The age-structure of natural population of Zoysia japonica in Xiuyan County of Liaoning Province was studied by generational method. The results showed that the highest tiller age class was three, but 1st age class ti...The age-structure of natural population of Zoysia japonica in Xiuyan County of Liaoning Province was studied by generational method. The results showed that the highest tiller age class was three, but 1st age class tillers held dominant posi-tion with proportions over 95% in each month during the growing seasons. The 2nd age class and 3rd age class tillers were minority in the population. So Z. japonica population was an expanding population. The zero age class buds on the rhizomes were dominant in buds age structures. The proportion of buds to tillers on quantity in each month was about 30% to 40% and reached the highest at the end of September. The increasing of buds proportion before dormancy guaranteed the quantity of tillers in the next spring. The biomass of 1st age class tillers changed with time. The biomass kept increasing from April to July and reached the highest at the end of July and then decreased.展开更多
An investigation of electronic property and high pressure phase stability of SmN has been conducted using first principles calculations based on density functional theory. The elec- tronic properties of Stun show a st...An investigation of electronic property and high pressure phase stability of SmN has been conducted using first principles calculations based on density functional theory. The elec- tronic properties of Stun show a striking feature of a half metal, the majority-spin electrons are metallic and the minority-spin electrons are semiconducting. It was found that Stun undergoes a pressure-induced phase transition from NaCl-type （B1） to CsCl-type structure （B2） at 117 GPa. The elastic constants of Stun satisfy Born conditions at ambient pressure, indicating that B1 phase of SmN is mechanically stable at 0 GPa. The result of phonon spectra shows that B1 structure is dynamically stable at ambient pressure, which agrees with the conclusion derived from the elastic constants.展开更多
In order to improve the quality of web search,a new query expansion method by choosing meaningful structure data from a domain database is proposed.It categories attributes into three different classes,named as concep...In order to improve the quality of web search,a new query expansion method by choosing meaningful structure data from a domain database is proposed.It categories attributes into three different classes,named as concept attribute,context attribute and meaningless attribute,according to their semantic features which are document frequency features and distinguishing capability features.It also defines the semantic relevance between two attributes when they have correlations in the database.Then it proposes trie-bitmap structure and pair pointer tables to implement efficient algorithms for discovering attribute semantic feature and detecting their semantic relevances.By using semantic attributes and their semantic relevances,expansion words can be generated and embedded into a vector space model with interpolation parameters.The experiments use an IMDB movie database and real texts collections to evaluate the proposed method by comparing its performance with a classical vector space model.The results show that the proposed method can improve text search efficiently and also improve both semantic features and semantic relevances with good separation capabilities.展开更多
Considering the problems of classical structure parameters that existed in the study of quantitative structure activity relationship (QSAR). Two new groups of autocorrelation topological indexes V(t), E(t), (P(t)) and...Considering the problems of classical structure parameters that existed in the study of quantitative structure activity relationship (QSAR). Two new groups of autocorrelation topological indexes V(t), E(t), (P(t)) and A(t), B(t), C(t), D(t) were developed on the basis of molecular topology and autocorrelation function in mathematics. The first group were obtained from Van der Waals volume, electronegativity and topological vertex degree;and the second group were obtained from the different combination of topological vertex degree.Corresponding softwares of ATIJP and ATITP have been developed for calculating these two new groups of indexes. Better results have been obtained from the application of these indexes in QSAR study.展开更多
Numerical simulations were performed on flow and heat transfer performances of heat exchangers having six helical baffles of different baffle shapes and assembly configurations, i.e., two trisection baffle schemes, tw...Numerical simulations were performed on flow and heat transfer performances of heat exchangers having six helical baffles of different baffle shapes and assembly configurations, i.e., two trisection baffle schemes, two quadrant baffle schemes, and two continuous helical baffle schemes. The temperature contour or the pressure contour and velocity contour plots with superimposed velocity vectors on meridian, transverse and unfolded concentric hexagonal slices are presented to obtain a full angular view. For the six helix baffled heat exchangers,the different patterns of the single vortex secondary flow and the shortcut leakage flow were depicted as well as the heat transfer properties were compared. The results show that the optimum scheme among the six configurations is a circumferential overlap trisection helix baffled heat exchanger with a baffle incline angle of 20°(20°TCO) scheme with an anti-shortcut baffle structure, which exhibits the second highest pressure dropΔpo, the highest overall heat transfer coefficient K, shell-side heat transfer coefficient hoand shell-side average comprehensive index ho/Δpo.展开更多
A new type of highly nonlinear photonic bandgap fiber with modified honeycomb lattice is brought forward. Based on full-vector plane-wave method, the structure of bandgaps and the distributions of fundamental mode fie...A new type of highly nonlinear photonic bandgap fiber with modified honeycomb lattice is brought forward. Based on full-vector plane-wave method, the structure of bandgaps and the distributions of fundamental mode field are analyzed. Then its nonlinear coefficient is calculated, and the effect of each structural pa- rameter on the nonlinear coefficient is discussed. At last, considering many factors synthetically, we make some optimization design of the structural parameters. It can be concluded that this new type of photonic bandgap fiber can gain the nonlinear coefficient of 30 W^-1 km^-1.展开更多
Random dynamic responses caused by the uncertainty of structural parameters of the coupled train-ballasted track-subgrade system under train loading can pose safety concerns to the train operation.This paper introduce...Random dynamic responses caused by the uncertainty of structural parameters of the coupled train-ballasted track-subgrade system under train loading can pose safety concerns to the train operation.This paper introduced a computational model for analyzing probabilistic dynamic responses of three-dimensional(3D)coupled train-ballasted track-subgrade system(TBTSS),where the coupling effects of uncertain rail irregularities,stiffness and damping properties of ballast and subgrade layers were simultaneously considered.The number theoretical method(NTM)was employed to design discrete points for the multi-dimensional stochastic parameters.The time-histories of stochastic dynamic vibrations of the TBSS with systematically uncertain structural parameters were calculated accurately and efficiently by employing the probability density evolution method(PDEM).The model-predicted results were consistent with those by the Monte Carlo simulation method.A sensitivity study was performed to assess the relative importance of those uncertain structural parameters,based on which a case study was presented to explore the stochastic probability evolution mechanism of such train-ballasted track-subgrade system.展开更多
By means of HAAKE RS105L cone and plate rheometer the concentrated solution, including viscous flow activation energy, non-Newtonian index, structural viscosity index and relaxation time of the PMIA solution were stud...By means of HAAKE RS105L cone and plate rheometer the concentrated solution, including viscous flow activation energy, non-Newtonian index, structural viscosity index and relaxation time of the PMIA solution were studied. The effect of concentration and temperature of the solution and molecular weight of the polymer on its non-Newtonian behavior was investigated. The results showed that PMIA concentrated solution prepared via low temperature condensation was of non-Newtonian fluid. With the decrease of temperature, increase of solution concentration and PMIA molecular weight, the deviation of the solution from Newtonian behavior decreased. The molecular weight of the polymer and the concentration of the solution affected the non- Newtonian behavior mete intensively.展开更多
By using the further extended tanh method [Phys. Lett. A 307 （2003） 269; Chaos, Solitons ＆ Fractals 17 （2003） 669] to the Broer-Kaup system with variable coefficients, abundant new soliton-like solutions and mult...By using the further extended tanh method [Phys. Lett. A 307 （2003） 269; Chaos, Solitons ＆ Fractals 17 （2003） 669] to the Broer-Kaup system with variable coefficients, abundant new soliton-like solutions and multl-solitonlike solutions are derived. Based on the derived multi-soliton-like solutions which contain arbitrary functions, some interesting multi-soliton structures are revealed.展开更多
Effects of Zn/P ratio on the structures and properties of glasses with the general composition of （80-x）ZnO-20Fe2O3-xP2O5 （x=40, 45, 50, 55, 60） （molar fraction, %） were investigated. Glass structure was measure...Effects of Zn/P ratio on the structures and properties of glasses with the general composition of （80-x）ZnO-20Fe2O3-xP2O5 （x=40, 45, 50, 55, 60） （molar fraction, %） were investigated. Glass structure was measured by infrared absorption spectrum. Glass density （/9） was measured by the Archimedes method. Coefficients of thermal expansion （a） and characterization temperature were obtained by a dilatometer. Water durability of each glass was estimated from the dissolution rate （DR）in water at 90 ℃ for 24 h. With increasing Zn/P ratio, water durability of zinc-iron phosphate glasses increases dramatically without large increase in the characterization temperature. （80-x）ZnO-20Fe2O3-xP2O5 glasses with 0.3≤Zn/P≤0.5 are suit for low-to-mid temperature sealing application for substrates with a〈8.0× 10^-6℃^-1.展开更多
基金This study was supported by the NKBRSF (G1999043407-1) Knowledge Innovation Program of the Chinese Academy of Sciences (KZCX2-406+3 种基金 SCXZD0101) NKTRDP (2001BA510B-07 2002BA516A20) and Education Committee Projects of Liaong Province (990121400
文摘The age-structure of natural population of Zoysia japonica in Xiuyan County of Liaoning Province was studied by generational method. The results showed that the highest tiller age class was three, but 1st age class tillers held dominant posi-tion with proportions over 95% in each month during the growing seasons. The 2nd age class and 3rd age class tillers were minority in the population. So Z. japonica population was an expanding population. The zero age class buds on the rhizomes were dominant in buds age structures. The proportion of buds to tillers on quantity in each month was about 30% to 40% and reached the highest at the end of September. The increasing of buds proportion before dormancy guaranteed the quantity of tillers in the next spring. The biomass of 1st age class tillers changed with time. The biomass kept increasing from April to July and reached the highest at the end of July and then decreased.
文摘An investigation of electronic property and high pressure phase stability of SmN has been conducted using first principles calculations based on density functional theory. The elec- tronic properties of Stun show a striking feature of a half metal, the majority-spin electrons are metallic and the minority-spin electrons are semiconducting. It was found that Stun undergoes a pressure-induced phase transition from NaCl-type （B1） to CsCl-type structure （B2） at 117 GPa. The elastic constants of Stun satisfy Born conditions at ambient pressure, indicating that B1 phase of SmN is mechanically stable at 0 GPa. The result of phonon spectra shows that B1 structure is dynamically stable at ambient pressure, which agrees with the conclusion derived from the elastic constants.
基金Program for New Century Excellent Talents in University(No.NCET-06-0290)the National Natural Science Foundation of China(No.60503036)the Fok Ying Tong Education Foundation Award(No.104027)
文摘In order to improve the quality of web search,a new query expansion method by choosing meaningful structure data from a domain database is proposed.It categories attributes into three different classes,named as concept attribute,context attribute and meaningless attribute,according to their semantic features which are document frequency features and distinguishing capability features.It also defines the semantic relevance between two attributes when they have correlations in the database.Then it proposes trie-bitmap structure and pair pointer tables to implement efficient algorithms for discovering attribute semantic feature and detecting their semantic relevances.By using semantic attributes and their semantic relevances,expansion words can be generated and embedded into a vector space model with interpolation parameters.The experiments use an IMDB movie database and real texts collections to evaluate the proposed method by comparing its performance with a classical vector space model.The results show that the proposed method can improve text search efficiently and also improve both semantic features and semantic relevances with good separation capabilities.
文摘Considering the problems of classical structure parameters that existed in the study of quantitative structure activity relationship (QSAR). Two new groups of autocorrelation topological indexes V(t), E(t), (P(t)) and A(t), B(t), C(t), D(t) were developed on the basis of molecular topology and autocorrelation function in mathematics. The first group were obtained from Van der Waals volume, electronegativity and topological vertex degree;and the second group were obtained from the different combination of topological vertex degree.Corresponding softwares of ATIJP and ATITP have been developed for calculating these two new groups of indexes. Better results have been obtained from the application of these indexes in QSAR study.
基金Supported by the National Natural Science Foundation of China(50976022,51276035)the Provincial Science and Technology Innovation and Transformation of Achievements of Special Fund Project of Jiangsu Province(BY2011155)
文摘Numerical simulations were performed on flow and heat transfer performances of heat exchangers having six helical baffles of different baffle shapes and assembly configurations, i.e., two trisection baffle schemes, two quadrant baffle schemes, and two continuous helical baffle schemes. The temperature contour or the pressure contour and velocity contour plots with superimposed velocity vectors on meridian, transverse and unfolded concentric hexagonal slices are presented to obtain a full angular view. For the six helix baffled heat exchangers,the different patterns of the single vortex secondary flow and the shortcut leakage flow were depicted as well as the heat transfer properties were compared. The results show that the optimum scheme among the six configurations is a circumferential overlap trisection helix baffled heat exchanger with a baffle incline angle of 20°(20°TCO) scheme with an anti-shortcut baffle structure, which exhibits the second highest pressure dropΔpo, the highest overall heat transfer coefficient K, shell-side heat transfer coefficient hoand shell-side average comprehensive index ho/Δpo.
基金Supported by the National 863 Project of China (2004AA31G200) .
文摘A new type of highly nonlinear photonic bandgap fiber with modified honeycomb lattice is brought forward. Based on full-vector plane-wave method, the structure of bandgaps and the distributions of fundamental mode field are analyzed. Then its nonlinear coefficient is calculated, and the effect of each structural pa- rameter on the nonlinear coefficient is discussed. At last, considering many factors synthetically, we make some optimization design of the structural parameters. It can be concluded that this new type of photonic bandgap fiber can gain the nonlinear coefficient of 30 W^-1 km^-1.
基金Projects(51708558,51878673,U1734208,52078485,U1934217,U1934209)supported by the National Natural Science Foundation of ChinaProject(2020JJ5740)supported by the Natural Science Foundation of Hunan Province,China+1 种基金Project(KF2020-03)supported by the Key Open Fund of State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures,ChinaProject(2020-Special-02)supported by the Science and Technology Research and Development Program of China Railway Group Limited。
文摘Random dynamic responses caused by the uncertainty of structural parameters of the coupled train-ballasted track-subgrade system under train loading can pose safety concerns to the train operation.This paper introduced a computational model for analyzing probabilistic dynamic responses of three-dimensional(3D)coupled train-ballasted track-subgrade system(TBTSS),where the coupling effects of uncertain rail irregularities,stiffness and damping properties of ballast and subgrade layers were simultaneously considered.The number theoretical method(NTM)was employed to design discrete points for the multi-dimensional stochastic parameters.The time-histories of stochastic dynamic vibrations of the TBSS with systematically uncertain structural parameters were calculated accurately and efficiently by employing the probability density evolution method(PDEM).The model-predicted results were consistent with those by the Monte Carlo simulation method.A sensitivity study was performed to assess the relative importance of those uncertain structural parameters,based on which a case study was presented to explore the stochastic probability evolution mechanism of such train-ballasted track-subgrade system.
文摘By means of HAAKE RS105L cone and plate rheometer the concentrated solution, including viscous flow activation energy, non-Newtonian index, structural viscosity index and relaxation time of the PMIA solution were studied. The effect of concentration and temperature of the solution and molecular weight of the polymer on its non-Newtonian behavior was investigated. The results showed that PMIA concentrated solution prepared via low temperature condensation was of non-Newtonian fluid. With the decrease of temperature, increase of solution concentration and PMIA molecular weight, the deviation of the solution from Newtonian behavior decreased. The molecular weight of the polymer and the concentration of the solution affected the non- Newtonian behavior mete intensively.
基金中国博士后科学基金，National Key Basic Research Project of China
文摘By using the further extended tanh method [Phys. Lett. A 307 （2003） 269; Chaos, Solitons ＆ Fractals 17 （2003） 669] to the Broer-Kaup system with variable coefficients, abundant new soliton-like solutions and multl-solitonlike solutions are derived. Based on the derived multi-soliton-like solutions which contain arbitrary functions, some interesting multi-soliton structures are revealed.
基金Project(7602110340) supported by the Postdoctoral Science Foundation of Central South University, ChinaProject(721500277)supported by the Fundamental Research Funds for the Central Universities of China
文摘Effects of Zn/P ratio on the structures and properties of glasses with the general composition of （80-x）ZnO-20Fe2O3-xP2O5 （x=40, 45, 50, 55, 60） （molar fraction, %） were investigated. Glass structure was measured by infrared absorption spectrum. Glass density （/9） was measured by the Archimedes method. Coefficients of thermal expansion （a） and characterization temperature were obtained by a dilatometer. Water durability of each glass was estimated from the dissolution rate （DR）in water at 90 ℃ for 24 h. With increasing Zn/P ratio, water durability of zinc-iron phosphate glasses increases dramatically without large increase in the characterization temperature. （80-x）ZnO-20Fe2O3-xP2O5 glasses with 0.3≤Zn/P≤0.5 are suit for low-to-mid temperature sealing application for substrates with a〈8.0× 10^-6℃^-1.
