Extreme snowfall events over the Tibetan Plateau(TP)cause considerable damage to local society and natural ecosystems.In this study,the authors investigate the projected changes in such events over the TP and its surr...Extreme snowfall events over the Tibetan Plateau(TP)cause considerable damage to local society and natural ecosystems.In this study,the authors investigate the projected changes in such events over the TP and its surrounding areas based on an ensemble of a set of 21st century climate change projections using a regional climate model,RegCM4.The model is driven by five CMIP5 global climate models at a grid spacing of 25 km,under the RCP4.5 and RCP8.5 pathways.Four modified ETCCDI extreme indices-namely,SNOWTOT,S1mm,S10mm,and Sx5day-are employed to characterize the extreme snowfall events.RegCM4 generally reproduces the spatial distribution of the indices over the region,although with a tendency of overestimation.For the projected changes,a general decrease in SNOWTOT is found over most of the TP,with greater magnitude and better cross-simulation agreement over the eastern part.All the simulations project an overall decrease in S1mm,ranging from a 25%decrease in the west and to a 50%decrease in the east of the TP.Both S10mm and Sx5day are projected to decrease over the eastern part and increase over the central and western parts of the TP.Notably,S10mm shows a marked increase(more than double)with high cross-simulation agreement over the central TP.Significant increases in all four indices are found over the Tarim and Qaidam basins,and northwestern China north of the TP.The projected changes show topographic dependence over the TP in the latitudinal direction,and tend to decrease/increase in low-/high-altitude areas.展开更多
[Objective] This study was to provide basis for the scientific management of land use in Haihe River Basin (HRB) through the quantitative exploration of the land use conversion, changes of intensity and spatial dist...[Objective] This study was to provide basis for the scientific management of land use in Haihe River Basin (HRB) through the quantitative exploration of the land use conversion, changes of intensity and spatial distribution in this region. [Method] With the support of remote sensing technology and geographic information technology, the land use maps of the study area in 40 years (1970-2010) were in- terpreted and plotted. Four kinds of tupu, namely, land use change tupu, process tupu, arising tupu and evolution mode tupu were built through the spatial overlay of the land use maps to analyze the change rules of land use patterns. [Result] The conversion of arable land to construction land was the main characteristics of land use changes in HRB for the 40 years; the area of non-stable region accounted for 35% of the total, indicating that the land use changed remarkably, thus, it was nec- essary to strengthen the scientific land management in HRB; the new conversions to all land use patterns were all the lowest in 1980-1990, indicating that land use changed slowly during this period. [Conclusion] The results indicate that, compared with conventional transfer matrix method, geo-information tupu has obvious advantage in analyzing land use changes that it can demonstrate the spatial distribution of interest region, display the multi-dimensional spatial information.展开更多
One of the most important characteristics of culture is that it is subject to change. The theory of cultural patterns in intercultural communication is used to study the change of Chinese students' living pattern, co...One of the most important characteristics of culture is that it is subject to change. The theory of cultural patterns in intercultural communication is used to study the change of Chinese students' living pattern, communication pattern and thinking pattern because of globalization. The factors and reasons of both change and the unchanged are analyzed and summarized.展开更多
With the help of GIS tool of ARC/INFO, ARCVIEW and FRAGSTATS, the map of forest resource distribution of Heilongjiang Province was analyzed in 1896, 1949 and 1981. Using total area, mean patch size, patch density, coe...With the help of GIS tool of ARC/INFO, ARCVIEW and FRAGSTATS, the map of forest resource distribution of Heilongjiang Province was analyzed in 1896, 1949 and 1981. Using total area, mean patch size, patch density, coefficient of patch size variation, mean patch fractal dimension and mean shape index, we studied the change of forest landscape pattern and the change of each patch types in this region. As a result, the total area of forest landscape and mean patch size decreased sharply, the quantity and density of patches increased, the juxtaposition of patches weakened, the shape of patch tended to become regular, and the border of patch simplified. All these showed that the forest landscape of this area tended to fragment gradually, and the fragment of Korean pine forest is the severest. The diversity of whole forest landscape and the evenness of landscape types distribution reduced gradually. Human impact, instead of climate change and forest community succession, is the most important reason for such dramatic changes.展开更多
The Los Alamos Sea-Ice Model(CICE)is one of the most popular sea-ice models.All versions of it have been the main sea-ice module coupled to climate system models.Therefore,evaluating their simulation capability is an ...The Los Alamos Sea-Ice Model(CICE)is one of the most popular sea-ice models.All versions of it have been the main sea-ice module coupled to climate system models.Therefore,evaluating their simulation capability is an important step in developing climate system models.Compared with observations and previous versions(CICE4.0 and CICE5.0),the advantages of CICE6.0(the latest version)are analyzed in this paper.It is found that CICE6.0 has the minimum interannual errors,and the seasonal cycle it simulates is the most consistent with observations.CICE4.0 overestimates winter sea-ice and underestimates summer sea-ice severely.Meanwhile,the errors of CICE5.0 in winter are larger than for the other versions.The main attention is paid to the perennial ice and the seasonal ice.The spatial distribution of root-mean-square errors indicates that the simulated errors are distributed in the Atlantic sector and the outer Arctic.Both CICE4.0 and CICE5.0 underestimate the concentration of the perennial ice and overestimate that of the seasonal ice in these areas.Meanwhile,CICE6.0 solves this problem commendably.Moreover,the decadal trends it simulates are comparatively the best,especially in the central Arctic sea.The other versions underestimate the decadal trend of the perennial ice and overestimate that of the seasonal ice.In addition,an index used to objectively describe the difference in the spatial distribution between the simulation and observation shows that CICE6.0 produces the best simulated spatial distribution.展开更多
In this research, one-dimensional stratiform a novel dual-model system, cold cloud model (1DSC) coupled to Weather Research and Forecast (WRF) model (WRF-1DSC for short), was employed to investigate the effects ...In this research, one-dimensional stratiform a novel dual-model system, cold cloud model (1DSC) coupled to Weather Research and Forecast (WRF) model (WRF-1DSC for short), was employed to investigate the effects of cloud seeding by silver iodide (AgI) on rain enhancement. Driven by changing environmental conditions extracted from the WRF model, WRF-1DSC could be used to assess the cloud seeding effects quantitatively. The employment of WRF- 1DSC, in place of a one-dimen- sional two-moment cloud seeding model applied to a three-dimensional mesoscale cloud-resolving model, was found to result in massive reduction of computational resources. Numerical experiments with WRF-1DSC were conducted for a real stratiform precipitation event ob- served on 4-5 July 2004, in Northeast China. A good agreement between the observed and modeled cloud system ensured the ability of WRF-1DSC to simulate the observed precipitation process efficiently. Sensitivity tests were performed with different seeding times, locations, and amounts. Experimental results showed that the optimum seeding effect (defined as the percentage of rain enhancement or rain enhancement rate) could be achieved through proper seeding at locations of maximum cloud water content when the updraft was strong. The optimum seeding effect was found to increase by 5.61% when the cloud was seeded at 5.5 km above ground level around 2300 UTC 4 July 2004, with the maximum AgI mixing ratio (As) equaling 15 ng kg-1. On the other hand, for an overseeded cloud, a significant reduction occurred in the accumulated precipitation (-12.42%) as Xs reached 100 ng kg^-1. This study demonstrates the potential of WRF- 1DSC in determining the optimal AgI seeding strategy in practical operations of precipitation enhancement.展开更多
A robustness-tracking control scheme based on combining H_∞ robust control and sliding mode control is proposed for a direct drive AC permanent-magnet linear motor servo system to solve the conflict between tracking ...A robustness-tracking control scheme based on combining H_∞ robust control and sliding mode control is proposed for a direct drive AC permanent-magnet linear motor servo system to solve the conflict between tracking and robustness of the linear servo system. The sliding mode tracking controller is designed to ensure the system has a fast tracking characteristic to the command, and the H_∞ robustness controller suppresses the disturbances well within the close loop(including the load and the end effect force of linear motor etc.) and effectively minimizes the chattering of sliding mode control which influences the steady state performance of the system. Simulation results show that this control scheme enhances the track-command-ability and the robustness of the linear servo system, and in addition, it has a strong robustness to parameter variations and resistance disturbances.展开更多
The authors exploit the remarkable connection between the Chinese climate trends and the annular modes by partitioning the trends into components linearly congruent with and linearly independent of the annular modes. ...The authors exploit the remarkable connection between the Chinese climate trends and the annular modes by partitioning the trends into components linearly congruent with and linearly independent of the annular modes. Results show that the winter hemisphere annular mode has closer connection to Chinese climate than the summer one, e.g., the wetting JJA (June-July-August) rainfall trend along the Yangtze River valley and the associated temperature trends are significantly linearly congruent with the trend of the southern annular mode, while the JFM (January-February-March) climate trends are closely linked to the northern annular mode. The seasonal differences of a meridional wave-train-like chain across the equatorial Pacific associated with the annular modes are responsible for the seasonal-dependent connections to Chinese climate.展开更多
The production of elastase by Bacillus sp. EL31410 at various temperatures was investigated. In order to study the effect of temperature on elastase fermentation, different cultivation temperatures, ranging from 39 ℃...The production of elastase by Bacillus sp. EL31410 at various temperatures was investigated. In order to study the effect of temperature on elastase fermentation, different cultivation temperatures, ranging from 39 ℃ to 28 ℃, were evaluated in shake flask. The result indicated that 37 ℃ was best for cell growth at earlier stage; while maximum elastase activity was obtained when the cells were cultivated at 30 ℃. This result was verified by batch fermentation in 5-L bio-reactor under 37 ℃ and 30 ℃ temperature, respectively. The specific cell growth rate at 37 ℃ was higher than that at 30 ℃ during earlier stage of cultivation. The maximum value [5.5 U/(h-g DCW)] of elastase formation rate occurred at 24 h at 30 ℃ compared to 4.6 U/(h-g DCW) at 30 h at 37 ℃. Based on these results, two-stage temperature shift strategy and oscillatory temperature cultivation mode were evaluated in the next study. When compared to single temperature of 37 ℃ or 30 ℃, both two-stage temperature shift strategy and oscillatory temperature strategy improved biomass but did not yield the same result as expected for elastase production. The maximum biomass (both 8.6 g/L) was achieved at 30 h at 37 ℃, but at 42 h using two-stage temperature cultivation strategy. The highest elastase production (652 U/ml) was observed at 30 ℃ in batch process. It was concluded that cultivation at constant temperature of 30 ℃ was appropriate for elastase production by Bacillus sp. EL31410.展开更多
1 Introduction Major and profound changes have taken place in China over the past 30 years. An epidemic of cardiovascular diseases (CVD) in China is emerging as a result of lifestyle changes, urbanization, and the ...1 Introduction Major and profound changes have taken place in China over the past 30 years. An epidemic of cardiovascular diseases (CVD) in China is emerging as a result of lifestyle changes, urbanization, and the accelerated process of aging. The incidence of CVD is continuously increasing and will remain an upward trend in the next decade. Since 2005,展开更多
Driven by the global model,Beijing Climate Center Climate System Model version 1.1(BCC_CSM1.1),climate change over China in the 21st century is simulated by a regional climate model(RegCM4.0)under the new emission sce...Driven by the global model,Beijing Climate Center Climate System Model version 1.1(BCC_CSM1.1),climate change over China in the 21st century is simulated by a regional climate model(RegCM4.0)under the new emission scenarios of the Representative Concentration Pathways—RCP4.5 and RCP8.5.This is based on a period of transient simulations from 1950 to2099,with a grid spacing of 50 km.The present paper focuses on the annual mean temperature and precipitation in China over this period,with emphasis on their future changes.Validation of model performance reveals marked improvement of the RegCM4.0 model in reproducing present day temperature and precipitation relative to the driving BCC_CSM1.1 model.Significant warming is simulated by both BCC_CSM1.1 and RegCM4.0,however,spatial distribution and magnitude differ between the simulations.The high emission scenario RCP8.5 results in greater warming compared to RCP4.5.The two models project different precipitation changes,characterized by a general increase in the BCC_CSM1.1,and broader areas with decrease in the RegCM4.0 simulations.展开更多
The historical simulation of phase five of the Coupled Model Intercomparison Project (CMIP5) ex- periments performed by the Beijing Climate Center cli- mate system model (BCC_CSM1.1) is evaluated regard- ing the t...The historical simulation of phase five of the Coupled Model Intercomparison Project (CMIP5) ex- periments performed by the Beijing Climate Center cli- mate system model (BCC_CSM1.1) is evaluated regard- ing the time evolutions of the global and China mean sur- face air temperature (SAT) and surface climate change over China in recent decades. BCC CSM1.1 has better capability at reproducing the time evolutions of the global and China mean SAT than BCC_CSM1.0. By the year 2005, the BCC_CSM1.1 model simulates a warming am- plitude of approximately I℃ in China over the 1961- 1990 mean, which is consistent with observation. The distributions of the warming trend over China in the four seasons during 1958-2004 are basically reproduced by BCC CSM1.1, with the warmest occurring in winter. Al- though the cooling signal of Southwest China in spring is partly reproduced by BCC_CSM1.1, the cooling trend over central eastern China in summer is omitted by the model. For the precipitation change, BCC_CSM1.1 has good performance in spring, with drought in Southeast China. After removing the linear trend, the interannual correlation map between the model and the observation shows that the model has better capability at reproducing the summer SAT over China and spring precipitation over Southeast China.展开更多
The simplest normal form of resonant double Hopf bifurcation was studied based on Lie operator. The coefficients of the simplest normal forms of resonant double Hopf bifurcation and the nonlinear transformations in te...The simplest normal form of resonant double Hopf bifurcation was studied based on Lie operator. The coefficients of the simplest normal forms of resonant double Hopf bifurcation and the nonlinear transformations in terms of the original system coefficients were given explicitly. The nonlinear transformations were used for reducing the lower- and higher-order normal forms, and the rank of system matrix was used to determine the coefficient of normal form which could be reduced. These make the gained normal form simpler than the traditional one. A general program was compiled with Mathematica. This program can compute the simplest normal form of resonant double Hopf bifurcation and the non-resonant form up to the 7th order.展开更多
AIM: Real-time and rapid Identification of the malignant tissue can be performed during or before surgical operation. Here we aimed to detect in vivo and in situ colorectal cancer by using Fourier transform infrared (...AIM: Real-time and rapid Identification of the malignant tissue can be performed during or before surgical operation. Here we aimed to detect in vivo and in situ colorectal cancer by using Fourier transform infrared (FTIR) spectroscopy and fiber-optic technology. METHODS: A total of five patients with large intestine cancer were detected in vivo and in situ. Of them, three cases of colon cancer and one case of cecum cancer were detected intraoperatively and in vivo by using a FTIR spectrometer during surgical operation, and one case of rectum cancer was explored non-invasively and in vivo before the surgical operation. Normal and malignant colorectal tissues were detected in vivo and in situ using FTIR spectroscopy on the basis of fundamental studies. RESULTS: There were significant differences between FTIR spectra of normal and malignant colorectal tissues detected in vivo and in situ. Experimental results revealed that the spectral characteristics of normal and malignant tissues found in vivo and in situ were similar to those obtained from in vitro measurement in our previous fundamental research. CONCLUSION: FTIR fiber-optic attenuated total reflectance (ATR) spectroscopy can identify in situ and in vivo colorectal cancer. FTIR spectroscopie method with fiber optics is a non-invasive, rapid, accurate and in vivo cancer detection technique in clinical diagnosis.展开更多
Spatial distributions and seasonal variations of picoplankton (i.e. Synechococcus spp., Prochlorococcus spp., picoeukaryotes and heterotrophic bacteria) and viruses in the Changjiang estuary have been reported in the ...Spatial distributions and seasonal variations of picoplankton (i.e. Synechococcus spp., Prochlorococcus spp., picoeukaryotes and heterotrophic bacteria) and viruses in the Changjiang estuary have been reported in the past. However, short-term variations (e.g. at a tidal timescale) of these organisms and their regulating factors remain unclear. We determined the time-series of fluctuations of picoplankton and viruses with tide simultaneously in flow cytometry in the Changjiang estuary during a cruise in June 2006, in which a tidal model based rectangle equation was applied. The results indicate that high cell abundances of picoplankton and viruses occurred during flood tide and low cell abundances during ebb tide. The period of the surface cell abundance variations was about 13 h, suggesting the surface cell abundances in the Changjiang estuary were largely regulated by tide. However, cell abundances in middle and bottom waters varied in different periods due to influences of tidal induced physical forces such as resuspension and stratification. Therefore, tidal action is an important factor for the diel variations of picoplankton and viruses in the Changjiang estuary.展开更多
A quasi-global high-resolution HYbrid Coordinate Ocean Model (HYCOM) is used to investigate seasonal variations of water transports through the four main straits in the South China Sea. The results show that the annua...A quasi-global high-resolution HYbrid Coordinate Ocean Model (HYCOM) is used to investigate seasonal variations of water transports through the four main straits in the South China Sea. The results show that the annual transports through the four straits Luzon Strait, Taiwan Strait, Sunda Shelf and Mindoro Strait are -4.5, 2.3, 0.5 and 1.7 Sv (1 Sv=106 m3s-1), respectively. The Mindoro Strait has an important outflow that accounts for over one third of the total inflow through the Luzon Strait. Furthermore, it indicates that there are strong seasonal variations of water transport in the four straits. The water transport through the Luzon Strait (Taiwan Strait, Sunda Shelf, Mindoro Strait) has a maximum value of -7.6 Sv in December (3.1 Sv in July, 2.1S v in January, 4.5Sv in November), a minimum value of -2.1 Sv in June (1.5 Sv in October, -1.0 Sv in June, -0.2 Sv in May), respectively.展开更多
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences[grant number XDA2006040102]the National Natural Science Foundation of China[grant number 42175037].
文摘Extreme snowfall events over the Tibetan Plateau(TP)cause considerable damage to local society and natural ecosystems.In this study,the authors investigate the projected changes in such events over the TP and its surrounding areas based on an ensemble of a set of 21st century climate change projections using a regional climate model,RegCM4.The model is driven by five CMIP5 global climate models at a grid spacing of 25 km,under the RCP4.5 and RCP8.5 pathways.Four modified ETCCDI extreme indices-namely,SNOWTOT,S1mm,S10mm,and Sx5day-are employed to characterize the extreme snowfall events.RegCM4 generally reproduces the spatial distribution of the indices over the region,although with a tendency of overestimation.For the projected changes,a general decrease in SNOWTOT is found over most of the TP,with greater magnitude and better cross-simulation agreement over the eastern part.All the simulations project an overall decrease in S1mm,ranging from a 25%decrease in the west and to a 50%decrease in the east of the TP.Both S10mm and Sx5day are projected to decrease over the eastern part and increase over the central and western parts of the TP.Notably,S10mm shows a marked increase(more than double)with high cross-simulation agreement over the central TP.Significant increases in all four indices are found over the Tarim and Qaidam basins,and northwestern China north of the TP.The projected changes show topographic dependence over the TP in the latitudinal direction,and tend to decrease/increase in low-/high-altitude areas.
基金Supported by the Key Technology R&D Program of Hebei Province (10277105D)the Funds of the Chinese Academy of Sciences for Key Topics in Innovation Engineering(KSCX-EW-J-5)~~
文摘[Objective] This study was to provide basis for the scientific management of land use in Haihe River Basin (HRB) through the quantitative exploration of the land use conversion, changes of intensity and spatial distribution in this region. [Method] With the support of remote sensing technology and geographic information technology, the land use maps of the study area in 40 years (1970-2010) were in- terpreted and plotted. Four kinds of tupu, namely, land use change tupu, process tupu, arising tupu and evolution mode tupu were built through the spatial overlay of the land use maps to analyze the change rules of land use patterns. [Result] The conversion of arable land to construction land was the main characteristics of land use changes in HRB for the 40 years; the area of non-stable region accounted for 35% of the total, indicating that the land use changed remarkably, thus, it was nec- essary to strengthen the scientific land management in HRB; the new conversions to all land use patterns were all the lowest in 1980-1990, indicating that land use changed slowly during this period. [Conclusion] The results indicate that, compared with conventional transfer matrix method, geo-information tupu has obvious advantage in analyzing land use changes that it can demonstrate the spatial distribution of interest region, display the multi-dimensional spatial information.
文摘One of the most important characteristics of culture is that it is subject to change. The theory of cultural patterns in intercultural communication is used to study the change of Chinese students' living pattern, communication pattern and thinking pattern because of globalization. The factors and reasons of both change and the unchanged are analyzed and summarized.
基金The research is supported by Study on the interaction of global change and terrestrial ecosystem in eastern China - 39899370 and the Northeast Forestry University research fund.
文摘With the help of GIS tool of ARC/INFO, ARCVIEW and FRAGSTATS, the map of forest resource distribution of Heilongjiang Province was analyzed in 1896, 1949 and 1981. Using total area, mean patch size, patch density, coefficient of patch size variation, mean patch fractal dimension and mean shape index, we studied the change of forest landscape pattern and the change of each patch types in this region. As a result, the total area of forest landscape and mean patch size decreased sharply, the quantity and density of patches increased, the juxtaposition of patches weakened, the shape of patch tended to become regular, and the border of patch simplified. All these showed that the forest landscape of this area tended to fragment gradually, and the fragment of Korean pine forest is the severest. The diversity of whole forest landscape and the evenness of landscape types distribution reduced gradually. Human impact, instead of climate change and forest community succession, is the most important reason for such dramatic changes.
基金This research is supported jointly by the National Key R&D Program of China[grant numbers 2016YFA0602100 and 2018YFC1407104]the china Special Fund for Meteorological Research in the Public Interest[grant number GYHY201506011]the National Natural Science Foundation of China[grant number 41975134].
文摘The Los Alamos Sea-Ice Model(CICE)is one of the most popular sea-ice models.All versions of it have been the main sea-ice module coupled to climate system models.Therefore,evaluating their simulation capability is an important step in developing climate system models.Compared with observations and previous versions(CICE4.0 and CICE5.0),the advantages of CICE6.0(the latest version)are analyzed in this paper.It is found that CICE6.0 has the minimum interannual errors,and the seasonal cycle it simulates is the most consistent with observations.CICE4.0 overestimates winter sea-ice and underestimates summer sea-ice severely.Meanwhile,the errors of CICE5.0 in winter are larger than for the other versions.The main attention is paid to the perennial ice and the seasonal ice.The spatial distribution of root-mean-square errors indicates that the simulated errors are distributed in the Atlantic sector and the outer Arctic.Both CICE4.0 and CICE5.0 underestimate the concentration of the perennial ice and overestimate that of the seasonal ice in these areas.Meanwhile,CICE6.0 solves this problem commendably.Moreover,the decadal trends it simulates are comparatively the best,especially in the central Arctic sea.The other versions underestimate the decadal trend of the perennial ice and overestimate that of the seasonal ice.In addition,an index used to objectively describe the difference in the spatial distribution between the simulation and observation shows that CICE6.0 produces the best simulated spatial distribution.
基金supported by the Knowledge Innovation Program of Chinese Academy of Sciences (Grant No. KZCX2-EW-203)the National Basic Research Program of China (Grant No.2013CB430105)the National Department Public Benefit Research Foundation (Grant No.GYHY201006031)
文摘In this research, one-dimensional stratiform a novel dual-model system, cold cloud model (1DSC) coupled to Weather Research and Forecast (WRF) model (WRF-1DSC for short), was employed to investigate the effects of cloud seeding by silver iodide (AgI) on rain enhancement. Driven by changing environmental conditions extracted from the WRF model, WRF-1DSC could be used to assess the cloud seeding effects quantitatively. The employment of WRF- 1DSC, in place of a one-dimen- sional two-moment cloud seeding model applied to a three-dimensional mesoscale cloud-resolving model, was found to result in massive reduction of computational resources. Numerical experiments with WRF-1DSC were conducted for a real stratiform precipitation event ob- served on 4-5 July 2004, in Northeast China. A good agreement between the observed and modeled cloud system ensured the ability of WRF-1DSC to simulate the observed precipitation process efficiently. Sensitivity tests were performed with different seeding times, locations, and amounts. Experimental results showed that the optimum seeding effect (defined as the percentage of rain enhancement or rain enhancement rate) could be achieved through proper seeding at locations of maximum cloud water content when the updraft was strong. The optimum seeding effect was found to increase by 5.61% when the cloud was seeded at 5.5 km above ground level around 2300 UTC 4 July 2004, with the maximum AgI mixing ratio (As) equaling 15 ng kg-1. On the other hand, for an overseeded cloud, a significant reduction occurred in the accumulated precipitation (-12.42%) as Xs reached 100 ng kg^-1. This study demonstrates the potential of WRF- 1DSC in determining the optimal AgI seeding strategy in practical operations of precipitation enhancement.
文摘A robustness-tracking control scheme based on combining H_∞ robust control and sliding mode control is proposed for a direct drive AC permanent-magnet linear motor servo system to solve the conflict between tracking and robustness of the linear servo system. The sliding mode tracking controller is designed to ensure the system has a fast tracking characteristic to the command, and the H_∞ robustness controller suppresses the disturbances well within the close loop(including the load and the end effect force of linear motor etc.) and effectively minimizes the chattering of sliding mode control which influences the steady state performance of the system. Simulation results show that this control scheme enhances the track-command-ability and the robustness of the linear servo system, and in addition, it has a strong robustness to parameter variations and resistance disturbances.
基金supported by the Major State Basic Research Development Program of China (973 Program) under grant No. 2005CB321703the National Natural Science Foundation of China under Grant Nos. 40523001, 40221503, and 40625014the China Meteorological Administration under Grant No. GYHY200706010
文摘The authors exploit the remarkable connection between the Chinese climate trends and the annular modes by partitioning the trends into components linearly congruent with and linearly independent of the annular modes. Results show that the winter hemisphere annular mode has closer connection to Chinese climate than the summer one, e.g., the wetting JJA (June-July-August) rainfall trend along the Yangtze River valley and the associated temperature trends are significantly linearly congruent with the trend of the southern annular mode, while the JFM (January-February-March) climate trends are closely linked to the northern annular mode. The seasonal differences of a meridional wave-train-like chain across the equatorial Pacific associated with the annular modes are responsible for the seasonal-dependent connections to Chinese climate.
文摘The production of elastase by Bacillus sp. EL31410 at various temperatures was investigated. In order to study the effect of temperature on elastase fermentation, different cultivation temperatures, ranging from 39 ℃ to 28 ℃, were evaluated in shake flask. The result indicated that 37 ℃ was best for cell growth at earlier stage; while maximum elastase activity was obtained when the cells were cultivated at 30 ℃. This result was verified by batch fermentation in 5-L bio-reactor under 37 ℃ and 30 ℃ temperature, respectively. The specific cell growth rate at 37 ℃ was higher than that at 30 ℃ during earlier stage of cultivation. The maximum value [5.5 U/(h-g DCW)] of elastase formation rate occurred at 24 h at 30 ℃ compared to 4.6 U/(h-g DCW) at 30 h at 37 ℃. Based on these results, two-stage temperature shift strategy and oscillatory temperature cultivation mode were evaluated in the next study. When compared to single temperature of 37 ℃ or 30 ℃, both two-stage temperature shift strategy and oscillatory temperature strategy improved biomass but did not yield the same result as expected for elastase production. The maximum biomass (both 8.6 g/L) was achieved at 30 h at 37 ℃, but at 42 h using two-stage temperature cultivation strategy. The highest elastase production (652 U/ml) was observed at 30 ℃ in batch process. It was concluded that cultivation at constant temperature of 30 ℃ was appropriate for elastase production by Bacillus sp. EL31410.
文摘1 Introduction Major and profound changes have taken place in China over the past 30 years. An epidemic of cardiovascular diseases (CVD) in China is emerging as a result of lifestyle changes, urbanization, and the accelerated process of aging. The incidence of CVD is continuously increasing and will remain an upward trend in the next decade. Since 2005,
基金supported by the National Basic Research Program of China (Grant No. 2010CB 950903)the China-UK-Swiss Adapting to Climate Change in China Project (ACCC)-Climate Science
文摘Driven by the global model,Beijing Climate Center Climate System Model version 1.1(BCC_CSM1.1),climate change over China in the 21st century is simulated by a regional climate model(RegCM4.0)under the new emission scenarios of the Representative Concentration Pathways—RCP4.5 and RCP8.5.This is based on a period of transient simulations from 1950 to2099,with a grid spacing of 50 km.The present paper focuses on the annual mean temperature and precipitation in China over this period,with emphasis on their future changes.Validation of model performance reveals marked improvement of the RegCM4.0 model in reproducing present day temperature and precipitation relative to the driving BCC_CSM1.1 model.Significant warming is simulated by both BCC_CSM1.1 and RegCM4.0,however,spatial distribution and magnitude differ between the simulations.The high emission scenario RCP8.5 results in greater warming compared to RCP4.5.The two models project different precipitation changes,characterized by a general increase in the BCC_CSM1.1,and broader areas with decrease in the RegCM4.0 simulations.
基金supported by the National Basic Research Program of China (973 Program,2010CB951903)the National Natural Science Foundation of China (41105054)the China Meteorological Administration (GYHY200706010)
文摘The historical simulation of phase five of the Coupled Model Intercomparison Project (CMIP5) ex- periments performed by the Beijing Climate Center cli- mate system model (BCC_CSM1.1) is evaluated regard- ing the time evolutions of the global and China mean sur- face air temperature (SAT) and surface climate change over China in recent decades. BCC CSM1.1 has better capability at reproducing the time evolutions of the global and China mean SAT than BCC_CSM1.0. By the year 2005, the BCC_CSM1.1 model simulates a warming am- plitude of approximately I℃ in China over the 1961- 1990 mean, which is consistent with observation. The distributions of the warming trend over China in the four seasons during 1958-2004 are basically reproduced by BCC CSM1.1, with the warmest occurring in winter. Al- though the cooling signal of Southwest China in spring is partly reproduced by BCC_CSM1.1, the cooling trend over central eastern China in summer is omitted by the model. For the precipitation change, BCC_CSM1.1 has good performance in spring, with drought in Southeast China. After removing the linear trend, the interannual correlation map between the model and the observation shows that the model has better capability at reproducing the summer SAT over China and spring precipitation over Southeast China.
基金Supported by National Natural Science Foundation of China(No. 10372068).
文摘The simplest normal form of resonant double Hopf bifurcation was studied based on Lie operator. The coefficients of the simplest normal forms of resonant double Hopf bifurcation and the nonlinear transformations in terms of the original system coefficients were given explicitly. The nonlinear transformations were used for reducing the lower- and higher-order normal forms, and the rank of system matrix was used to determine the coefficient of normal form which could be reduced. These make the gained normal form simpler than the traditional one. A general program was compiled with Mathematica. This program can compute the simplest normal form of resonant double Hopf bifurcation and the non-resonant form up to the 7th order.
基金Supported by the National Natural Science Foundation of China, No. 30371604 State Key Project of China, No. 2002CCA01900
文摘AIM: Real-time and rapid Identification of the malignant tissue can be performed during or before surgical operation. Here we aimed to detect in vivo and in situ colorectal cancer by using Fourier transform infrared (FTIR) spectroscopy and fiber-optic technology. METHODS: A total of five patients with large intestine cancer were detected in vivo and in situ. Of them, three cases of colon cancer and one case of cecum cancer were detected intraoperatively and in vivo by using a FTIR spectrometer during surgical operation, and one case of rectum cancer was explored non-invasively and in vivo before the surgical operation. Normal and malignant colorectal tissues were detected in vivo and in situ using FTIR spectroscopy on the basis of fundamental studies. RESULTS: There were significant differences between FTIR spectra of normal and malignant colorectal tissues detected in vivo and in situ. Experimental results revealed that the spectral characteristics of normal and malignant tissues found in vivo and in situ were similar to those obtained from in vitro measurement in our previous fundamental research. CONCLUSION: FTIR fiber-optic attenuated total reflectance (ATR) spectroscopy can identify in situ and in vivo colorectal cancer. FTIR spectroscopie method with fiber optics is a non-invasive, rapid, accurate and in vivo cancer detection technique in clinical diagnosis.
基金Supported by the National Basic Research Program of China (973 Program) (Nos. 2002CB412405, 2004CB720505)a fund to the Innovative Research Team, the Ministry of Education of China (No.IRT0427)+1 种基金the PhD Program Scholarship Fund of ECNU 2007the Special Research Fund for the National Non-profit Institutes (East China Sea Fisheries Research Institutes) (No. 2008M13)
文摘Spatial distributions and seasonal variations of picoplankton (i.e. Synechococcus spp., Prochlorococcus spp., picoeukaryotes and heterotrophic bacteria) and viruses in the Changjiang estuary have been reported in the past. However, short-term variations (e.g. at a tidal timescale) of these organisms and their regulating factors remain unclear. We determined the time-series of fluctuations of picoplankton and viruses with tide simultaneously in flow cytometry in the Changjiang estuary during a cruise in June 2006, in which a tidal model based rectangle equation was applied. The results indicate that high cell abundances of picoplankton and viruses occurred during flood tide and low cell abundances during ebb tide. The period of the surface cell abundance variations was about 13 h, suggesting the surface cell abundances in the Changjiang estuary were largely regulated by tide. However, cell abundances in middle and bottom waters varied in different periods due to influences of tidal induced physical forces such as resuspension and stratification. Therefore, tidal action is an important factor for the diel variations of picoplankton and viruses in the Changjiang estuary.
基金Supported by National Natural Science Foundation of China (No. 40806012, 40876013)Open Fund of the Key Laboratory of Ocean Circulation and Waves, Chinese Academy of Sciences (No. KLOCAW0803)Scientific Research Foundation for talent, Guangdong Ocean University (No. E06118)
文摘A quasi-global high-resolution HYbrid Coordinate Ocean Model (HYCOM) is used to investigate seasonal variations of water transports through the four main straits in the South China Sea. The results show that the annual transports through the four straits Luzon Strait, Taiwan Strait, Sunda Shelf and Mindoro Strait are -4.5, 2.3, 0.5 and 1.7 Sv (1 Sv=106 m3s-1), respectively. The Mindoro Strait has an important outflow that accounts for over one third of the total inflow through the Luzon Strait. Furthermore, it indicates that there are strong seasonal variations of water transport in the four straits. The water transport through the Luzon Strait (Taiwan Strait, Sunda Shelf, Mindoro Strait) has a maximum value of -7.6 Sv in December (3.1 Sv in July, 2.1S v in January, 4.5Sv in November), a minimum value of -2.1 Sv in June (1.5 Sv in October, -1.0 Sv in June, -0.2 Sv in May), respectively.