Proper fixture design is crucial to obtain the better product quality according to the design specification during the workpiece fabrication. Locator layout planning is one of the most important tasks in the fixture ...Proper fixture design is crucial to obtain the better product quality according to the design specification during the workpiece fabrication. Locator layout planning is one of the most important tasks in the fixture design process. However, the design of a fixture relies heavily on the designerts expertise and experience up to now. Therefore, a new approach to loeator layout determination for workpieces with arbitrary complex surfaces is pro- posed for the first time. Firstly, based on the fuzzy judgment method, the proper locating reference and locator - numbers are determined with consideration of surface type, surface area and position tolerance. Secondly, the lo- cator positions are optimized by genetic algorithm(GA). Finally, a typical example shows that the approach is su- perior to the experiential method and can improve positioning accuracy effectively.展开更多
This paper discusses some issues on human reliability model of time dependent human behavior. Some results of the crew reliability experiment on Tsinghua training simulator in China are given, Meanwhile, a case of ca...This paper discusses some issues on human reliability model of time dependent human behavior. Some results of the crew reliability experiment on Tsinghua training simulator in China are given, Meanwhile, a case of calculation for human error probability during anticipated transient without scram (ATWS) based on the data drew from the recent experiment is offered.展开更多
In this letter,the sensitivity of an uplink Multi-Tone Code-Division Multiple Access (MT-CDMA) system to the Carrier Frequency Offset (CFO) is investigated. The analytical expression for the Bit Error Rate (BER) of up...In this letter,the sensitivity of an uplink Multi-Tone Code-Division Multiple Access (MT-CDMA) system to the Carrier Frequency Offset (CFO) is investigated. The analytical expression for the Bit Error Rate (BER) of uplink MT-CDMA in the presence of CFO is derived in a multipath Rayleigh fading channel which is verified through simulations. Both Maximal Ratio Combining (MRC) and Equal Gain Combining (EGC) are considered in combining multipath signals in the analysis. It is found that the BER performance can be improved with the number of multipath increasing in the presence of CFO.展开更多
We present the application of Support Vector Machine (SVM) for the prediction of blast induced ground vibration by taking into consideration of maximum charge per delay and distance between blast face to monitoring po...We present the application of Support Vector Machine (SVM) for the prediction of blast induced ground vibration by taking into consideration of maximum charge per delay and distance between blast face to monitoring point. To investigate the suitability of this approach, the predictions by SVM have been compared with conventional predictor equations. Blast vibration study was carried out at Magnesite mine of Pithoragarh, India. Total 170 blast vibrations data sets were recorded at different strate-gic and vulnerable locations in and around to mine. Out of 170 data sets, 150 were used for the training of the SVM network as well as to determine site constants of different conventional predictor equations, whereas, 20 new randomly selected data sets were used to compare the prediction capability of SVM network with conventional predictor equations. Results were compared based on Co-efficient of Determination (CoD) and Mean Absolute Error (MAE) between monitored and predicted values of Peak Particle Veloc-ity (PPV). It was found that SVM gives closer values of predicted PPV as compared to conventional predictor equations. The coef-ficient of determination between measured and predicted PPV by SVM was 0.955, whereas it was 0.262, 0.163, 0.337 and 0.232 by USBM, Langefors-Kihlstrom, Ambraseys-Hendron and Bureau of Indian Standard equations, respectively. The MAE for PPV was 11.13 by SVM, whereas it was 0.973, 1.088, 0.939 and 1.292 by USBM, Langefors-Kihlstrom, Ambraseys-Hendron and Bureau of Indian Standard equations respectively.展开更多
Using lAP AGCM simulation results for the period 1961-2005, summer hot days in China were calculated and then compared with observations. Generally, the spatial pattern of hot days is reasonably reproduced, with more ...Using lAP AGCM simulation results for the period 1961-2005, summer hot days in China were calculated and then compared with observations. Generally, the spatial pattern of hot days is reasonably reproduced, with more hot days found in northern China, the Yangtze and Huaihe River basin, the Chuan-Yu region, and southern Xinjiang. However, the model tends to overestimate the number of hot days in the above-mentioned regions, particularly in the Yangtze and Huaihe River basin where the simulated summer-mean hot days is 13 days more than observed when averaged over the whole region, and the maximum overestimation of hot days can reach 23 days in the region. Analysis of the probability distribution of daily maximum temperature (Trnax) suggests that the warm bias in the model-simulated Tmax contributes largely to the overestimation of hot days in the model. Furthermore, the discrepancy in the simulated variance of the Tmax distribution also plays a non- negligible role in the overestimation of hot days. Indeed, the latter can even account for 22% of the total bias of simulated hot days in August in the Yangtze and Huaihe River basin. The quantification of model bias from the mean value and variability can provide more information for further model improvement.展开更多
Accompanying the arrival of new technological and network ear, SACs (self-access centers) become the most widely adopted mode spreading in China with a large quantity of universities joining to follow the fashion. B...Accompanying the arrival of new technological and network ear, SACs (self-access centers) become the most widely adopted mode spreading in China with a large quantity of universities joining to follow the fashion. But whether the SACs in China can fully fulfill the purpose, to what extend can learners gain benefits to develop autonomy, and what are the possible ways for improvement are quite necessary to investigate since there starts to emerge various problems during the implementation of SACs. This paper aims to analyze the prevalent establishment of SACs in China in order to find out the reasons for prevalence, the current implementing mode, the degree of effectiveness on developing learner autonomy, especially potential problems and causes, and finally put forward some suggestions pedagogical implications for improving.展开更多
The effects of the mixing of wave transport flux residual(Bvl) on the upper ocean is studied through carrying out the control run(CR) and a series of sensitive runs(SR) with ROMS model.In this study,the important role...The effects of the mixing of wave transport flux residual(Bvl) on the upper ocean is studied through carrying out the control run(CR) and a series of sensitive runs(SR) with ROMS model.In this study,the important role of Bvl is revealed by comparing the ocean temperature,statistical analysis of errors and evaluating the mixed layer depth.It is shown that the overestimated SST is improved effectively when the wave-induced mixing is incorporated to the vertical mixing scheme.As can be seen from the vertical structure of temperature 28℃ isotherm changes from 20 min CR to 35 m in SR3,which is more close to the observation.Statistic analysis shows that the root-mean-square errors of the temperature in 10 m are reduced and the correlation between model results and observation data are increased after considering the effect of Bvl.The numerical results of the ocean temperature show improvement in summer and in tropical zones in winter,especially in the strong current regions in summer.In August the mixed layer depth(MLD) which is defined as the depth that the temperature has changed 0.5℃ from the reference depth of 10 m is further analyzed.The simulation results have a close relationship with undetermined coefficient of Bvl,sensitivity studies show that a coefficient about 0.1 is reasonable value in the model.展开更多
This study was conducted to evaluate the performance of the four stem taper models on Camellia japonica in Jeju Island, Korea using fit statistics and lack-of-fit statistics. The five statistical criteria that were us...This study was conducted to evaluate the performance of the four stem taper models on Camellia japonica in Jeju Island, Korea using fit statistics and lack-of-fit statistics. The five statistical criteria that were used in this study were standard error of estimate(SEE), mean bias( E), absolute mean difference(AMD), coefficient of determination(R2), and root mean square error(RMSE). Results showed that the Kozak model 02 stem taper had the best performance in all fit statistics(SEE: 3.4708, E : 0.0040 cm, AMD : 0.9060 cm, R2 : 0.9870, and RMSE : 1.2545). On the other hand, Max and Burkhart stem taper model had the poorest performance in each statistical criterion(SEE: 4.2121, E : 0.2520 cm, AMD : 1.1300 cm, R2 : 0.9805, and RMSE: 1.5317). For the lack-of-fit statistics, the Kozak model 02 also provided the best performance having the best AMD in most of the relative height classes for diameter outside bark prediction and in most of the DBH classes for total volume prediction while Max and Burkhart had the poorest performance. These stem taper equations could help forest managers to better estimate the diameter outside bark at any given height, merchantable stem volumes and total stem volumes of the standing trees of Camellia japonica in the forests of Jeju Island, Korea.展开更多
The heat parameters, the thermoanemometric flow-meter (TAF) errors and the experimental characteristics have been defined. The results of experiments were conducted with the help of physically-informational models a...The heat parameters, the thermoanemometric flow-meter (TAF) errors and the experimental characteristics have been defined. The results of experiments were conducted with the help of physically-informational models allowing to realize all major thermal methods and their inherent informative options. The metrological evaluation was made and the sensitivity to the consumption of gas and liquid have been defined, their static and dynamic errors, followed by the comparison of costs according to these criteria. The developed method provides accurate measurement of volumetric flow of motor fuel 1.0-1.5% at heater temperature measurement accuracy of 1%.展开更多
This paper explores the perceptions of college English teachers towards language test development, with a focus on the harmful backwash effects, specifically derived from teachers' misconceptions. Personal account...This paper explores the perceptions of college English teachers towards language test development, with a focus on the harmful backwash effects, specifically derived from teachers' misconceptions. Personal accounts of ten college teachers of English were cited and analyzed in themes, and misconceptions were identified through descriptive interpretations. The study reveals that English teachers at college are not well-acquainted with the conceptual bases for language testing due to little formal instructions. Uninformed decisions on testing and unintelligent teacher-assessment practices are potential sources of harmful backwash on teaching and learning. A dangerous tendency of reduced efforts in teacher-assessments is present among language teachers, due to blind faith in established tests, and the absence of language testing competence or excessive emphasis on High-stakes tests in research. More in-service teacher training and action research are called for.展开更多
This paper addresses estimation and its asymptotics of mean transformation θ = E[h(X)] of a random variable X based on n lid. observations from errors-in-variables model Y = X+ v, where v is a measurement error wi...This paper addresses estimation and its asymptotics of mean transformation θ = E[h(X)] of a random variable X based on n lid. observations from errors-in-variables model Y = X+ v, where v is a measurement error with a known distribution and h(.) is a known smooth function. The asymptotics of deconvolution kernel estimator for ordinary smooth error distribution and expectation extrapolation estimator are given for normal error distribution respectively. Under some mild regularity conditions, the consistency and asymptotically normality are obtained for both type of estimators. Simulations show they have good performance.展开更多
Targeted observation is an observation strategy by which the concerned phenomenon is observed. In geoscienee, targeted ob- servation is mainly related to the forecasts of weather events or predictions of climate event...Targeted observation is an observation strategy by which the concerned phenomenon is observed. In geoscienee, targeted ob- servation is mainly related to the forecasts of weather events or predictions of climate events. This paper will first review the history of targeted observation, and then introduce the main methods used in targeted observation. The discussion on the theo- retical basis of targeted observation includes its advantages and limitations. After presenting the current situation of domestic and international targeted observations in atmospheric and oceanic sciences, the methods used for targeted observation, and their effect evaluation and testing are mainly discussed here. Finally, the author presents his suggestion about the prospect of further development in the field, and how to extend the method of targeted observation to deal with numerical model errors.展开更多
Ozone pollution over the Pearl River Delta (PRD) in October 2004 has been simulated using the regional air quality models Models-3/CMAQ and CAMx. The results from both models were evaluated and compared with the obser...Ozone pollution over the Pearl River Delta (PRD) in October 2004 has been simulated using the regional air quality models Models-3/CMAQ and CAMx. The results from both models were evaluated and compared with the observed concentrations from 12 monitoring stations. By integrated process rate analysis, the influences of different physical and chemical processes were quantified, and the causes of the deviations between the two models were investigated. Both CMAQ and CAMx repro- duced the magnitudes and variations of ozone at most stations over the PRD. The correlation coefficients (R) between the sim- ulated results and monitoring data were 0.73 for CMAQ and 0.74 for CAMx. The normalized mean bias (NMB) for CMAQ and CAMx over the 12 sites was ?8.5% and 8.8% on average, respectively. The normalized mean error (NME) for CMAQ and CAMx was 36.7% and 37.9%, respectively. The correlation between the results of two models was very high (R = 0.92), and their simulated ozone spatial distributions exhibited common features. But the values obtained using CMAQ simulation were about 17% lower than those obtained using CAMx on average. The results of simulations using the two models were not identical in certain regions, or for different types of monitoring stations. The differences in dry deposition, reaction parameters and vertical transport near the Pearl River Estuary can account for the discrepancies in the results obtained using the two models. In the upwind areas, the discrepancy in the boundary concentration of the finest nest was the main cause of the higher values obtained using CAMx compared with those obtained using CMAQ. There is a need for CAMx to provide more choices of dry deposition algo- rithms. Improvement of the calculation methods for photolysis rates would also improve the ozone simulation of CMAQ.展开更多
The accuracy of daily mean 2 meter air temperatures from five reanalyses are assessed against in-situ observations from Automatic Weather Stations in East Antarctica for 2005 to 2008. The five reanalyses all explain m...The accuracy of daily mean 2 meter air temperatures from five reanalyses are assessed against in-situ observations from Automatic Weather Stations in East Antarctica for 2005 to 2008. The five reanalyses all explain more than 70% of the average variance, and have annual root mean square errors (RMSE) between 3.4 and 6.9℃. The NOAA reanalyses, NCEP-1, NCEP-2 and 20CRv2, have cool biases of 2.5, 1.4 and 1.5℃, respectively. The ERA Interim and JCDAS reanalyses have warm biases of 1.7 and 2.0℃. All reanalyses generally perform better in the austral spring and worse in winter and autumn. They also show the best performance at an inland plateau site at 2800 m elevation, but are worst at Dome A, the summit of the East Antarctic ice sheet. In general, ERA Interim is superior to the other reanalyses, probably because of its 4D assimilation scheme. The three NOAA reanalyses perform worst; Their assimilation scheme is more constrained by limited observations and 20CRy2 has less input data, assimilating only surface pressure observations. Despite deficiencies and limitations, the reanalyses are still powerful tools for climate studies in the Antarctic region. However, more in-situ observations are required, especially from the vast interior of Antarctica.展开更多
This paper studies the relationships of the monetary policy, stock market and real investment in China based on Markov-Switching-Vector Error Correction Model. It shows that there is a cointegration relationship among...This paper studies the relationships of the monetary policy, stock market and real investment in China based on Markov-Switching-Vector Error Correction Model. It shows that there is a cointegration relationship among the three ones. We disclose the riddle that the stock market is in recession, but the growth rate of economy is very high in recent years. We also find that Chinese economy operated stably most of the time during the past 8 years. But if the economy is difficult to continue its high growth, it is more likely to appear "hard landing" than "soft landing". The impulse response analysis indicates the asymmetry between the "too cold" economy regime and the "too hot" regime. And the economy will oscillate during the subsequent time when it is shocked under the "too hot" regime.展开更多
基金Supported by the Natural Science Foundation of Jiangxi Province(2009GZC0104)the Science and Technology Research Project of Jiangxi Provincial Department of Education(GJJ10521)~~
文摘Proper fixture design is crucial to obtain the better product quality according to the design specification during the workpiece fabrication. Locator layout planning is one of the most important tasks in the fixture design process. However, the design of a fixture relies heavily on the designerts expertise and experience up to now. Therefore, a new approach to loeator layout determination for workpieces with arbitrary complex surfaces is pro- posed for the first time. Firstly, based on the fuzzy judgment method, the proper locating reference and locator - numbers are determined with consideration of surface type, surface area and position tolerance. Secondly, the lo- cator positions are optimized by genetic algorithm(GA). Finally, a typical example shows that the approach is su- perior to the experiential method and can improve positioning accuracy effectively.
文摘This paper discusses some issues on human reliability model of time dependent human behavior. Some results of the crew reliability experiment on Tsinghua training simulator in China are given, Meanwhile, a case of calculation for human error probability during anticipated transient without scram (ATWS) based on the data drew from the recent experiment is offered.
基金Supported by the National Natural Science Foundation of China (No.60572036).
文摘In this letter,the sensitivity of an uplink Multi-Tone Code-Division Multiple Access (MT-CDMA) system to the Carrier Frequency Offset (CFO) is investigated. The analytical expression for the Bit Error Rate (BER) of uplink MT-CDMA in the presence of CFO is derived in a multipath Rayleigh fading channel which is verified through simulations. Both Maximal Ratio Combining (MRC) and Equal Gain Combining (EGC) are considered in combining multipath signals in the analysis. It is found that the BER performance can be improved with the number of multipath increasing in the presence of CFO.
文摘We present the application of Support Vector Machine (SVM) for the prediction of blast induced ground vibration by taking into consideration of maximum charge per delay and distance between blast face to monitoring point. To investigate the suitability of this approach, the predictions by SVM have been compared with conventional predictor equations. Blast vibration study was carried out at Magnesite mine of Pithoragarh, India. Total 170 blast vibrations data sets were recorded at different strate-gic and vulnerable locations in and around to mine. Out of 170 data sets, 150 were used for the training of the SVM network as well as to determine site constants of different conventional predictor equations, whereas, 20 new randomly selected data sets were used to compare the prediction capability of SVM network with conventional predictor equations. Results were compared based on Co-efficient of Determination (CoD) and Mean Absolute Error (MAE) between monitored and predicted values of Peak Particle Veloc-ity (PPV). It was found that SVM gives closer values of predicted PPV as compared to conventional predictor equations. The coef-ficient of determination between measured and predicted PPV by SVM was 0.955, whereas it was 0.262, 0.163, 0.337 and 0.232 by USBM, Langefors-Kihlstrom, Ambraseys-Hendron and Bureau of Indian Standard equations, respectively. The MAE for PPV was 11.13 by SVM, whereas it was 0.973, 1.088, 0.939 and 1.292 by USBM, Langefors-Kihlstrom, Ambraseys-Hendron and Bureau of Indian Standard equations respectively.
基金supported by the Special Scientific Research Fund of the Meteorological Public Welfare Profession of China[grant number GYHY01406021]National Key Research and Development Program[grant number 2016YFC0402702]the National Natural Science Foundation of China[grant numbers 41575095,41175073]
文摘Using lAP AGCM simulation results for the period 1961-2005, summer hot days in China were calculated and then compared with observations. Generally, the spatial pattern of hot days is reasonably reproduced, with more hot days found in northern China, the Yangtze and Huaihe River basin, the Chuan-Yu region, and southern Xinjiang. However, the model tends to overestimate the number of hot days in the above-mentioned regions, particularly in the Yangtze and Huaihe River basin where the simulated summer-mean hot days is 13 days more than observed when averaged over the whole region, and the maximum overestimation of hot days can reach 23 days in the region. Analysis of the probability distribution of daily maximum temperature (Trnax) suggests that the warm bias in the model-simulated Tmax contributes largely to the overestimation of hot days in the model. Furthermore, the discrepancy in the simulated variance of the Tmax distribution also plays a non- negligible role in the overestimation of hot days. Indeed, the latter can even account for 22% of the total bias of simulated hot days in August in the Yangtze and Huaihe River basin. The quantification of model bias from the mean value and variability can provide more information for further model improvement.
文摘Accompanying the arrival of new technological and network ear, SACs (self-access centers) become the most widely adopted mode spreading in China with a large quantity of universities joining to follow the fashion. But whether the SACs in China can fully fulfill the purpose, to what extend can learners gain benefits to develop autonomy, and what are the possible ways for improvement are quite necessary to investigate since there starts to emerge various problems during the implementation of SACs. This paper aims to analyze the prevalent establishment of SACs in China in order to find out the reasons for prevalence, the current implementing mode, the degree of effectiveness on developing learner autonomy, especially potential problems and causes, and finally put forward some suggestions pedagogical implications for improving.
基金supported by the National Key Basic Research and Development Program(2010CB950404)the National High Technology Research and Development Program(2013AA09A506)
文摘The effects of the mixing of wave transport flux residual(Bvl) on the upper ocean is studied through carrying out the control run(CR) and a series of sensitive runs(SR) with ROMS model.In this study,the important role of Bvl is revealed by comparing the ocean temperature,statistical analysis of errors and evaluating the mixed layer depth.It is shown that the overestimated SST is improved effectively when the wave-induced mixing is incorporated to the vertical mixing scheme.As can be seen from the vertical structure of temperature 28℃ isotherm changes from 20 min CR to 35 m in SR3,which is more close to the observation.Statistic analysis shows that the root-mean-square errors of the temperature in 10 m are reduced and the correlation between model results and observation data are increased after considering the effect of Bvl.The numerical results of the ocean temperature show improvement in summer and in tropical zones in winter,especially in the strong current regions in summer.In August the mixed layer depth(MLD) which is defined as the depth that the temperature has changed 0.5℃ from the reference depth of 10 m is further analyzed.The simulation results have a close relationship with undetermined coefficient of Bvl,sensitivity studies show that a coefficient about 0.1 is reasonable value in the model.
基金support of the Warm Temperate and Subtropical Forest Research Center, Korea Forest Research Institute
文摘This study was conducted to evaluate the performance of the four stem taper models on Camellia japonica in Jeju Island, Korea using fit statistics and lack-of-fit statistics. The five statistical criteria that were used in this study were standard error of estimate(SEE), mean bias( E), absolute mean difference(AMD), coefficient of determination(R2), and root mean square error(RMSE). Results showed that the Kozak model 02 stem taper had the best performance in all fit statistics(SEE: 3.4708, E : 0.0040 cm, AMD : 0.9060 cm, R2 : 0.9870, and RMSE : 1.2545). On the other hand, Max and Burkhart stem taper model had the poorest performance in each statistical criterion(SEE: 4.2121, E : 0.2520 cm, AMD : 1.1300 cm, R2 : 0.9805, and RMSE: 1.5317). For the lack-of-fit statistics, the Kozak model 02 also provided the best performance having the best AMD in most of the relative height classes for diameter outside bark prediction and in most of the DBH classes for total volume prediction while Max and Burkhart had the poorest performance. These stem taper equations could help forest managers to better estimate the diameter outside bark at any given height, merchantable stem volumes and total stem volumes of the standing trees of Camellia japonica in the forests of Jeju Island, Korea.
文摘The heat parameters, the thermoanemometric flow-meter (TAF) errors and the experimental characteristics have been defined. The results of experiments were conducted with the help of physically-informational models allowing to realize all major thermal methods and their inherent informative options. The metrological evaluation was made and the sensitivity to the consumption of gas and liquid have been defined, their static and dynamic errors, followed by the comparison of costs according to these criteria. The developed method provides accurate measurement of volumetric flow of motor fuel 1.0-1.5% at heater temperature measurement accuracy of 1%.
文摘This paper explores the perceptions of college English teachers towards language test development, with a focus on the harmful backwash effects, specifically derived from teachers' misconceptions. Personal accounts of ten college teachers of English were cited and analyzed in themes, and misconceptions were identified through descriptive interpretations. The study reveals that English teachers at college are not well-acquainted with the conceptual bases for language testing due to little formal instructions. Uninformed decisions on testing and unintelligent teacher-assessment practices are potential sources of harmful backwash on teaching and learning. A dangerous tendency of reduced efforts in teacher-assessments is present among language teachers, due to blind faith in established tests, and the absence of language testing competence or excessive emphasis on High-stakes tests in research. More in-service teacher training and action research are called for.
基金This research is supported by the National Natural Science Foundation of China(Grant No. 19771011 and 10071009) the RFDP (No. 20020027010) of MOE.
文摘This paper addresses estimation and its asymptotics of mean transformation θ = E[h(X)] of a random variable X based on n lid. observations from errors-in-variables model Y = X+ v, where v is a measurement error with a known distribution and h(.) is a known smooth function. The asymptotics of deconvolution kernel estimator for ordinary smooth error distribution and expectation extrapolation estimator are given for normal error distribution respectively. Under some mild regularity conditions, the consistency and asymptotically normality are obtained for both type of estimators. Simulations show they have good performance.
基金sponsored by the National Natural Science Foundation of China(Grant No.41230420)the National Basic Research Program of China(Grant No.2012CB417404)
文摘Targeted observation is an observation strategy by which the concerned phenomenon is observed. In geoscienee, targeted ob- servation is mainly related to the forecasts of weather events or predictions of climate events. This paper will first review the history of targeted observation, and then introduce the main methods used in targeted observation. The discussion on the theo- retical basis of targeted observation includes its advantages and limitations. After presenting the current situation of domestic and international targeted observations in atmospheric and oceanic sciences, the methods used for targeted observation, and their effect evaluation and testing are mainly discussed here. Finally, the author presents his suggestion about the prospect of further development in the field, and how to extend the method of targeted observation to deal with numerical model errors.
基金supported by theNational High Technology Research and Development Program of China (2006AA06A306 & 2006AA06A308)a special fund of the State Key Joint Laboratory of Environmental Simulation and Pollution Controlthe European Commission Framework Program 7 Project CityZen (212095)
文摘Ozone pollution over the Pearl River Delta (PRD) in October 2004 has been simulated using the regional air quality models Models-3/CMAQ and CAMx. The results from both models were evaluated and compared with the observed concentrations from 12 monitoring stations. By integrated process rate analysis, the influences of different physical and chemical processes were quantified, and the causes of the deviations between the two models were investigated. Both CMAQ and CAMx repro- duced the magnitudes and variations of ozone at most stations over the PRD. The correlation coefficients (R) between the sim- ulated results and monitoring data were 0.73 for CMAQ and 0.74 for CAMx. The normalized mean bias (NMB) for CMAQ and CAMx over the 12 sites was ?8.5% and 8.8% on average, respectively. The normalized mean error (NME) for CMAQ and CAMx was 36.7% and 37.9%, respectively. The correlation between the results of two models was very high (R = 0.92), and their simulated ozone spatial distributions exhibited common features. But the values obtained using CMAQ simulation were about 17% lower than those obtained using CAMx on average. The results of simulations using the two models were not identical in certain regions, or for different types of monitoring stations. The differences in dry deposition, reaction parameters and vertical transport near the Pearl River Estuary can account for the discrepancies in the results obtained using the two models. In the upwind areas, the discrepancy in the boundary concentration of the finest nest was the main cause of the higher values obtained using CAMx compared with those obtained using CMAQ. There is a need for CAMx to provide more choices of dry deposition algo- rithms. Improvement of the calculation methods for photolysis rates would also improve the ozone simulation of CMAQ.
基金funded by the Major State Basic Research Development Program of China (Grant No. 2013CBA01804)the National Natural Science Foundation of China (Grant Nos. 41121001, 40801027)the State Key Laboratory of Cryospheric Sciences (Grant No. SKLCS-ZZ- 2012-01-07)
文摘The accuracy of daily mean 2 meter air temperatures from five reanalyses are assessed against in-situ observations from Automatic Weather Stations in East Antarctica for 2005 to 2008. The five reanalyses all explain more than 70% of the average variance, and have annual root mean square errors (RMSE) between 3.4 and 6.9℃. The NOAA reanalyses, NCEP-1, NCEP-2 and 20CRv2, have cool biases of 2.5, 1.4 and 1.5℃, respectively. The ERA Interim and JCDAS reanalyses have warm biases of 1.7 and 2.0℃. All reanalyses generally perform better in the austral spring and worse in winter and autumn. They also show the best performance at an inland plateau site at 2800 m elevation, but are worst at Dome A, the summit of the East Antarctic ice sheet. In general, ERA Interim is superior to the other reanalyses, probably because of its 4D assimilation scheme. The three NOAA reanalyses perform worst; Their assimilation scheme is more constrained by limited observations and 20CRy2 has less input data, assimilating only surface pressure observations. Despite deficiencies and limitations, the reanalyses are still powerful tools for climate studies in the Antarctic region. However, more in-situ observations are required, especially from the vast interior of Antarctica.
文摘This paper studies the relationships of the monetary policy, stock market and real investment in China based on Markov-Switching-Vector Error Correction Model. It shows that there is a cointegration relationship among the three ones. We disclose the riddle that the stock market is in recession, but the growth rate of economy is very high in recent years. We also find that Chinese economy operated stably most of the time during the past 8 years. But if the economy is difficult to continue its high growth, it is more likely to appear "hard landing" than "soft landing". The impulse response analysis indicates the asymmetry between the "too cold" economy regime and the "too hot" regime. And the economy will oscillate during the subsequent time when it is shocked under the "too hot" regime.