Wind direction forecasting plays an important role in wind power prediction and air pollution management. Weather quantities such as temperature, precipitation, and wind speed are linear variables in which traditional...Wind direction forecasting plays an important role in wind power prediction and air pollution management. Weather quantities such as temperature, precipitation, and wind speed are linear variables in which traditional model output statistics and bias correction methods are applied. However, wind direction is an angular variable; therefore, such traditional methods are ineffective for its evaluation. This paper proposes an effective bias correction technique for wind direction forecasting of turbine height from numerical weather prediction models, which is based on a circular-circular regression approach. The technique is applied to a 24-h forecast of 65-m wind directions observed at Yangmeishan wind farm, Yunnan Province, China, which consistently yields improvements in forecast performance parameters such as smaller absolute mean error and stronger similarity in wind rose diagram pattern.展开更多
This article describes model of human eye fluctuations such as refraction etc. and makes its physical interpretation. Because mistakes in refraction measurements correspond to fluctuations in eye's focus, it is possi...This article describes model of human eye fluctuations such as refraction etc. and makes its physical interpretation. Because mistakes in refraction measurements correspond to fluctuations in eye's focus, it is possible to calculate theoretical limits for the best accuracy in measurements of eye's refraction (0.25-0.3 D). Optical model for astigmatic human eye predicts possibility only 70% compensation of visual acuity by cylindrical glasses. New data and methods for digital measuring of color and gray vision were tested, too. Also ,some new results and model for periphery color and grey vision were proposed and discussed.展开更多
A new type energy absorber was introduced,which is composed of thousands of thin ring plates with different diameters.Because it can switch the impact to thousands of shearing actions among thin ring plates inside the...A new type energy absorber was introduced,which is composed of thousands of thin ring plates with different diameters.Because it can switch the impact to thousands of shearing actions among thin ring plates inside the absorber,the impact energy is decentralized and dissipated gradually,the impact acting time is extended and the peak of acceleration is reduced obviously.Numerical simulations by finite element method (FEM) coupled with smoothed particle hydrodynamics (SPH) method were preformed to predict the energy absorption characteristics.Energy absorption ability with different impact velocities was studied and the effects of thickness and material of ring plates were discussed.The sled crash test was carried out to validate the result of simulations.The new type absorber is effective for collision that impact velocity is lower than 40 km/h.展开更多
The November 14,2001 M_S8.1 Kunlun Mountains earthquake in northern Tibet is the largest earthquake occurring on the Chinese mainland since 1950.We apply a three-dimensional(3-D)finite element numerical procedure to m...The November 14,2001 M_S8.1 Kunlun Mountains earthquake in northern Tibet is the largest earthquake occurring on the Chinese mainland since 1950.We apply a three-dimensional(3-D)finite element numerical procedure to model the coseismic displacement and stress fields of the earthquake based on field investigations.We then further investigate the stress interaction between the M_S8.1 earthquake and the intensive aftershocks.Our primary calculation shows that the coseismic displacement field is centralized around the east Kunlun fault zone.And the attenuation of coseismic displacements on the south side of Kunlun fault zone is larger than that on the north side.The calculated coseismic stress field also indicates that the calculated maximal shear stress field is centralized around the east Kunlun fault zone;the directions of the coseismic major principal stress are opposite to that of the background crustal stress field of the Qinghai-Xizang(Tibet)Plateau.It indicates that the earthquake relaxes the crustal stress state in the Qinghai-Xizang(Tibet)Plateau.Finally,we study the stress interaction between M_S8.1 earthquake and its intensive aftershocks.The calculated Coulomb stress changes of the M_S8.1 great earthquake are in favor of triggering 4 aftershocks.展开更多
Efficient numerical solver for the SchrSdinger equation is very important in physics and chemistry. The finite element discrete variable representation (FE-DVR) was first proposed by Rescigno and Mc-Curdy [Phys. Rev...Efficient numerical solver for the SchrSdinger equation is very important in physics and chemistry. The finite element discrete variable representation (FE-DVR) was first proposed by Rescigno and Mc-Curdy [Phys. Rev. A 62, 032706 (2000)] for solving quantum-mechanical scattering problems. In this work, an FE-DVR method in a mapped coordinate was proposed to improve the efficiency of the original FE-DVR method. For numerical demonstration, the proposed approach is applied for solving the electronic eigenfunctions and eigenvalues of the hydrogen atom and vibrational states of the electronic state 3E+ of the Cs2 molecule which has long-range interaction potential. The numerical results indicate that the numerical efficiency of the original FE-DVR has been improved much using our proposed mapped coordinate scheme.展开更多
This paper will discuss one topic in the current debate on higher education: How power is exercised between universities? How do colleges determine what the best college is? What are the differences in the excersis...This paper will discuss one topic in the current debate on higher education: How power is exercised between universities? How do colleges determine what the best college is? What are the differences in the excersise of power in the digital age? The authors analyze one of the mechanisms of relationship and contact between different universities: the rankings. They will discuss the practices that allow certain values and organizations they are becoming central nodes between universities and the influences of the information and communication technologies in the measurement mechanisms. The authors seek to show the rankings serve as mechanisms to exercise power among universities. These measurements become a tool and justification in competition between universities for resources such as funding, prestige, and student demand. The analysis is based on the University of Mexico, the authors use the ranking of the best universities in Latin America and the best universities in Mexico.展开更多
基金supported by the Strategic Priority Research Program-Climate Change: Carbon Budget and Related Issues of the Chinese Academy of Sciences (Grant No. XDA05040301)the National Basic Research Program of China (Grant No. 2010CB951804)the National Natural Science Foundation of China (Grant No. 41101045)
文摘Wind direction forecasting plays an important role in wind power prediction and air pollution management. Weather quantities such as temperature, precipitation, and wind speed are linear variables in which traditional model output statistics and bias correction methods are applied. However, wind direction is an angular variable; therefore, such traditional methods are ineffective for its evaluation. This paper proposes an effective bias correction technique for wind direction forecasting of turbine height from numerical weather prediction models, which is based on a circular-circular regression approach. The technique is applied to a 24-h forecast of 65-m wind directions observed at Yangmeishan wind farm, Yunnan Province, China, which consistently yields improvements in forecast performance parameters such as smaller absolute mean error and stronger similarity in wind rose diagram pattern.
文摘This article describes model of human eye fluctuations such as refraction etc. and makes its physical interpretation. Because mistakes in refraction measurements correspond to fluctuations in eye's focus, it is possible to calculate theoretical limits for the best accuracy in measurements of eye's refraction (0.25-0.3 D). Optical model for astigmatic human eye predicts possibility only 70% compensation of visual acuity by cylindrical glasses. New data and methods for digital measuring of color and gray vision were tested, too. Also ,some new results and model for periphery color and grey vision were proposed and discussed.
文摘A new type energy absorber was introduced,which is composed of thousands of thin ring plates with different diameters.Because it can switch the impact to thousands of shearing actions among thin ring plates inside the absorber,the impact energy is decentralized and dissipated gradually,the impact acting time is extended and the peak of acceleration is reduced obviously.Numerical simulations by finite element method (FEM) coupled with smoothed particle hydrodynamics (SPH) method were preformed to predict the energy absorption characteristics.Energy absorption ability with different impact velocities was studied and the effects of thickness and material of ring plates were discussed.The sled crash test was carried out to validate the result of simulations.The new type absorber is effective for collision that impact velocity is lower than 40 km/h.
基金The research was sponsored by the"Basic Scientific Research Plan"(02076902-03) of Institute of Earthquake Science, China Earthquake Administrationby grants from the Chinese Ministry of Science and Technology (2004CB418406, 2005DKA64000).
文摘The November 14,2001 M_S8.1 Kunlun Mountains earthquake in northern Tibet is the largest earthquake occurring on the Chinese mainland since 1950.We apply a three-dimensional(3-D)finite element numerical procedure to model the coseismic displacement and stress fields of the earthquake based on field investigations.We then further investigate the stress interaction between the M_S8.1 earthquake and the intensive aftershocks.Our primary calculation shows that the coseismic displacement field is centralized around the east Kunlun fault zone.And the attenuation of coseismic displacements on the south side of Kunlun fault zone is larger than that on the north side.The calculated coseismic stress field also indicates that the calculated maximal shear stress field is centralized around the east Kunlun fault zone;the directions of the coseismic major principal stress are opposite to that of the background crustal stress field of the Qinghai-Xizang(Tibet)Plateau.It indicates that the earthquake relaxes the crustal stress state in the Qinghai-Xizang(Tibet)Plateau.Finally,we study the stress interaction between M_S8.1 earthquake and its intensive aftershocks.The calculated Coulomb stress changes of the M_S8.1 great earthquake are in favor of triggering 4 aftershocks.
文摘Efficient numerical solver for the SchrSdinger equation is very important in physics and chemistry. The finite element discrete variable representation (FE-DVR) was first proposed by Rescigno and Mc-Curdy [Phys. Rev. A 62, 032706 (2000)] for solving quantum-mechanical scattering problems. In this work, an FE-DVR method in a mapped coordinate was proposed to improve the efficiency of the original FE-DVR method. For numerical demonstration, the proposed approach is applied for solving the electronic eigenfunctions and eigenvalues of the hydrogen atom and vibrational states of the electronic state 3E+ of the Cs2 molecule which has long-range interaction potential. The numerical results indicate that the numerical efficiency of the original FE-DVR has been improved much using our proposed mapped coordinate scheme.
文摘This paper will discuss one topic in the current debate on higher education: How power is exercised between universities? How do colleges determine what the best college is? What are the differences in the excersise of power in the digital age? The authors analyze one of the mechanisms of relationship and contact between different universities: the rankings. They will discuss the practices that allow certain values and organizations they are becoming central nodes between universities and the influences of the information and communication technologies in the measurement mechanisms. The authors seek to show the rankings serve as mechanisms to exercise power among universities. These measurements become a tool and justification in competition between universities for resources such as funding, prestige, and student demand. The analysis is based on the University of Mexico, the authors use the ranking of the best universities in Latin America and the best universities in Mexico.