The interaction between climate and vegetation along four Pole-Equator-Pole （PEP） belts were explored using a global two-way coupled model, AVIM-GOALS, which links the ecophysiological processes at the land surface ...The interaction between climate and vegetation along four Pole-Equator-Pole （PEP） belts were explored using a global two-way coupled model, AVIM-GOALS, which links the ecophysiological processes at the land surface with the general circulation model （GCM）. The PEP belts are important in linking the climate change with the variation of sea and land, including terrestrial ecosystems. Previous PEP belts studies have mainly focused on the paleoclimate variation and its reconstruction. This study analyzes and discusses the interaction between modern climate and vegetation represented by leaf area index （LAI） and net primary production （NPP）. The results show that the simulated LAI variation, corresponding to the observed LAI variation, agrees with the peak-valley variation of precipitation in these belts. The annual mean NPP simulated by the coupled model is also consistent with PIK NPP data in its overall variation trend along the four belts, which is a good example to promote global ecological studies by coupling the climate and vegetation models. A large discrepancy between the simulated and estimated LAI emerges to the south of 15°N along PEP 3 and to the south of 18°S in PEP 1S, and the discrepancy for the simulated NPP and PIK data in the two regions is relatively smaller in contrast to the LAI difference. Precipitation is a key factor affecting vegetation variation, and the overall trend of LAI and NPP corresponds more obviously to precipitation variation than temperature change along most parts of these PEP belts.展开更多
Denurcioslu et al. presented a method named continuous-time general-ized predictive control(CGPC) in 1991, which is obtained on the basis of the mini-mization of a quadratic cost function. However, In engineering prac...Denurcioslu et al. presented a method named continuous-time general-ized predictive control(CGPC) in 1991, which is obtained on the basis of the mini-mization of a quadratic cost function. However, In engineering practice, the behav-ior of a control system is generally evaluated by observing its dynamic response con-cerned mainly with the clused-loup poles uf the system. A CGPC algorithm withclosed-loop pole-placement is propused in this paper which advances the results byDemircioglu et al.展开更多
By means of programs GTMPAC based on generalized triangle method,analysisand synthesis of mechanism design in accordance with absolutely graphical method( absolutely germetrical method) are developed.In this paper,we ...By means of programs GTMPAC based on generalized triangle method,analysisand synthesis of mechanism design in accordance with absolutely graphical method( absolutely germetrical method) are developed.In this paper,we make a specialstudy about Burmester’s curve.展开更多
The accuracy of brackets placement is a key factor in successful orthodontic therapy. An in vitro study was conducted in ten models from a natural maxillary teeth model in order to compare the accuracy of brac- kets p...The accuracy of brackets placement is a key factor in successful orthodontic therapy. An in vitro study was conducted in ten models from a natural maxillary teeth model in order to compare the accuracy of brac- kets placement between two direct bonding instru- ments: the Pole-like Bracket Positioning Gauge and the Star-like Bracket Positioning Gauge. Our results have shown that: The Star-like Bracket Positioning Gauge is more precise in placing brackets vertically, whereas the Pole-like Bracket Positioning Gauge al-lows a better angulation of the bracket. Considering each tooth separately, there is no statistically signifi-cant difference between the two positioning gauges, except that the Star-like gauge gives better results in bracket’s height for the second premolar and the ca-nine, whereas the Pole-like gauge allows for a better positioning and a better vertical angulation of the brackets for the lateral incisor. No statistically signi- ficant difference was found between the two gauges on the mesiodistal position. Overall, the Star-like gau- ge showed a better accuracy in positioning brackets.展开更多
The aim of the present work is to illustrate the application of mixed H2/H∞ control theory with Pole-Placement in de- signing controller for semi-active suspension system. It is well known that the ride comfort is im...The aim of the present work is to illustrate the application of mixed H2/H∞ control theory with Pole-Placement in de- signing controller for semi-active suspension system. It is well known that the ride comfort is improved by reducing vehicle body acceleration generated by road disturbance. In order to study this phenomenon, Two Degrees of Freedom (DOF) in state space vehicle model was built in. However, the role of H is to minimize the disturbance effect on the output while H2 is used to improve the input of controller. Linear Matrix Inequality (LMI) technique is used to calculate the dynamic controller parameters. The simulation results show that the H2 and H techniques can effectively control the vibration of vehicle system where the reduction of suspension working space, dynamic tire load and body acceleration. Moreover, the simulation results show that the (RMS) of suspension working space was reduced by 44.5%, body acceleration and dynamic tire load are reduced by 18.5% and 20% respectively.展开更多
The output of charge sensitive amplifier(CSA) is a negative exponential signal with long decay time which will result in undershoot after C-R differentiator.Pole-zero cancellation(PZC) circuit is often applied to elim...The output of charge sensitive amplifier(CSA) is a negative exponential signal with long decay time which will result in undershoot after C-R differentiator.Pole-zero cancellation(PZC) circuit is often applied to eliminate undershoot in many radiation detectors.However,it is difficult to use a zero created by PZC circuit to cancel a pole in CSA output signal accurately because of the influences of electronic components inherent error and environmental factors.A novel recursive model for PZC circuit is presented based on Kirchhoff's Current Law(KCL) in this paper.The model is established by numerical differentiation algorithm between the input and the output signal.Some simulation experiments for a negative exponential signal are carried out using Visual Basic for Application(VBA) program and a real x-ray signal is also tested.Simulated results show that the recursive model can reduce the time constant of input signal and eliminate undershoot.展开更多
利用精确解析模型生成的数据可辅助构建数值仿真样本集,为代理模型提供高质量训练数据,从而在降低计算成本的同时提升多目标优化效率。但现有解析建模常受电机拓扑约束,适用范围有限。为此,该文提出一种基于几何相似性迁移学习的电机代...利用精确解析模型生成的数据可辅助构建数值仿真样本集,为代理模型提供高质量训练数据,从而在降低计算成本的同时提升多目标优化效率。但现有解析建模常受电机拓扑约束,适用范围有限。为此,该文提出一种基于几何相似性迁移学习的电机代理模型优化方法。首先,依据物理结构之间的几何相似性构建易于精确解析化的相似电机;随后,建立相似电机设计变量-优化目标的解析映射模型并开展灵敏度分析;进而,对设计变量分层,将变量空间划分为高-低灵敏度子空间,以提高相似电机迁移结果与原型优化结果的一致性。少变量的高灵敏度参数空间通过原电机有限元分析(finite element analysis,FEA)数据建立常规代理模型进行优化,而多变量的低灵敏度参数空间则基于充足的相似电机解析数据并结合少量原型电机FEA数据,利用迁移学习训练多重保真代理模型完成最终优化。所提方法突破了精确解析模型拓扑限制,降低了结构复杂电机解析建模难度,并通过分层优化策略结合多重保真迁移显著提升高维优化效率,在保证精度前提下大幅减少计算量。该方法已用于内置式交替极永磁游标电机多目标优化,样机试验验证了有效性。展开更多
基金This study was supported by the State Key Basic Development Planning Project ＂the Development and Application of a Regional Model of the Earth System （Grant No. 2006CB400506）＂ the Innovation Project of the Chinese Academy of Sciences （Grant No. KZCX3-SW-229）the National Natural Science Foundation of China （Grant No. 40205013）.
文摘The interaction between climate and vegetation along four Pole-Equator-Pole （PEP） belts were explored using a global two-way coupled model, AVIM-GOALS, which links the ecophysiological processes at the land surface with the general circulation model （GCM）. The PEP belts are important in linking the climate change with the variation of sea and land, including terrestrial ecosystems. Previous PEP belts studies have mainly focused on the paleoclimate variation and its reconstruction. This study analyzes and discusses the interaction between modern climate and vegetation represented by leaf area index （LAI） and net primary production （NPP）. The results show that the simulated LAI variation, corresponding to the observed LAI variation, agrees with the peak-valley variation of precipitation in these belts. The annual mean NPP simulated by the coupled model is also consistent with PIK NPP data in its overall variation trend along the four belts, which is a good example to promote global ecological studies by coupling the climate and vegetation models. A large discrepancy between the simulated and estimated LAI emerges to the south of 15°N along PEP 3 and to the south of 18°S in PEP 1S, and the discrepancy for the simulated NPP and PIK data in the two regions is relatively smaller in contrast to the LAI difference. Precipitation is a key factor affecting vegetation variation, and the overall trend of LAI and NPP corresponds more obviously to precipitation variation than temperature change along most parts of these PEP belts.
文摘Denurcioslu et al. presented a method named continuous-time general-ized predictive control(CGPC) in 1991, which is obtained on the basis of the mini-mization of a quadratic cost function. However, In engineering practice, the behav-ior of a control system is generally evaluated by observing its dynamic response con-cerned mainly with the clused-loup poles uf the system. A CGPC algorithm withclosed-loop pole-placement is propused in this paper which advances the results byDemircioglu et al.
文摘By means of programs GTMPAC based on generalized triangle method,analysisand synthesis of mechanism design in accordance with absolutely graphical method( absolutely germetrical method) are developed.In this paper,we make a specialstudy about Burmester’s curve.
文摘The accuracy of brackets placement is a key factor in successful orthodontic therapy. An in vitro study was conducted in ten models from a natural maxillary teeth model in order to compare the accuracy of brac- kets placement between two direct bonding instru- ments: the Pole-like Bracket Positioning Gauge and the Star-like Bracket Positioning Gauge. Our results have shown that: The Star-like Bracket Positioning Gauge is more precise in placing brackets vertically, whereas the Pole-like Bracket Positioning Gauge al-lows a better angulation of the bracket. Considering each tooth separately, there is no statistically signifi-cant difference between the two positioning gauges, except that the Star-like gauge gives better results in bracket’s height for the second premolar and the ca-nine, whereas the Pole-like gauge allows for a better positioning and a better vertical angulation of the brackets for the lateral incisor. No statistically signi- ficant difference was found between the two gauges on the mesiodistal position. Overall, the Star-like gau- ge showed a better accuracy in positioning brackets.
文摘The aim of the present work is to illustrate the application of mixed H2/H∞ control theory with Pole-Placement in de- signing controller for semi-active suspension system. It is well known that the ride comfort is improved by reducing vehicle body acceleration generated by road disturbance. In order to study this phenomenon, Two Degrees of Freedom (DOF) in state space vehicle model was built in. However, the role of H is to minimize the disturbance effect on the output while H2 is used to improve the input of controller. Linear Matrix Inequality (LMI) technique is used to calculate the dynamic controller parameters. The simulation results show that the H2 and H techniques can effectively control the vibration of vehicle system where the reduction of suspension working space, dynamic tire load and body acceleration. Moreover, the simulation results show that the (RMS) of suspension working space was reduced by 44.5%, body acceleration and dynamic tire load are reduced by 18.5% and 20% respectively.
基金Supported by National High Technology Research and Development Program of China(863 Program)(No 2012AA061804-03)
文摘The output of charge sensitive amplifier(CSA) is a negative exponential signal with long decay time which will result in undershoot after C-R differentiator.Pole-zero cancellation(PZC) circuit is often applied to eliminate undershoot in many radiation detectors.However,it is difficult to use a zero created by PZC circuit to cancel a pole in CSA output signal accurately because of the influences of electronic components inherent error and environmental factors.A novel recursive model for PZC circuit is presented based on Kirchhoff's Current Law(KCL) in this paper.The model is established by numerical differentiation algorithm between the input and the output signal.Some simulation experiments for a negative exponential signal are carried out using Visual Basic for Application(VBA) program and a real x-ray signal is also tested.Simulated results show that the recursive model can reduce the time constant of input signal and eliminate undershoot.
文摘利用精确解析模型生成的数据可辅助构建数值仿真样本集,为代理模型提供高质量训练数据,从而在降低计算成本的同时提升多目标优化效率。但现有解析建模常受电机拓扑约束,适用范围有限。为此,该文提出一种基于几何相似性迁移学习的电机代理模型优化方法。首先,依据物理结构之间的几何相似性构建易于精确解析化的相似电机;随后,建立相似电机设计变量-优化目标的解析映射模型并开展灵敏度分析;进而,对设计变量分层,将变量空间划分为高-低灵敏度子空间,以提高相似电机迁移结果与原型优化结果的一致性。少变量的高灵敏度参数空间通过原电机有限元分析(finite element analysis,FEA)数据建立常规代理模型进行优化,而多变量的低灵敏度参数空间则基于充足的相似电机解析数据并结合少量原型电机FEA数据,利用迁移学习训练多重保真代理模型完成最终优化。所提方法突破了精确解析模型拓扑限制,降低了结构复杂电机解析建模难度,并通过分层优化策略结合多重保真迁移显著提升高维优化效率,在保证精度前提下大幅减少计算量。该方法已用于内置式交替极永磁游标电机多目标优化,样机试验验证了有效性。
