Hyperfine structures and the field effects of IBr molecule in its rovibronic ground state are theoretically studied by diagonalizing the effective Hamiltonian matrix.Perturbations of high-J levels up to 4 are taken in...Hyperfine structures and the field effects of IBr molecule in its rovibronic ground state are theoretically studied by diagonalizing the effective Hamiltonian matrix.Perturbations of high-J levels up to 4 are taken into account when studying the hyperfine sub-levels of the J=0 level,and thus,an 80×80 matrix is constructed and solved.Some of the experimentally absent molecular constants are computed using Dalton program.Our results will be helpful in the experimental investigation of manipulation and further cooling of cold IBr molecules.展开更多
The mixed-field effect at the hyperfine level of the rovibronic ground state of the^(127)I^(79)Br(X^(1)Σ,v=0,J=0)molecule is computed on the J-I uncoupled basis of|JM_(J)I_(1)M_(1)I_(2)M_(2)>,where J is the molecu...The mixed-field effect at the hyperfine level of the rovibronic ground state of the^(127)I^(79)Br(X^(1)Σ,v=0,J=0)molecule is computed on the J-I uncoupled basis of|JM_(J)I_(1)M_(1)I_(2)M_(2)>,where J is the molecular total angular momentum excluding nuclear spin,M_J is the projection number of J,I_(1) and I_(2) are the nuclear spins of the iodine and bromine atoms,and M_(1) and M_(2) are the projection numbers of I_(1) and I_(2),respectively.When the two applied electric and magnetic fields are parallel,the perturbations are rare and only one perturbation is observed in a relatively large field regime in our computation range.However,when the two fields are off-parallel,the perturbations increase significantly and some sublevels show the Feshbach-like resonance phenomenon.Therefore,such sublevels transit between weak-field seeking and strong-field seeking repeatedly,which can be utilized to enhance or suppress cold molecular collision and chemical reaction rates.Such behavior of the molecular hyperfine structure in the mixed off-parallel fields may also be utilized to construct an electric-field-assisted anti-Helmholtz magnetic trap for cold molecules and to realize evaporative cooling of cold molecules(sub-mK)into the ultracold regime(μK).展开更多
The discrete element method(DEM)and experimental measurements were employed to investigate the influence of impeller rotational speed and paddle angle on the mixing characteristics of two types of non-spherical partic...The discrete element method(DEM)and experimental measurements were employed to investigate the influence of impeller rotational speed and paddle angle on the mixing characteristics of two types of non-spherical particles in a paddle mixer.A close agreement between the simulation and experimental data was observed.By analyzing the motion of particles,it was found that a wide range of diffusion motion occurred when the particles pushed by the paddle blades rolled down the surface of the upper flowing layer of particles in the vessel,which caused the strong circumferential motion of particles,meanwhile promoted the axial movement of particles.The mixing characteristics were analyzed using relative standard deviation(RSD),velocity frequency distribution,diffusivity coefficient and Peclet numbers.The mixing process was accelerated at the rotational speeds of 15,20,and 25 rpm,meanwhile the superior mixing performance was achieved at the paddle angles of 30°and 45°in the study.The fluidity of particles in circumferential direction was higher than that in axial direction.Diffusion was the prevailing mixing mechanism in the current mixing system.展开更多
Specific to problems of the existing round bale wrapping machine in China,such as small application scope and failing to satisfy the wrapping demands of round bales of different specifications,a tumbler-type round bal...Specific to problems of the existing round bale wrapping machine in China,such as small application scope and failing to satisfy the wrapping demands of round bales of different specifications,a tumbler-type round bale wrapping machine based on wrapping silage with stretch film was designed.By theoretical analysis and preliminary experiments of the corresponding wrapping process,revolving speed of tumbler,speed ratio between tumbler and carrier rollers,and pre-load force of stretch film were determined as experimental factors,while wrapping time and consumption of stretch film per unit mass of round bale were determined as evaluation indexes.Furthermore,quadratic regression orthogonal rotational combination experimental design was adopted to carry out the wrapping experiment.The regression models were set up,and influencing rules of experimental factors on evaluation indexes were also analyzed.The optimal parameter combination scheme was revolving speed of tumbler of 31-32 r/min,speed ratio between tumbler and carrier rollers of 2.6,and pre-load force of stretch film of 20-22 N.Under such a circumstance,the corresponding wrapping time required was 37.7-38.9 s and consumption of stretch film per unit mass of round bale was 3.21-3.46 kg/t.The predicted values and the measured values of evaluation indexes basically coincided with each other and the relative error fell below 5%,which indicated that both the optimized regression models acquired through the wrapping experiment and the relevant parameter optimization results were reliable.To guarantee the quality of rice straw silage,the round bale should be wrapped by no less than five layers of stretch films through the utilization of the tumbler-type round bale wrapping machine.The study results could be used as references for research and development of the round bale wrapping machine.展开更多
Aims Drought stress and the degree of drought severity are predicted to rise under highly variable patterns of precipitation due to climate change,while the capacity of trees to cope with drought recovery through phys...Aims Drought stress and the degree of drought severity are predicted to rise under highly variable patterns of precipitation due to climate change,while the capacity of trees to cope with drought recovery through physiological and biochemical adjustment remains unclear.We aimed to examine the coupling of physiology and biochemistry in trees during drought and the following recovery.Methods Potted seedlings of Cinnamomum camphora were grown under well watered conditions prior to the experimental drought stress,which was initiated by withholding water.Seedlings were rewatered following attainment of two drought severities:mild drought(stomatal closure)and moderate drought(ψxylem=−1.5 MPa).We measured leaf-level water potential,gas exchange(photosynthesis and stomatal conductance),abscisic acid(ABA),proline and non-structural carbohydrates(NSCs)concentrations in seedlings of C.camphora during drought and a 4-day recovery.Important Findings We found that drought severity largely determined physiological and biochemical responses and affected the rate of recovery.Stomatal closure occurred at the mild drought stress,accompanied with ABA accumulation in leaves and decline in water potential,while leaf proline accumulation and variable NSC were evident at the moderate drought stress.More severe drought stress led to delayed recovery of gas exchange,but it did not have significant effect on water potential recovery.The relationships of water potential and gas exchange differed during drought stress and post-drought recovery.There was tight coupling between water potential and gas exchange during drought,but not during rewatering due to high ABA accumulation in leaves,thereby delaying recovery of stomatal conductance.Our results demonstrate that ABA could be an important factor in delaying the recovery of stomatal conductance following rewatering and after water potential recovery of C.camphora.Furthermore,greater drought severity had significant impacts on the rate of recovery of tree physiology and biochemistry.展开更多
The objective of this study is to investigate the effectiveness of a multi-parameter intelligent fault diagnosis method based on a modified random forest algorithm(RFNB algorithm),so as to reduce the impact of blockag...The objective of this study is to investigate the effectiveness of a multi-parameter intelligent fault diagnosis method based on a modified random forest algorithm(RFNB algorithm),so as to reduce the impact of blockage fault on the operation of a silage harvester,thus providing a reference for the intelligent control.In brief,the forward speed,cutting speed,engine speed and engine load were selected as the input variables.Then,a random forest(RF)was used to construct a naive Bayes classifier for each node of the decision tree,and finally the RFNB algorithm constituted based on the naive Bayes tree(NBTree).The results revealed that by improving the classification accuracy of a single decision tree,the fault diagnosis accuracy of the entire RF was improved.When the sample data were consistent,the accuracy of the RFNB algorithm was 97.9%,while that of the RF algorithm was only 93.27%.Besides,the performance of RFNB classifiers was significantly better than that of RF classifiers.In conclusion,the RFNB model can accurately identify the fault status of the silage harvester with its good robustness,which provides a new idea for the fault monitoring and early warning of large agricultural rotating machinery in the future.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.12004199,U1810129,52076145,and 11904252).
文摘Hyperfine structures and the field effects of IBr molecule in its rovibronic ground state are theoretically studied by diagonalizing the effective Hamiltonian matrix.Perturbations of high-J levels up to 4 are taken into account when studying the hyperfine sub-levels of the J=0 level,and thus,an 80×80 matrix is constructed and solved.Some of the experimentally absent molecular constants are computed using Dalton program.Our results will be helpful in the experimental investigation of manipulation and further cooling of cold IBr molecules.
基金Project supported by the National Natural Science Foundation of China (Grant No.12004199)。
文摘The mixed-field effect at the hyperfine level of the rovibronic ground state of the^(127)I^(79)Br(X^(1)Σ,v=0,J=0)molecule is computed on the J-I uncoupled basis of|JM_(J)I_(1)M_(1)I_(2)M_(2)>,where J is the molecular total angular momentum excluding nuclear spin,M_J is the projection number of J,I_(1) and I_(2) are the nuclear spins of the iodine and bromine atoms,and M_(1) and M_(2) are the projection numbers of I_(1) and I_(2),respectively.When the two applied electric and magnetic fields are parallel,the perturbations are rare and only one perturbation is observed in a relatively large field regime in our computation range.However,when the two fields are off-parallel,the perturbations increase significantly and some sublevels show the Feshbach-like resonance phenomenon.Therefore,such sublevels transit between weak-field seeking and strong-field seeking repeatedly,which can be utilized to enhance or suppress cold molecular collision and chemical reaction rates.Such behavior of the molecular hyperfine structure in the mixed off-parallel fields may also be utilized to construct an electric-field-assisted anti-Helmholtz magnetic trap for cold molecules and to realize evaporative cooling of cold molecules(sub-mK)into the ultracold regime(μK).
基金supported by National Natural Science Foundation of China(grant No.52205261)the 13th Five Years Key Programs for Science and Technology Development of China(grant No.2016YFD0701300).
文摘The discrete element method(DEM)and experimental measurements were employed to investigate the influence of impeller rotational speed and paddle angle on the mixing characteristics of two types of non-spherical particles in a paddle mixer.A close agreement between the simulation and experimental data was observed.By analyzing the motion of particles,it was found that a wide range of diffusion motion occurred when the particles pushed by the paddle blades rolled down the surface of the upper flowing layer of particles in the vessel,which caused the strong circumferential motion of particles,meanwhile promoted the axial movement of particles.The mixing characteristics were analyzed using relative standard deviation(RSD),velocity frequency distribution,diffusivity coefficient and Peclet numbers.The mixing process was accelerated at the rotational speeds of 15,20,and 25 rpm,meanwhile the superior mixing performance was achieved at the paddle angles of 30°and 45°in the study.The fluidity of particles in circumferential direction was higher than that in axial direction.Diffusion was the prevailing mixing mechanism in the current mixing system.
基金The authors acknowledge that this work was financially supported by the National Natural Science Foundation of China(Grant No.51405076)the 13th Five Years Key Programs for Science and Technology Development of China(Grant No.2016YFD0701300).
文摘Specific to problems of the existing round bale wrapping machine in China,such as small application scope and failing to satisfy the wrapping demands of round bales of different specifications,a tumbler-type round bale wrapping machine based on wrapping silage with stretch film was designed.By theoretical analysis and preliminary experiments of the corresponding wrapping process,revolving speed of tumbler,speed ratio between tumbler and carrier rollers,and pre-load force of stretch film were determined as experimental factors,while wrapping time and consumption of stretch film per unit mass of round bale were determined as evaluation indexes.Furthermore,quadratic regression orthogonal rotational combination experimental design was adopted to carry out the wrapping experiment.The regression models were set up,and influencing rules of experimental factors on evaluation indexes were also analyzed.The optimal parameter combination scheme was revolving speed of tumbler of 31-32 r/min,speed ratio between tumbler and carrier rollers of 2.6,and pre-load force of stretch film of 20-22 N.Under such a circumstance,the corresponding wrapping time required was 37.7-38.9 s and consumption of stretch film per unit mass of round bale was 3.21-3.46 kg/t.The predicted values and the measured values of evaluation indexes basically coincided with each other and the relative error fell below 5%,which indicated that both the optimized regression models acquired through the wrapping experiment and the relevant parameter optimization results were reliable.To guarantee the quality of rice straw silage,the round bale should be wrapped by no less than five layers of stretch films through the utilization of the tumbler-type round bale wrapping machine.The study results could be used as references for research and development of the round bale wrapping machine.
基金supported by grants from the National Natural Science Foundation of China(31600483,31760111,31901091)the Outstanding Young Scholar of Jiangxi Science and Technology Innovation(20192BCBL23016)the Jiangxi Provincial Department of Education(GJJ190945).
文摘Aims Drought stress and the degree of drought severity are predicted to rise under highly variable patterns of precipitation due to climate change,while the capacity of trees to cope with drought recovery through physiological and biochemical adjustment remains unclear.We aimed to examine the coupling of physiology and biochemistry in trees during drought and the following recovery.Methods Potted seedlings of Cinnamomum camphora were grown under well watered conditions prior to the experimental drought stress,which was initiated by withholding water.Seedlings were rewatered following attainment of two drought severities:mild drought(stomatal closure)and moderate drought(ψxylem=−1.5 MPa).We measured leaf-level water potential,gas exchange(photosynthesis and stomatal conductance),abscisic acid(ABA),proline and non-structural carbohydrates(NSCs)concentrations in seedlings of C.camphora during drought and a 4-day recovery.Important Findings We found that drought severity largely determined physiological and biochemical responses and affected the rate of recovery.Stomatal closure occurred at the mild drought stress,accompanied with ABA accumulation in leaves and decline in water potential,while leaf proline accumulation and variable NSC were evident at the moderate drought stress.More severe drought stress led to delayed recovery of gas exchange,but it did not have significant effect on water potential recovery.The relationships of water potential and gas exchange differed during drought stress and post-drought recovery.There was tight coupling between water potential and gas exchange during drought,but not during rewatering due to high ABA accumulation in leaves,thereby delaying recovery of stomatal conductance.Our results demonstrate that ABA could be an important factor in delaying the recovery of stomatal conductance following rewatering and after water potential recovery of C.camphora.Furthermore,greater drought severity had significant impacts on the rate of recovery of tree physiology and biochemistry.
基金National Key R&D Program of China(2016YFD0701301)。
文摘The objective of this study is to investigate the effectiveness of a multi-parameter intelligent fault diagnosis method based on a modified random forest algorithm(RFNB algorithm),so as to reduce the impact of blockage fault on the operation of a silage harvester,thus providing a reference for the intelligent control.In brief,the forward speed,cutting speed,engine speed and engine load were selected as the input variables.Then,a random forest(RF)was used to construct a naive Bayes classifier for each node of the decision tree,and finally the RFNB algorithm constituted based on the naive Bayes tree(NBTree).The results revealed that by improving the classification accuracy of a single decision tree,the fault diagnosis accuracy of the entire RF was improved.When the sample data were consistent,the accuracy of the RFNB algorithm was 97.9%,while that of the RF algorithm was only 93.27%.Besides,the performance of RFNB classifiers was significantly better than that of RF classifiers.In conclusion,the RFNB model can accurately identify the fault status of the silage harvester with its good robustness,which provides a new idea for the fault monitoring and early warning of large agricultural rotating machinery in the future.
