Computer simulation is a good guide and reference for development and research on petroleum refining processes. Traditionally, pseudo-components are used in the simulation, in which their physical properties are estim...Computer simulation is a good guide and reference for development and research on petroleum refining processes. Traditionally, pseudo-components are used in the simulation, in which their physical properties are estimated by empirical relations and cannot be associated with actual chemical reactions, as no molecular structure is available for pseudo-components. This limitation can be overcome if real components are used. In this paper, a real component based method is proposed for the simulation of a diesel hydrotreating process by using the software of Unisim Design. This process includes reaction units and distillation units. The chemical reaction network is established by analyzing the feedstock. The feedstock is characterized by real components, which are obtained based on true boiling point curve. Simulation results are consistent with actual data.展开更多
This paper focuses on how to extract physically meaningful information from climate data,with emphases placed on adaptive and local analysis. It is argued that many traditional statistical analysis methods with rigoro...This paper focuses on how to extract physically meaningful information from climate data,with emphases placed on adaptive and local analysis. It is argued that many traditional statistical analysis methods with rigorous mathematical footing may not be efficient in extracting essential physical information from climate data;rather,adaptive and local analysis methods that agree well with fundamental physical principles are more capable of capturing key information of climate data. To illustrate the improved power of adaptive and local analysis of climate data,we also introduce briefly the empirical mode decomposition and its later developments.展开更多
In order to uncover a possible influence on the Earth's climate, we need a much longer time series, i.e., the total solar irradiance (TSI) which is also an interesting issue in its own right in solar physics. By c...In order to uncover a possible influence on the Earth's climate, we need a much longer time series, i.e., the total solar irradiance (TSI) which is also an interesting issue in its own right in solar physics. By comparing different solar indices associated with TSI during the period 1979 to 2009, several empirical models in the TSI are presented. We verify that the reconstruction model based on the three variables: sunspot number, sunspot area, and solar 10.7 cm radio flux, is the best one. As demonstrated by model calculations, the history of TSI was reconstructed back to 1947 based on 3-indices and to 1874 based on 2-indices, respectively. The reason that the reduced irradiance on the trough during 2006 to 2009 lasts long may be due to the about 85-year cycle of solar activity, which modulates the intensity of the 11-year cycle (Schwabe cycles), possesses a considerable potential to produce an effective reducing, and holds on a steadily lower level of irradiance.展开更多
The global characteristics and trends of the tropopause physical parameters,height and temperature,obtained from the GPS/CHAMP radio occultation(RO) data in the period from Jul.2001 to Oct.2008,were modeled and analyz...The global characteristics and trends of the tropopause physical parameters,height and temperature,obtained from the GPS/CHAMP radio occultation(RO) data in the period from Jul.2001 to Oct.2008,were modeled and analyzed in this work.The global distribution and variation of these parameters with latitude were estimated and analyzed using the Empirical Orthogonal Function(EOF),which was introduced to reveal the possible relationship between the tropopause variations and global climate change.The tropopause height and temperature varied with latitude.The results obtained by using the Empirical Orthogonal Function analysis suggested a recent rise in tropopause height and decrease in tropopause temperature;and also partly supported the argument that the global rise in the tropopause is consistent with global climate change.These results also revealed that the tropopause height increased mainly in the Polar regions,particularly in the South Polar region,as well as the regions where human activity is relatively significant,and decreased in the areas that are sparsely populated or have less human activity,such as the tropic region and south hemisphere.This paper also confirms that the GPS/LEO RO data are more reliable and can be effectively used to analyze the tropopause physical parameters.展开更多
文摘Computer simulation is a good guide and reference for development and research on petroleum refining processes. Traditionally, pseudo-components are used in the simulation, in which their physical properties are estimated by empirical relations and cannot be associated with actual chemical reactions, as no molecular structure is available for pseudo-components. This limitation can be overcome if real components are used. In this paper, a real component based method is proposed for the simulation of a diesel hydrotreating process by using the software of Unisim Design. This process includes reaction units and distillation units. The chemical reaction network is established by analyzing the feedstock. The feedstock is characterized by real components, which are obtained based on true boiling point curve. Simulation results are consistent with actual data.
基金US National Science Foundation Grant(No.AGS-1139479)
文摘This paper focuses on how to extract physically meaningful information from climate data,with emphases placed on adaptive and local analysis. It is argued that many traditional statistical analysis methods with rigorous mathematical footing may not be efficient in extracting essential physical information from climate data;rather,adaptive and local analysis methods that agree well with fundamental physical principles are more capable of capturing key information of climate data. To illustrate the improved power of adaptive and local analysis of climate data,we also introduce briefly the empirical mode decomposition and its later developments.
基金supported by the National Natural Science Foundation of China (Grant No. 10978007)the Excellent Scientists Training Program of Beijing
文摘In order to uncover a possible influence on the Earth's climate, we need a much longer time series, i.e., the total solar irradiance (TSI) which is also an interesting issue in its own right in solar physics. By comparing different solar indices associated with TSI during the period 1979 to 2009, several empirical models in the TSI are presented. We verify that the reconstruction model based on the three variables: sunspot number, sunspot area, and solar 10.7 cm radio flux, is the best one. As demonstrated by model calculations, the history of TSI was reconstructed back to 1947 based on 3-indices and to 1874 based on 2-indices, respectively. The reason that the reduced irradiance on the trough during 2006 to 2009 lasts long may be due to the about 85-year cycle of solar activity, which modulates the intensity of the 11-year cycle (Schwabe cycles), possesses a considerable potential to produce an effective reducing, and holds on a steadily lower level of irradiance.
基金supported by the National High Technology Research and Development Program (Grant Nos 2008AA12A210, 2009AA122206 and 2009AA12Z319)the National Natural Science Foundation of China (Grant No10973031)the Key Research Program of Chinese Academy of Sciences (Grant No KJCX2-YZ-T13-2)
文摘The global characteristics and trends of the tropopause physical parameters,height and temperature,obtained from the GPS/CHAMP radio occultation(RO) data in the period from Jul.2001 to Oct.2008,were modeled and analyzed in this work.The global distribution and variation of these parameters with latitude were estimated and analyzed using the Empirical Orthogonal Function(EOF),which was introduced to reveal the possible relationship between the tropopause variations and global climate change.The tropopause height and temperature varied with latitude.The results obtained by using the Empirical Orthogonal Function analysis suggested a recent rise in tropopause height and decrease in tropopause temperature;and also partly supported the argument that the global rise in the tropopause is consistent with global climate change.These results also revealed that the tropopause height increased mainly in the Polar regions,particularly in the South Polar region,as well as the regions where human activity is relatively significant,and decreased in the areas that are sparsely populated or have less human activity,such as the tropic region and south hemisphere.This paper also confirms that the GPS/LEO RO data are more reliable and can be effectively used to analyze the tropopause physical parameters.
