higher micropropagule count through incubation period compared to T.harzianum C1675.After 120 days on the agro-based waste media,T.asperellum C1667 and T.harzianum C1675 produced the highest(7.717×10^(5)cfu/g and 6.836±13.79×10^(5)cfu/g)coconut fibres,respectively.Meanwhile,the mixed soil appeared with the lowest cfu.Coconut fibres were shown as a great biocomposting medium for both Trichoderma species.Findings of the present study are valuable for disease management using agro-based wastes as a cost-effective medium for biocontrol agents like Trichoderma species.展开更多
基金supported by a grant[MPSS-NH-2015-78]through the DisasterSafety Management Institute funded by Ministry of Public Safety and Security of Korean government
文摘The dynamics of jacket supported offshore wind turbine （OWT） in earthquake environment is one of the progressing focuses in the renewable energy field. Soil-structure interaction （SSI） is a fundamental principle to analyze stability and safety of the structure. This study focuses on the performance of the multiple tuned mass damper （MTMD） in minimizing the dynamic responses of the structures objected to seismic loads combined with static wind and wave loads. Response surface methodology （RSM） has been applied to design the MTMD parameters. The analyses have been performed under two different boundary conditions： fixed base （without SSI） and flexible base （with SSI）. Two vibration modes of the structure have been suppressed by multi-mode vibration control principle in both cases. The effectiveness of the MTMD in reducing the dynamic response of the structure is presented. The dynamic SSI plays an important role in the seismic behavior of the jacket supported OWT, especially resting on the soft soil deposit. Finally, it shows that excluding the SSI effect could be the reason of overestimating the MTMD performance.
文摘Active multiple tuned mass dampers （referred to as AMTMD）, which consist of several active tuned mass dampers （ATMDs） with identical stiffness and damping coefficients but varying mass and control force, have recently been proposed to suppress undesirable oscillations of structures under ground acceleration. It has been shown that the AMTMD can remarkably improve the performance of multiple tuned mass dampers （MTMDs） and is also more effective in reducing structure oscillation than single ATMDs. Notwithstanding this, good performance of AMTMD （including a single ATMD illustrated from frequency-domain analysis） may not necessarily translate into a good seismic reduction behavior in the time-domain. To investigate these phenomena, a three-story steel structure model controlled by AMTMD with three ATMDs was implemented in SIMULINK and subjected to several historical earthquakes. Likewise, the structure under consideration was assumed to have uncertainty of stiffness, such as 4-15% of its initial stiffness, in the numerical simulations. The optimum design parameters of the AMTMD were obtained in the frequency-domain by implementing the minimization of the minimum values of the maximum dynamic magnification factors （DMF） of general structures with AMTMD. For comparison purposes, response analysis of the same structure with a single ATMD was also performed. The numerical analysis and comparison show that the AMTMD generally renders better effectiveness when compared with a single ATMD for structures subjected to historical earthquakes. In particular, the AMTMD can improve the effectiveness of a single ATMD for a structure with an uncertainty of stiffness of 4-15% of its initial stiffness.
基金supported by the Putra Grant(IPS),Universiti Putra Malaysia[grant numbers UPM/700-2/1/GP-IPS/2017/9577700].
文摘Trichoderma species have shown efficiency on biocontrol of phytopathogens.For commercial application,it must be propagated in mass scale using a cost-effective method.As an alternative way to effectively deliver biocontrol fungi inoculum to the field;seven agro-based wastes including rice bran,biochar,empty fruit bunches,coconut fibre,compost,topsoil and mixed soil were used in this study for evaluating mass multiplication of Trichoderma species.Based on the evaluation of colony-forming units(cfu)among the agro-based waste media used,coconut fibre is the most suitable in promoting the sporulation of Trichoderma asperellum and T.harzianum.Trichoderma asperellum C1667 showed the higher micropropagule count through incubation period compared to T.harzianum C1675.After 120 days on the agro-based waste media,T.asperellum C1667 and T.harzianum C1675 produced the highest(7.717×10^(5)cfu/g and 6.836±13.79×10^(5)cfu/g)coconut fibres,respectively.Meanwhile,the mixed soil appeared with the lowest cfu.Coconut fibres were shown as a great biocomposting medium for both Trichoderma species.Findings of the present study are valuable for disease management using agro-based wastes as a cost-effective medium for biocontrol agents like Trichoderma species.
