We investigate the statistical nature of holographic gas, which may represent the quasi-particle excitations of a strongly correlated gravitational system. We find that the holographic entropy can be obtained by modif...We investigate the statistical nature of holographic gas, which may represent the quasi-particle excitations of a strongly correlated gravitational system. We find that the holographic entropy can be obtained by modifying degeneracy. We calculate thermodynamical quantities and investigate stability of the holographic gas. When applying to cosmology, we find that the holographic gas behaves as holographic dark energy, and the parameter c in holographic dark energy can be calculated from our model. Our model of holographic gas generally predicts c 〈 1, implying that the fate of our universe is phantom-like.展开更多
The total quantum statistical entropy of Reissner-Nordstrom black holes inDirac field case is evaluated in this article. The space-time of the black holes is divided intothree regions: region 1 (r 】 r_o), region 2 (r...The total quantum statistical entropy of Reissner-Nordstrom black holes inDirac field case is evaluated in this article. The space-time of the black holes is divided intothree regions: region 1 (r 】 r_o), region 2 (r_o 】 r 】 r_i), and region 3 (r_i 】 r 】 0), where r_ois the radius of the outer event horizon, and Ti is the radius of the inner event horizon. The totalquantum statistical entropy of Reissner-Nordstrom black holes is S = S_1 + S_2 + S_3, where S_i (i= 1,2,3) is the entropy, contributed by regions 1,2,3. The detailed calculation shows that S_2 isneglectfully small. S_1 = w_t(π~2/45)k_b(A_o/ε~2β~3), S_3 = -w_t(π~2/45)k_b(A_i/ε~2β~3), whereA_o and A_i are, respectively, the areas of the outer and inner event horizons, w_t = 2~s[1 -2~(-(s+1))], s = d/2, d is the space-time dimension, here d = 4, s = 2. As r_i approaches r_o in theextreme case the total quantum statistical entropy of Reissner-Nordstrom black holes approacheszero.展开更多
A three-dimensional positioning method for global positioning system(GPS)receivers based on three satellites was proposed.In the method,the measurement equation used for positioning calculation was expanded by means o...A three-dimensional positioning method for global positioning system(GPS)receivers based on three satellites was proposed.In the method,the measurement equation used for positioning calculation was expanded by means of two measures.In this case,the measurement equation could be solved,and the function of positioning calculation could be performed.The detailed steps of the method and how to evaluate the positioning precision of the method were given,respectively.The positioning performance of the method was demonstrated through some experiments.It is shown that the method can provide the three-dimensional positioning information under the condition that there are only three useful satellites.展开更多
This paper describes a geographic information system(GIS)-based method for observing changes in topography caused by the initiation, transport, and deposition of debris flows using highresolution light detection and r...This paper describes a geographic information system(GIS)-based method for observing changes in topography caused by the initiation, transport, and deposition of debris flows using highresolution light detection and ranging(LiDAR) digital elevation models(DEMs) obtained before and after the debris flow events. The paper also describes a method for estimating the volume of debris flows using the differences between the LiDAR DEMs. The relative and absolute positioning accuracies of the LiDAR DEMs were evaluated using a real-time precise global navigation satellite system(GNSS) positioning method. In addition, longitudinal and cross-sectional profiles of the study area were constructed to determine the topographic changes caused by the debris flows. The volume of the debris flows was estimated based on the difference between the LiDAR DEMs. The accuracies of the relative and absolute positioning of the two LiDAR DEMs were determined to be ±10 cm and ±11 cm RMSE, respectively, which demonstrates the efficiency of the method for determining topographic changes at an scale equivalent to that of field investigations. Based on the topographic changes, the volume of the debris flows in the study area was estimated to be 3747 m3, which is comparable with the volume estimated based on the data from field investigations.展开更多
The truncation error and propagation error are analyzed for velocity determination through differential GPS carrier phase observations,and an approach for the choice of the best number of points for the central differ...The truncation error and propagation error are analyzed for velocity determination through differential GPS carrier phase observations,and an approach for the choice of the best number of points for the central difference method is developed.In order to overcome the disadvantages of existing GPS velocity determination methods,a new velocity determination algorithm is presented,based on combining carrier phase and Doppler observations.The basic idea is that two types of observation are combined by adding their normal equations,and their weights are evaluated by strict Helmet variance-components estimation.In order to control the influence of outliers,a bifactor equivalent weights strategy is adopted.To validate this method,GPS data of the airborne gravimetry campaign MEXAGE2001 is tested.The results show that the precision and reliability of velocity determination are obviously improved by using the proposed method.展开更多
基金supported by National Natural Science Foundation of China under Grant No. 10525050a "973" Project under Grant No. 2007CB815401
文摘We investigate the statistical nature of holographic gas, which may represent the quasi-particle excitations of a strongly correlated gravitational system. We find that the holographic entropy can be obtained by modifying degeneracy. We calculate thermodynamical quantities and investigate stability of the holographic gas. When applying to cosmology, we find that the holographic gas behaves as holographic dark energy, and the parameter c in holographic dark energy can be calculated from our model. Our model of holographic gas generally predicts c 〈 1, implying that the fate of our universe is phantom-like.
文摘The total quantum statistical entropy of Reissner-Nordstrom black holes inDirac field case is evaluated in this article. The space-time of the black holes is divided intothree regions: region 1 (r 】 r_o), region 2 (r_o 】 r 】 r_i), and region 3 (r_i 】 r 】 0), where r_ois the radius of the outer event horizon, and Ti is the radius of the inner event horizon. The totalquantum statistical entropy of Reissner-Nordstrom black holes is S = S_1 + S_2 + S_3, where S_i (i= 1,2,3) is the entropy, contributed by regions 1,2,3. The detailed calculation shows that S_2 isneglectfully small. S_1 = w_t(π~2/45)k_b(A_o/ε~2β~3), S_3 = -w_t(π~2/45)k_b(A_i/ε~2β~3), whereA_o and A_i are, respectively, the areas of the outer and inner event horizons, w_t = 2~s[1 -2~(-(s+1))], s = d/2, d is the space-time dimension, here d = 4, s = 2. As r_i approaches r_o in theextreme case the total quantum statistical entropy of Reissner-Nordstrom black holes approacheszero.
基金Project (ZYGX2010J119)supported by the Fundamental Research Funds for the Central Universities of China
文摘A three-dimensional positioning method for global positioning system(GPS)receivers based on three satellites was proposed.In the method,the measurement equation used for positioning calculation was expanded by means of two measures.In this case,the measurement equation could be solved,and the function of positioning calculation could be performed.The detailed steps of the method and how to evaluate the positioning precision of the method were given,respectively.The positioning performance of the method was demonstrated through some experiments.It is shown that the method can provide the three-dimensional positioning information under the condition that there are only three useful satellites.
基金supported by the Public Welfare & Safety Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT & Future Planning (Grant No. 2012M3A2A1050979)
文摘This paper describes a geographic information system(GIS)-based method for observing changes in topography caused by the initiation, transport, and deposition of debris flows using highresolution light detection and ranging(LiDAR) digital elevation models(DEMs) obtained before and after the debris flow events. The paper also describes a method for estimating the volume of debris flows using the differences between the LiDAR DEMs. The relative and absolute positioning accuracies of the LiDAR DEMs were evaluated using a real-time precise global navigation satellite system(GNSS) positioning method. In addition, longitudinal and cross-sectional profiles of the study area were constructed to determine the topographic changes caused by the debris flows. The volume of the debris flows was estimated based on the difference between the LiDAR DEMs. The accuracies of the relative and absolute positioning of the two LiDAR DEMs were determined to be ±10 cm and ±11 cm RMSE, respectively, which demonstrates the efficiency of the method for determining topographic changes at an scale equivalent to that of field investigations. Based on the topographic changes, the volume of the debris flows in the study area was estimated to be 3747 m3, which is comparable with the volume estimated based on the data from field investigations.
基金supported by the National High Technology Research and Development of China (Grant No.2006AA12Z22)the National Natural Science Foundation of China (Grant No.40604003)+1 种基金the Foundation for Author of National Excellent Doctoral Dissertation of China (Grant No.2007B51)the China Postdoctoral Science Foundation (Grant No.20080430148,2009020444)
文摘The truncation error and propagation error are analyzed for velocity determination through differential GPS carrier phase observations,and an approach for the choice of the best number of points for the central difference method is developed.In order to overcome the disadvantages of existing GPS velocity determination methods,a new velocity determination algorithm is presented,based on combining carrier phase and Doppler observations.The basic idea is that two types of observation are combined by adding their normal equations,and their weights are evaluated by strict Helmet variance-components estimation.In order to control the influence of outliers,a bifactor equivalent weights strategy is adopted.To validate this method,GPS data of the airborne gravimetry campaign MEXAGE2001 is tested.The results show that the precision and reliability of velocity determination are obviously improved by using the proposed method.