In order to investigate the stability problem of shield tunnel faces subjected to seismic loading,the pseudodynamic method(P-DM)was employed to analyze the seismic effect on the face.Two kinds of failure mechanisms of...In order to investigate the stability problem of shield tunnel faces subjected to seismic loading,the pseudodynamic method(P-DM)was employed to analyze the seismic effect on the face.Two kinds of failure mechanisms of active collapse and passive extrusion were considered,and a seismic reliability model of shield tunnel faces under multifailure mode was established.The limit analysis method and the response surface method(RSM)were used together to solve the reliability of shield tunnel faces subjected to seismic action.Comparing with existing results,the results of this work are effective.The effects of seismic load and rock mass strength on the collapse pressure,extrusion pressure and reliability index were discussed,and reasonable ranges of support pressure of shield tunnel faces under seismic action were presented.This method can provide a new idea for solving the shield thrust parameter under the seismic loading.展开更多
This study investigates the impact of global warming on drought/flood patterns in China at the end of the 21st century based on the simulations of 22 global climate models and a regional climate model(RegCM3) under th...This study investigates the impact of global warming on drought/flood patterns in China at the end of the 21st century based on the simulations of 22 global climate models and a regional climate model(RegCM3) under the SRES(Special Report on Emissions Scenarios) A1B scenario.The standardized precipitation index(SPI),which has well performance in monitoring the drought/flood characteristics(in terms of their intensity,duration,and spatial extent) in China,is used in this study.The projected results of 22 coupled models and the RegCM3 simulation are consistent.These models project a decrease in the frequency of droughts in most parts of northern China and a slight increase in the frequency in some parts of southern China.Considering China as a whole,the spatial extents of droughts are projected to be significantly reduced.In contrast,future flood events over most parts of China are projected to occur more frequently with stronger intensity and longer duration than those prevalent currently.Additionally,the spatial extents of flood events are projected to significantly increase.展开更多
A local and global context representation learning model for Chinese characters is designed and a Chinese word segmentation method based on character representations is proposed in this paper. First, the proposed Chin...A local and global context representation learning model for Chinese characters is designed and a Chinese word segmentation method based on character representations is proposed in this paper. First, the proposed Chinese character learning model uses the semanties of loeal context and global context to learn the representation of Chinese characters. Then, Chinese word segmentation model is built by a neural network, while the segmentation model is trained with the eharaeter representations as its input features. Finally, experimental results show that Chinese charaeter representations can effectively learn the semantic information. Characters with similar semantics cluster together in the visualize space. Moreover, the proposed Chinese word segmentation model also achieves a pretty good improvement on precision, recall and f-measure.展开更多
In order to eliminate the drawbacks of conventional force feedback gloves, a new type of master fin- ger has been developed. By utilizing three ＂four-bar mechanism joint＂ in series and wire coupling mecha- nism, the...In order to eliminate the drawbacks of conventional force feedback gloves, a new type of master fin- ger has been developed. By utilizing three ＂four-bar mechanism joint＂ in series and wire coupling mecha- nism, the master finger transmission ratio is kept exactly 1：1.4：1 in the whole movement range and it can make active motions in both extension and flexion directions. Additionally, to assure faster data transmission and near zero delay in the master-slave operation, a digital signal processing/field programmable gate array （DSP/FPGA-FPGA） structure with 200μs cycle time is designed. The operating modes of the master finger can be contact or non-contact, which depends on the motion states of a slave finger, free motion or constrained motion. The position control employed in non-contact mode ensures unconstrained motion and the force control adopted in contact mode guarantees natural contact sensation. To evaluate the performances of the master finger, an experiment between the master finger and a DLR/HTT dexterous finger is conducted. The results demonstrate that this new type master finger can augment telepresence.展开更多
Filtration processes are worldwide used for sterilizing solutions and substrates. Filtration seems to induce the formation of aqueous nanostructures. The aim of this work was to verify the influence of filtration proc...Filtration processes are worldwide used for sterilizing solutions and substrates. Filtration seems to induce the formation of aqueous nanostructures. The aim of this work was to verify the influence of filtration processes on water structure detected by spectral variations in NIR region. Samples of ultrapure water （MilliQ-Millipore, Vimodrone, Milan, Italy） before and after iterated filtrations were analyzed. NIR spectra were collected in transmission mode in the whole NIR range, by using NIRFIex N500 spectrometer at constant temperature （40 ± 1 ℃）. NIR data were processed using Unscrambler software v. 9.2 in evaluating qualitative differences between filtered and not filtered samples. The information related to possible solvent physical stresses were highlighted in the range 6500-7500 cm^-1. The shifts observed were ascribable to a different distribution of the number of water molecules involved in hydrogen bonds in filtered and not filtered water samples, at constant temperature. NIR spectroscopy, commonly used to study relationship between spectral changes and hydrogen bonds in water at increasing temperature values, was applied to evaluate effects of filtration processes on water structure. The obtained results are in agreement with literature data and allowed the improvement of the knowledge about pure water characteristics when some mechanical perturbations are applied.展开更多
A highly sensitive in-situ turbidity sensor with the low power consumption was proposed and evaluated in this study. To meet the practical requirements of the in-situ detection, we have designed the light scattering p...A highly sensitive in-situ turbidity sensor with the low power consumption was proposed and evaluated in this study. To meet the practical requirements of the in-situ detection, we have designed the light scattering path, watertight mechanical structure, and ultra-weak scattering light detecting method. Experiments showed that the sensor had a sensitivity of 0.0076 FTU with the concentration range of 0 - 25 FTU and the R-square of 0.9999. The sensor could withstand the water pressure in depth of 1000m and had the low power consumption in the active mode 10.4mA, sleep mode 65 pA with a supply voltage of 8.4V. Southern China Sea buoy experiments indicated that the sensor could work well in the actual in-situ environment. In comparison with sensors of other companies, our sensor had relatively more comprehensive performance.展开更多
The mode splitting in a system with Doppler-broadened high-density two-level atoms in the presence of magnetic field inside a relatively long optical cavity is studied in the superstrong coupling regime(atoms-cavity c...The mode splitting in a system with Doppler-broadened high-density two-level atoms in the presence of magnetic field inside a relatively long optical cavity is studied in the superstrong coupling regime(atoms-cavity coupling strength g√N is near or larger than the cavity free-spectral range?FSR).The effect of a magnetic field applied along the quantization axis is used to break the polarization degeneracy of the cavity and thereby introduce birefringence(or Faraday rotation)into the medium.The cavity modes are further split in the presence of the magnetic field compared with the normal case of the multi-normal-mode splitting of the two-level system near the D2 line of87Rb.The dependence of the mode splitting on the magnetic field and the temperature is studied.The theoretical analysis according to the linear dispersion theory can provide a good explanation.展开更多
Drifting can be an effective way for aquatic organisms to disperse and colonise new areas. Increasing connectivity between European large rivers facilitates invasion by drifting aquatic macroinvertebrates. The present...Drifting can be an effective way for aquatic organisms to disperse and colonise new areas. Increasing connectivity between European large rivers facilitates invasion by drifting aquatic macroinvertebrates. The present study shows that high abundances of invasive species drift in the headstream of the river Rhine. Dikerogammarus villosus and Chelicorophium cur- vispinum represented up to 90% of the total of drifting macroinvertebrates. Drift activity shows seasonal and diel patterns. Most species started drifting in spring and were most abundant in the water column during the summer period. Drift activity was very low during the winter period. Diel patterns were apparent; most species, including D. villosus, drifted during the night. Drifting macroinvertebrates colonised stony substrate directly from the water column. D. villosus generally colonised the substrate at night, while higher numbers of C. curvispinum colonised the substrate during the day. It is very likely that drifting functions as a disper- sal mechanism for crustacean invaders. Once waterways are connected, these species are no longer necessarily dependent on dispersal vectors other than drift for extending their distribution range展开更多
Objective：Fracture of either radius or ulna with a dislocation either at the proximal or distal radioulnar joint （DRUJ） is not a common injury and is inherently unstable.Here we report a case series,with both-bone ...Objective：Fracture of either radius or ulna with a dislocation either at the proximal or distal radioulnar joint （DRUJ） is not a common injury and is inherently unstable.Here we report a case series,with both-bone forearm fractures associated with dislocation of DRUJ,as a Galeazzi-variant type fracture-dislocation,and try to analyze this injury pattern.Methods：The study was based on 6 patients having Galeazzi-variant type fracture-dislocation of different age （20 to 45 years）.All fractures were closed type.Two fractures involved the same level and three fractures were at different levels of radius and ulna shaft.After thorough examination and investigations they were treated with limited contact dynamic compression plate without additional fixation for DRUJ.Results：All cases were followed up for 24 weeks.The maximum incidence occurred in age group between 31 and 40 years.All the fractures of both radius and ulna were united in average time of 12 weeks.Range of motion of wrist and elbow,supination and pronation at final follow-up were normal.There was no subsequent re-subluxation or dislocation of the DRUJ in any of the cases.Conclusion：Galeazzi variant in adult is a new undescribed pattern of forearm with wrist injury.Stable open reduction and internal fixation of both-bone forearm fractures is mandatory,followed by 3 to 4 weeks of immobilization in a cast for the healing of disrupted DRUJ.展开更多
基金Projects(51804113,52074116)supported by the National Natural Science Foundation of ChinaProject(2020M682563)supported by the China Postdoctoral Science Foundation+1 种基金Project(19C0743)supported by the Scientific Research Foundation of Hunan Provincial Education Department,ChinaProject(E52076)supported by the Science Foundation of Hunan University of Science and Technology,China。
文摘In order to investigate the stability problem of shield tunnel faces subjected to seismic loading,the pseudodynamic method(P-DM)was employed to analyze the seismic effect on the face.Two kinds of failure mechanisms of active collapse and passive extrusion were considered,and a seismic reliability model of shield tunnel faces under multifailure mode was established.The limit analysis method and the response surface method(RSM)were used together to solve the reliability of shield tunnel faces subjected to seismic action.Comparing with existing results,the results of this work are effective.The effects of seismic load and rock mass strength on the collapse pressure,extrusion pressure and reliability index were discussed,and reasonable ranges of support pressure of shield tunnel faces under seismic action were presented.This method can provide a new idea for solving the shield thrust parameter under the seismic loading.
基金supported by the National Basic Research Program of China (Grant No. 2012CB955401)the National Natural Science Foundation of China (Grant No. 41275078)supported by the "Strategic Priority Research Program-Climate Change:Carbon Budget and Relevant Issues" of the Chinese Academy of Sciences (Grant No. XDA05090306)
文摘This study investigates the impact of global warming on drought/flood patterns in China at the end of the 21st century based on the simulations of 22 global climate models and a regional climate model(RegCM3) under the SRES(Special Report on Emissions Scenarios) A1B scenario.The standardized precipitation index(SPI),which has well performance in monitoring the drought/flood characteristics(in terms of their intensity,duration,and spatial extent) in China,is used in this study.The projected results of 22 coupled models and the RegCM3 simulation are consistent.These models project a decrease in the frequency of droughts in most parts of northern China and a slight increase in the frequency in some parts of southern China.Considering China as a whole,the spatial extents of droughts are projected to be significantly reduced.In contrast,future flood events over most parts of China are projected to occur more frequently with stronger intensity and longer duration than those prevalent currently.Additionally,the spatial extents of flood events are projected to significantly increase.
基金Supported by the National Natural Science Foundation of China(No.61303179,U1135005,61175020)
文摘A local and global context representation learning model for Chinese characters is designed and a Chinese word segmentation method based on character representations is proposed in this paper. First, the proposed Chinese character learning model uses the semanties of loeal context and global context to learn the representation of Chinese characters. Then, Chinese word segmentation model is built by a neural network, while the segmentation model is trained with the eharaeter representations as its input features. Finally, experimental results show that Chinese charaeter representations can effectively learn the semantic information. Characters with similar semantics cluster together in the visualize space. Moreover, the proposed Chinese word segmentation model also achieves a pretty good improvement on precision, recall and f-measure.
文摘In order to eliminate the drawbacks of conventional force feedback gloves, a new type of master fin- ger has been developed. By utilizing three ＂four-bar mechanism joint＂ in series and wire coupling mecha- nism, the master finger transmission ratio is kept exactly 1：1.4：1 in the whole movement range and it can make active motions in both extension and flexion directions. Additionally, to assure faster data transmission and near zero delay in the master-slave operation, a digital signal processing/field programmable gate array （DSP/FPGA-FPGA） structure with 200μs cycle time is designed. The operating modes of the master finger can be contact or non-contact, which depends on the motion states of a slave finger, free motion or constrained motion. The position control employed in non-contact mode ensures unconstrained motion and the force control adopted in contact mode guarantees natural contact sensation. To evaluate the performances of the master finger, an experiment between the master finger and a DLR/HTT dexterous finger is conducted. The results demonstrate that this new type master finger can augment telepresence.
文摘Filtration processes are worldwide used for sterilizing solutions and substrates. Filtration seems to induce the formation of aqueous nanostructures. The aim of this work was to verify the influence of filtration processes on water structure detected by spectral variations in NIR region. Samples of ultrapure water （MilliQ-Millipore, Vimodrone, Milan, Italy） before and after iterated filtrations were analyzed. NIR spectra were collected in transmission mode in the whole NIR range, by using NIRFIex N500 spectrometer at constant temperature （40 ± 1 ℃）. NIR data were processed using Unscrambler software v. 9.2 in evaluating qualitative differences between filtered and not filtered samples. The information related to possible solvent physical stresses were highlighted in the range 6500-7500 cm^-1. The shifts observed were ascribable to a different distribution of the number of water molecules involved in hydrogen bonds in filtered and not filtered water samples, at constant temperature. NIR spectroscopy, commonly used to study relationship between spectral changes and hydrogen bonds in water at increasing temperature values, was applied to evaluate effects of filtration processes on water structure. The obtained results are in agreement with literature data and allowed the improvement of the knowledge about pure water characteristics when some mechanical perturbations are applied.
文摘A highly sensitive in-situ turbidity sensor with the low power consumption was proposed and evaluated in this study. To meet the practical requirements of the in-situ detection, we have designed the light scattering path, watertight mechanical structure, and ultra-weak scattering light detecting method. Experiments showed that the sensor had a sensitivity of 0.0076 FTU with the concentration range of 0 - 25 FTU and the R-square of 0.9999. The sensor could withstand the water pressure in depth of 1000m and had the low power consumption in the active mode 10.4mA, sleep mode 65 pA with a supply voltage of 8.4V. Southern China Sea buoy experiments indicated that the sensor could work well in the actual in-situ environment. In comparison with sensors of other companies, our sensor had relatively more comprehensive performance.
基金supported by the National Basic Research Program of China(Grant No.2011CB921601)the National Natural Science Foundation of China(Grant No.11234008)+1 种基金the NSFC Project for Excellent Research Team(Grant Nos.61121064 and 11234008)the Doctoral Program Founda-tion of the Ministry of Education China(Grant No.20111401130001)
文摘The mode splitting in a system with Doppler-broadened high-density two-level atoms in the presence of magnetic field inside a relatively long optical cavity is studied in the superstrong coupling regime(atoms-cavity coupling strength g√N is near or larger than the cavity free-spectral range?FSR).The effect of a magnetic field applied along the quantization axis is used to break the polarization degeneracy of the cavity and thereby introduce birefringence(or Faraday rotation)into the medium.The cavity modes are further split in the presence of the magnetic field compared with the normal case of the multi-normal-mode splitting of the two-level system near the D2 line of87Rb.The dependence of the mode splitting on the magnetic field and the temperature is studied.The theoretical analysis according to the linear dispersion theory can provide a good explanation.
文摘Drifting can be an effective way for aquatic organisms to disperse and colonise new areas. Increasing connectivity between European large rivers facilitates invasion by drifting aquatic macroinvertebrates. The present study shows that high abundances of invasive species drift in the headstream of the river Rhine. Dikerogammarus villosus and Chelicorophium cur- vispinum represented up to 90% of the total of drifting macroinvertebrates. Drift activity shows seasonal and diel patterns. Most species started drifting in spring and were most abundant in the water column during the summer period. Drift activity was very low during the winter period. Diel patterns were apparent; most species, including D. villosus, drifted during the night. Drifting macroinvertebrates colonised stony substrate directly from the water column. D. villosus generally colonised the substrate at night, while higher numbers of C. curvispinum colonised the substrate during the day. It is very likely that drifting functions as a disper- sal mechanism for crustacean invaders. Once waterways are connected, these species are no longer necessarily dependent on dispersal vectors other than drift for extending their distribution range
文摘Objective：Fracture of either radius or ulna with a dislocation either at the proximal or distal radioulnar joint （DRUJ） is not a common injury and is inherently unstable.Here we report a case series,with both-bone forearm fractures associated with dislocation of DRUJ,as a Galeazzi-variant type fracture-dislocation,and try to analyze this injury pattern.Methods：The study was based on 6 patients having Galeazzi-variant type fracture-dislocation of different age （20 to 45 years）.All fractures were closed type.Two fractures involved the same level and three fractures were at different levels of radius and ulna shaft.After thorough examination and investigations they were treated with limited contact dynamic compression plate without additional fixation for DRUJ.Results：All cases were followed up for 24 weeks.The maximum incidence occurred in age group between 31 and 40 years.All the fractures of both radius and ulna were united in average time of 12 weeks.Range of motion of wrist and elbow,supination and pronation at final follow-up were normal.There was no subsequent re-subluxation or dislocation of the DRUJ in any of the cases.Conclusion：Galeazzi variant in adult is a new undescribed pattern of forearm with wrist injury.Stable open reduction and internal fixation of both-bone forearm fractures is mandatory,followed by 3 to 4 weeks of immobilization in a cast for the healing of disrupted DRUJ.
