-Using the COADS data set of sea surface temperature in the Equatorial Eastern Pacific, thirty one El Nino events and twenty four anti -El Nino events were identified for the period from 1854 to 1987. The results were...-Using the COADS data set of sea surface temperature in the Equatorial Eastern Pacific, thirty one El Nino events and twenty four anti -El Nino events were identified for the period from 1854 to 1987. The results were compared with those of the other authors. The El Nino events (or anti -El Nino events ) are classified into two groups according to the timing of occrrence of the events: one starts at the first half of a year, another begins at the second half of a year. Both 1982-1983 and 1986-1987 events fall into the second group, which are characterized by the eastward migration of the positive anomaly of the sea surface temperature and the significant increasing of the anomaly in September or October.展开更多
We describe the last glaciation climatic history Marine Isotope Stage(MIS, 2-4) from 66.7 ka to 14.5 ka in Hexigten, northeast Inner Mongolia, North China. The climate of the region experienced frequent and significan...We describe the last glaciation climatic history Marine Isotope Stage(MIS, 2-4) from 66.7 ka to 14.5 ka in Hexigten, northeast Inner Mongolia, North China. The climate of the region experienced frequent and significant fluctuations between dry-cold and less dry-cold during the late MIS4. The climate was generally warm and humid during early MIS3(MIS3 c) and late MIS3(MIS3 a), whereas it was cold and dry in middle MIS3(MIS3 b) and during MIS2. In this study, the cold and dry conditions were correlated with a stronger East Asian winter monsoon and strong dune activity; whereas, warm and humid conditions were related to a stronger East Asian summer monsoon(EASM) and weak dune activity. This study establishes six distinct dry and cold intervals during the last glacial period(66.7-14.5 ka) based on optically stimulated luminescence data, multi-proxies record(magnetic susceptibility, grain size analysis, Rb/Sr, SiO2/TiO2) and chemical index of alteration(CIA). The last glacial period may be correlated with Heinrich events 1 to 6 which were further confirmed by comparison with the Hulu cave stalagmites and Greenland ice core records. It is concluded that the study area was substantially affected by the EASM, as compared with the loess-desert transition zone of the Chinese Loess Plateau, especially in MIS3 c and suggested that the East Asian monsoon played a pivotal role in the last glacial period climate and dune activity.展开更多
In this paper, the winter atmospheric circulation, the convection along the equator and their variations of 1982 and 1983 are investigated. It is suggested that there was a well organized three dimensional structure o...In this paper, the winter atmospheric circulation, the convection along the equator and their variations of 1982 and 1983 are investigated. It is suggested that there was a well organized three dimensional structure of anomalies of the atmospheric circulations during 1982 winter which may be related to the variations of the convection in the equatorial region.展开更多
Shaw's method used to correlate 40 sections across the Permo-Triassic boundary in South China is applied in the paper. Two steps are adopted to get an Integral Composite Section (ICS) by synthesizing these data : ...Shaw's method used to correlate 40 sections across the Permo-Triassic boundary in South China is applied in the paper. Two steps are adopted to get an Integral Composite Section (ICS) by synthesizing these data : First , South China is divided into five areas and composite section developed for each area . Then the second step . the Changxing composite section is regarded as a composite standard (CSRS) while the ICS is produced by matching the CSRS with composite sections of the other areas. Three biozones in the Changxingian and two biozones in the Griesbachian can be discerned on the basis of computing Z values in the ICS. These biozones are marked by the Z values which quantitatively represent their time ranges ; therefore , they may increase accuracy of stratigraphic time correlation . The mass extinction at the end of the Permian is an abrupt event that is supported by the relative rate of extinction near the P/T boundary . About 90% of invertebrate species died out by the end of the Permian . The duration of the mass extinction is rather short ,approximately 0.018Ma .展开更多
Flood events vary with sub-regions, sites and time and show complex characteristics. This study investigated temporal variabilities in flood discharges and relationships with principal driving factors in data scarce W...Flood events vary with sub-regions, sites and time and show complex characteristics. This study investigated temporal variabilities in flood discharges and relationships with principal driving factors in data scarce Wabi Shebele River Basin. The preliminary analysis using exploratory data analysis (EDA) on annual and seasonal maximum discharge reveals that there are cycles of extreme flows at five- and ten-year intervals respectively throughout the basin. The statistical verification using the Mann-Kendall test and Quantile perturbation method indicates a significant trend in flood magnitude and frequency entire the basin in the early 21st century. For longest period (1980-2010) annual maximum stream flow shows significant positive trend (p-value < 0.05) in middle catchments and negative trend (p-value < 0.05) in eastern catchments. The years: 1986-1995, 2006-2010 are the years in which positive significant anomalies occurred in all seasons, while the years: 1980-1985, 1996-2005 are the occurrence years of significant negative anomalies. Rainfall from climate drivers;DA, BE, VS and fraction of sand from environmental background drivers;fraction of forest and population density from external factors were identified as the powerful driving factors of flood variabilities in the Wabi Shebele River Basin.展开更多
A synchronous electronic let-off and take-up device isdesigned.The device is controlled by a single-chipcomputer and driven by two step motors.It has somefunctions such as keeping the warp tension constant dur-ing the...A synchronous electronic let-off and take-up device isdesigned.The device is controlled by a single-chipcomputer and driven by two step motors.It has somefunctions such as keeping the warp tension constant dur-ing the weaving instant,releasing the warp tension whenloom is stopping and straining warp when loom is start-ing.By means of these functions,the stop mark of thewoven fabrics is eliminated.In addition,this device canapply to weaving variant-pick-density fabrics.展开更多
A new video-based measurement is proposed to collect and investigate traffic flow parameters. The output of the measurement is velocity-headway distance data pairs. Because density can be directly acquired by the reci...A new video-based measurement is proposed to collect and investigate traffic flow parameters. The output of the measurement is velocity-headway distance data pairs. Because density can be directly acquired by the reciprocal of headway distance, the data pairs have the advantage of better simultaneity than those from common detectors. By now, over 33 000 pairs of data have been collected from two road sections in the cities of Shanghai and Zhengzhou. Through analyzing the video files recording traffic movements on urban expressways, the following issues are studied：laws of vehicle velocity changing with headway distance, proportions of di0erent driving behaviors in the traffic system, and characteristics of traffic flow in snowy days. The results show that the real road traffic is very complex, and factors such as location and climate need to be taken into consideration in the formation of traffic flow models.展开更多
This paper analyzed the characteristics of welding solidification crack of stainless steels,and clearly re- vealed the the of the deformation in the molten - the pool and the solidification shrinkage on the stress -...This paper analyzed the characteristics of welding solidification crack of stainless steels,and clearly re- vealed the the of the deformation in the molten - the pool and the solidification shrinkage on the stress - strain fields in the trail of molten - weld pool.Moreover, rheologic properties of the alloys in solid - liquid zone were also obtained by measuring the hading and unloading deform curves of the steels.As a result, a numerical model for simulation of stress - strain distributions of welding solidifi- cation crack was developed. On the basis of the model,the thesis simulated the driving force of solidifi- cation crack of stainless steels, that is, stress - strain fields in the trail of molten-weld pool with fi- nite element method.展开更多
Conventional fault tree and reliability analysis do not reflect the characteristics of basic events as non stationary and ergodic process. To overcome these drawbacks, theory of fuzzy sets is employed to run fault tre...Conventional fault tree and reliability analysis do not reflect the characteristics of basic events as non stationary and ergodic process. To overcome these drawbacks, theory of fuzzy sets is employed to run fault tree analysis(FTA) of roller oscillating tooth gear drive(ROTGD), the relative frequencies of basic events are considered as symmetrical normal fuzzy numbers, from the logical relationship between different events in the fault tree and fuzzy operators AND and OR, fuzzy probability of top event is solved. Finally, an example is given to demonstrate a real ROTGD system.展开更多
"Social event driving" has become a way to promote urban development, create urban public spaces and create a city image. As one of the important big cities in northeastern China, Harbin enjoys the reputatio..."Social event driving" has become a way to promote urban development, create urban public spaces and create a city image. As one of the important big cities in northeastern China, Harbin enjoys the reputation of "The Music City", and its public space development is inextricably linked with the driving of music culture. This paper started with the analysis of the correlation between the development of urban public spaces and the development of music culture in Harbin, and studied the influence and driving role of music culture on the construction and development of urban public spaces.展开更多
The existing plastic forming equipment are mostly driven by traditional AC motors with long trans- mission chains, low efficiency, large size, low precision and poor dynamic response are the common disadvantages. In o...The existing plastic forming equipment are mostly driven by traditional AC motors with long trans- mission chains, low efficiency, large size, low precision and poor dynamic response are the common disadvantages. In order to realize high performance forming processes, the driving device should be improved, especially for com- plicated processing motions. Based on electric servo direct drive technology, a novel AC servo rotating and linear composite driving device is proposed, which features implementing both spindle rotation and feed motion with- out transmission, so that compact structure and precise control can be achieved. Flux switching topology is employed in the rotating drive component for strong robustness, and fractional slot is employed in the linear direct drive component for large force capability. Then the mechanical structure for compositing rotation and linear motion is designed. A device prototype is manufactured, machining of each component and the whole assembly are presented respectively. Commercial servo amplifiers are utilized to construct the control system of the proposed device. To validate the effectiveness of the proposed composite driving device, experimental study on thedynamic test benches are conducted. The results indicate that the output torque can attain to 420 N-m and the dynamic tracking errors are less than about 0.3 rad in the rotating drive, the dynamic tracking errors are less than about 1.6 mm in the linear feed. The proposed research provides a method to construct high efficiency and accu- racy direct driving device in plastic forming equipment.展开更多
文摘-Using the COADS data set of sea surface temperature in the Equatorial Eastern Pacific, thirty one El Nino events and twenty four anti -El Nino events were identified for the period from 1854 to 1987. The results were compared with those of the other authors. The El Nino events (or anti -El Nino events ) are classified into two groups according to the timing of occrrence of the events: one starts at the first half of a year, another begins at the second half of a year. Both 1982-1983 and 1986-1987 events fall into the second group, which are characterized by the eastward migration of the positive anomaly of the sea surface temperature and the significant increasing of the anomaly in September or October.
基金supported by the Research Fund for Hexigten Global Geopark(Grant No.62932014004)Specialized Fund for Fundamental Research Program of China University of Geosciences,Beijing(Grant No.2011YYL016)+1 种基金the Specialized Fund for Public Welfare Industry,Ministry of Land and Resources of China(Grant No.201211077-3)the Specialized Research Fund for the Doctoral Program of Higher Education of China(for PhD supervisors,Grant No.20110022110005)
文摘We describe the last glaciation climatic history Marine Isotope Stage(MIS, 2-4) from 66.7 ka to 14.5 ka in Hexigten, northeast Inner Mongolia, North China. The climate of the region experienced frequent and significant fluctuations between dry-cold and less dry-cold during the late MIS4. The climate was generally warm and humid during early MIS3(MIS3 c) and late MIS3(MIS3 a), whereas it was cold and dry in middle MIS3(MIS3 b) and during MIS2. In this study, the cold and dry conditions were correlated with a stronger East Asian winter monsoon and strong dune activity; whereas, warm and humid conditions were related to a stronger East Asian summer monsoon(EASM) and weak dune activity. This study establishes six distinct dry and cold intervals during the last glacial period(66.7-14.5 ka) based on optically stimulated luminescence data, multi-proxies record(magnetic susceptibility, grain size analysis, Rb/Sr, SiO2/TiO2) and chemical index of alteration(CIA). The last glacial period may be correlated with Heinrich events 1 to 6 which were further confirmed by comparison with the Hulu cave stalagmites and Greenland ice core records. It is concluded that the study area was substantially affected by the EASM, as compared with the loess-desert transition zone of the Chinese Loess Plateau, especially in MIS3 c and suggested that the East Asian monsoon played a pivotal role in the last glacial period climate and dune activity.
文摘In this paper, the winter atmospheric circulation, the convection along the equator and their variations of 1982 and 1983 are investigated. It is suggested that there was a well organized three dimensional structure of anomalies of the atmospheric circulations during 1982 winter which may be related to the variations of the convection in the equatorial region.
文摘Shaw's method used to correlate 40 sections across the Permo-Triassic boundary in South China is applied in the paper. Two steps are adopted to get an Integral Composite Section (ICS) by synthesizing these data : First , South China is divided into five areas and composite section developed for each area . Then the second step . the Changxing composite section is regarded as a composite standard (CSRS) while the ICS is produced by matching the CSRS with composite sections of the other areas. Three biozones in the Changxingian and two biozones in the Griesbachian can be discerned on the basis of computing Z values in the ICS. These biozones are marked by the Z values which quantitatively represent their time ranges ; therefore , they may increase accuracy of stratigraphic time correlation . The mass extinction at the end of the Permian is an abrupt event that is supported by the relative rate of extinction near the P/T boundary . About 90% of invertebrate species died out by the end of the Permian . The duration of the mass extinction is rather short ,approximately 0.018Ma .
文摘Flood events vary with sub-regions, sites and time and show complex characteristics. This study investigated temporal variabilities in flood discharges and relationships with principal driving factors in data scarce Wabi Shebele River Basin. The preliminary analysis using exploratory data analysis (EDA) on annual and seasonal maximum discharge reveals that there are cycles of extreme flows at five- and ten-year intervals respectively throughout the basin. The statistical verification using the Mann-Kendall test and Quantile perturbation method indicates a significant trend in flood magnitude and frequency entire the basin in the early 21st century. For longest period (1980-2010) annual maximum stream flow shows significant positive trend (p-value < 0.05) in middle catchments and negative trend (p-value < 0.05) in eastern catchments. The years: 1986-1995, 2006-2010 are the years in which positive significant anomalies occurred in all seasons, while the years: 1980-1985, 1996-2005 are the occurrence years of significant negative anomalies. Rainfall from climate drivers;DA, BE, VS and fraction of sand from environmental background drivers;fraction of forest and population density from external factors were identified as the powerful driving factors of flood variabilities in the Wabi Shebele River Basin.
文摘A synchronous electronic let-off and take-up device isdesigned.The device is controlled by a single-chipcomputer and driven by two step motors.It has somefunctions such as keeping the warp tension constant dur-ing the weaving instant,releasing the warp tension whenloom is stopping and straining warp when loom is start-ing.By means of these functions,the stop mark of thewoven fabrics is eliminated.In addition,this device canapply to weaving variant-pick-density fabrics.
基金supported by the National Natural Science Foundation of China (10772050)
文摘A new video-based measurement is proposed to collect and investigate traffic flow parameters. The output of the measurement is velocity-headway distance data pairs. Because density can be directly acquired by the reciprocal of headway distance, the data pairs have the advantage of better simultaneity than those from common detectors. By now, over 33 000 pairs of data have been collected from two road sections in the cities of Shanghai and Zhengzhou. Through analyzing the video files recording traffic movements on urban expressways, the following issues are studied：laws of vehicle velocity changing with headway distance, proportions of di0erent driving behaviors in the traffic system, and characteristics of traffic flow in snowy days. The results show that the real road traffic is very complex, and factors such as location and climate need to be taken into consideration in the formation of traffic flow models.
文摘This paper analyzed the characteristics of welding solidification crack of stainless steels,and clearly re- vealed the the of the deformation in the molten - the pool and the solidification shrinkage on the stress - strain fields in the trail of molten - weld pool.Moreover, rheologic properties of the alloys in solid - liquid zone were also obtained by measuring the hading and unloading deform curves of the steels.As a result, a numerical model for simulation of stress - strain distributions of welding solidifi- cation crack was developed. On the basis of the model,the thesis simulated the driving force of solidifi- cation crack of stainless steels, that is, stress - strain fields in the trail of molten-weld pool with fi- nite element method.
文摘Conventional fault tree and reliability analysis do not reflect the characteristics of basic events as non stationary and ergodic process. To overcome these drawbacks, theory of fuzzy sets is employed to run fault tree analysis(FTA) of roller oscillating tooth gear drive(ROTGD), the relative frequencies of basic events are considered as symmetrical normal fuzzy numbers, from the logical relationship between different events in the fault tree and fuzzy operators AND and OR, fuzzy probability of top event is solved. Finally, an example is given to demonstrate a real ROTGD system.
基金Sponsored by Science and Technology Plans of Ministry of Housing and Urban-Rural Development of the People’s Republic of China,and Opening Projects of Beijing Advanced Innovation Center for Future Urban Design,Beijing University of Civil Engineering and Architecture(UDC2017030712)2018 Beijing Municipal University Academic Human Resources Development-Youth Talent Support Program(PXM2018_014212_000043)North China University of Technology "YuYou" Talent Training Program
文摘"Social event driving" has become a way to promote urban development, create urban public spaces and create a city image. As one of the important big cities in northeastern China, Harbin enjoys the reputation of "The Music City", and its public space development is inextricably linked with the driving of music culture. This paper started with the analysis of the correlation between the development of urban public spaces and the development of music culture in Harbin, and studied the influence and driving role of music culture on the construction and development of urban public spaces.
基金Supported by National Natural Science Foundation of China(Grant No.51335009)Major National Science and Technology Project of China(Grant No.2011ZX04001-011)
文摘The existing plastic forming equipment are mostly driven by traditional AC motors with long trans- mission chains, low efficiency, large size, low precision and poor dynamic response are the common disadvantages. In order to realize high performance forming processes, the driving device should be improved, especially for com- plicated processing motions. Based on electric servo direct drive technology, a novel AC servo rotating and linear composite driving device is proposed, which features implementing both spindle rotation and feed motion with- out transmission, so that compact structure and precise control can be achieved. Flux switching topology is employed in the rotating drive component for strong robustness, and fractional slot is employed in the linear direct drive component for large force capability. Then the mechanical structure for compositing rotation and linear motion is designed. A device prototype is manufactured, machining of each component and the whole assembly are presented respectively. Commercial servo amplifiers are utilized to construct the control system of the proposed device. To validate the effectiveness of the proposed composite driving device, experimental study on thedynamic test benches are conducted. The results indicate that the output torque can attain to 420 N-m and the dynamic tracking errors are less than about 0.3 rad in the rotating drive, the dynamic tracking errors are less than about 1.6 mm in the linear feed. The proposed research provides a method to construct high efficiency and accu- racy direct driving device in plastic forming equipment.
