This paper discusses theories and methods of climate change risk studies for the research expansion in China. Climate change risks consist of three basic components including sensitivity, exposure, and possibility. Un...This paper discusses theories and methods of climate change risk studies for the research expansion in China. Climate change risks consist of three basic components including sensitivity, exposure, and possibility. Uncertainty, future events, damages, and relativity are the major features of climate change risk. Climate change risk research includes two key steps: risk assessment and risk management, the former is the process, and the latter is the ultimate goal which is the basis for actions to address climate change. We present the main framework and methods for climate change risk research. A case study on China's floods risk is taken as an example of climate change risk study. Finally, we point out main aspects of climate change risk research, including ensemble-based probabilistic projection, quantitative risk assessment, risk zoning and mapping, and risk management.展开更多
In this paper, we conduct research on the cause and dynamics of seawater intrusion in the Laizhou bay. To consider modelling the Laizhou bay, we should then take the listed tools into consideration. In actual engineer...In this paper, we conduct research on the cause and dynamics of seawater intrusion in the Laizhou bay. To consider modelling the Laizhou bay, we should then take the listed tools into consideration. In actual engineering, wave is a complicated stochastic process. If the numerical value of wave model is a little too large, the wave attenuation should be considered sufficiently, such as wave refraction caused by terrain change, wave attenuation due to submarine friction, wave into the very shallow waters of the broken and small wind area. We integrate the current conition of the Laizhou bay and the further model the seawater intrusion steps. The uncertainty research of ground water solute migration is at present a ground water research area quite popular topic, but the seawater intrusion is the variable density class solute migration issue, applies the uncertainty analysis of seawater intrusion simulation also to have certain difficulty the existing research results. In the future, more simulation will be down to verify the effectiveness.展开更多
Supplementary annotations on special forms 1to 4, discussion on the general characteristics of K(t) and K(t, t), and analyses on two noticeable limits are presented in this part. It is demonstrated that strong and wea...Supplementary annotations on special forms 1to 4, discussion on the general characteristics of K(t) and K(t, t), and analyses on two noticeable limits are presented in this part. It is demonstrated that strong and weak parabolic transforms can be employed to change the standard form of a multi-variable indeterminate form into xmK type, hence to derive the standard formulae of the limit and the differential.展开更多
Geostationary(GEO) satellites form an indispensable component of the constellation of Beidou navigation system(BDS). The ephemerides, or predicted orbits of these GEO satellites(GEOs), are broadcast to positioning, na...Geostationary(GEO) satellites form an indispensable component of the constellation of Beidou navigation system(BDS). The ephemerides, or predicted orbits of these GEO satellites(GEOs), are broadcast to positioning, navigation, and timing users. User equivalent ranging error(UERE) based on broadcast message is better than 1.5 m(root formal errors: RMS) for GEO satellites. However, monitoring of UERE indicates that the orbital prediction precision is significantly degraded when the Sun is close to the Earth's equatorial plane(or near spring or autumn Equinox). Error source analysis shows that the complicated solar radiation pressure on satellite buses and the simple box-wing model maybe the major contributor to the deterioration of orbital precision. With the aid of BDS' two-way frequency and time transfer between the GEOs and Beidou time(BDT, that is maintained at the master control station), we propose a new orbit determination strategy, namely three-step approach of the multi-satellite precise orbit determination(MPOD). Pseudo-range(carrier phase) data are transformed to geometric range(biased geometric range) data without clock offsets; and reasonable empirical acceleration parameters are estimated along with orbital elements to account for the error in solar radiation pressure modeling. Experiments with Beidou data show that using the proposed approach, the GEOs' UERE when near the autumn Equinox of 2012 can be improved to 1.3 m from 2.5 m(RMS), and the probability of user equivalent range error(UERE)<2.0 m can be improved from 50% to above 85%.展开更多
This paper considers a new form of the Steiner tree problem that is more practical and reliable,which we call Reliable Steiner Tree(RST)problem.The authors give a detailed definition for this new problem and design bo...This paper considers a new form of the Steiner tree problem that is more practical and reliable,which we call Reliable Steiner Tree(RST)problem.The authors give a detailed definition for this new problem and design both an exact algorithm and an approximation algorithm for it.The definition is based on the reliability of full components instead of Steiner vertices.The task is thus to find the most reliable full components to make up an optimum reliable Steiner tree.The exact algorithm designed for this problem utilizes a dynamic programming frame.The approximation algorithm designed in this paper exploits a local search strategy that looks for the best full component according to a selection function at a time.展开更多
基金supported by National Science and Technology Support Program (No. 2012BAC19B10)Knowledge Innovation Project of the Chinese Academy of Sciences (No. KZCXZ-YW-QO3-01)
文摘This paper discusses theories and methods of climate change risk studies for the research expansion in China. Climate change risks consist of three basic components including sensitivity, exposure, and possibility. Uncertainty, future events, damages, and relativity are the major features of climate change risk. Climate change risk research includes two key steps: risk assessment and risk management, the former is the process, and the latter is the ultimate goal which is the basis for actions to address climate change. We present the main framework and methods for climate change risk research. A case study on China's floods risk is taken as an example of climate change risk study. Finally, we point out main aspects of climate change risk research, including ensemble-based probabilistic projection, quantitative risk assessment, risk zoning and mapping, and risk management.
文摘In this paper, we conduct research on the cause and dynamics of seawater intrusion in the Laizhou bay. To consider modelling the Laizhou bay, we should then take the listed tools into consideration. In actual engineering, wave is a complicated stochastic process. If the numerical value of wave model is a little too large, the wave attenuation should be considered sufficiently, such as wave refraction caused by terrain change, wave attenuation due to submarine friction, wave into the very shallow waters of the broken and small wind area. We integrate the current conition of the Laizhou bay and the further model the seawater intrusion steps. The uncertainty research of ground water solute migration is at present a ground water research area quite popular topic, but the seawater intrusion is the variable density class solute migration issue, applies the uncertainty analysis of seawater intrusion simulation also to have certain difficulty the existing research results. In the future, more simulation will be down to verify the effectiveness.
文摘Supplementary annotations on special forms 1to 4, discussion on the general characteristics of K(t) and K(t, t), and analyses on two noticeable limits are presented in this part. It is demonstrated that strong and weak parabolic transforms can be employed to change the standard form of a multi-variable indeterminate form into xmK type, hence to derive the standard formulae of the limit and the differential.
基金supported by the National Natural Science Foundation of China(Grant Nos.11033004,41204022 and 41204023)the Opening Project of Shanghai Key Laboratory of Space Navigation and Position Techniques(Grant Nos.12DZ2273300 and 13DZ2273300)Surveying and Mapping Basic Research Program of National Administration of Surveying,Mapping and Geoinformation(Grant No.2013-01-06)
文摘Geostationary(GEO) satellites form an indispensable component of the constellation of Beidou navigation system(BDS). The ephemerides, or predicted orbits of these GEO satellites(GEOs), are broadcast to positioning, navigation, and timing users. User equivalent ranging error(UERE) based on broadcast message is better than 1.5 m(root formal errors: RMS) for GEO satellites. However, monitoring of UERE indicates that the orbital prediction precision is significantly degraded when the Sun is close to the Earth's equatorial plane(or near spring or autumn Equinox). Error source analysis shows that the complicated solar radiation pressure on satellite buses and the simple box-wing model maybe the major contributor to the deterioration of orbital precision. With the aid of BDS' two-way frequency and time transfer between the GEOs and Beidou time(BDT, that is maintained at the master control station), we propose a new orbit determination strategy, namely three-step approach of the multi-satellite precise orbit determination(MPOD). Pseudo-range(carrier phase) data are transformed to geometric range(biased geometric range) data without clock offsets; and reasonable empirical acceleration parameters are estimated along with orbital elements to account for the error in solar radiation pressure modeling. Experiments with Beidou data show that using the proposed approach, the GEOs' UERE when near the autumn Equinox of 2012 can be improved to 1.3 m from 2.5 m(RMS), and the probability of user equivalent range error(UERE)<2.0 m can be improved from 50% to above 85%.
基金supported by National Natural Science Foundation of China under Grant Nos.71171189,71271204,11101420Knowledge Innovation Program of the Chinese Academy of Sciences under Grant No.KGCX2-RW-329
文摘This paper considers a new form of the Steiner tree problem that is more practical and reliable,which we call Reliable Steiner Tree(RST)problem.The authors give a detailed definition for this new problem and design both an exact algorithm and an approximation algorithm for it.The definition is based on the reliability of full components instead of Steiner vertices.The task is thus to find the most reliable full components to make up an optimum reliable Steiner tree.The exact algorithm designed for this problem utilizes a dynamic programming frame.The approximation algorithm designed in this paper exploits a local search strategy that looks for the best full component according to a selection function at a time.
