Factors that affect highway-related crash frequency and injury severity vary across observations. Using a methodology that does not account nor correct for heterogeneity in observed and unobserved crash factors across...Factors that affect highway-related crash frequency and injury severity vary across observations. Using a methodology that does not account nor correct for heterogeneity in observed and unobserved crash factors across highway segments may lead to biased and inconsistent estimated coefficients, thus resulting in erroneous inferences. The present paper demonstrates the use of random-parameters models to facilitate and enhance how crash factors affect crash frequency and injury severity along a highway segment. The results indicate that a unit increase in the presence of stop sign along a highway segment reduces crash frequency by 2.471 for 87.24% of the roadway segments. For the remaining 12.76% of the roadway segments, crash frequency is increased by the same margin. Using the random-parameters multinomial logit model, the result indicates that, for 90.89% of the observations, the presence of a stop sign on a highway segment increases the probability of the injury outcome. For 9.11% of the observations, the presence of a stop sign on a highway segment reduces the probability of the injury outcome, and the marginal effect value across observations is 0.0017. Vertical grades greater than 5% increase crash frequency for 58.46% of the highway segments, and decrease for 41.54% of the highway segments by 0.121 for one unit increase in vertical grades.展开更多
In order to more accurately predict the contact fatigue life of rolling bearing, a prediction method of fatigue life of rolling bearing is proposed based on elastohydrodynamic lubrication （EHL）, the 3-paameter Weibu...In order to more accurately predict the contact fatigue life of rolling bearing, a prediction method of fatigue life of rolling bearing is proposed based on elastohydrodynamic lubrication （EHL）, the 3-paameter Weibull distribution ad fatigue strength. First,the contact stress considering elliptical EHL is obtained by mapping film pressure onto the Hertz zone. Then,the basic strength model of rolling bearing based on the 3-parameter Weibull distribution is deduced by the series connection reliability theory. Considering the effect of the type of stress, variation of shape and fuctuation of load, the mathematical models of the 尸 -tS-TV curve of the minimum life and the characteristic life for rolling bearing are established, respectively, and thus the prediction model of fatigue life of rolling bearing based on the 3-paameter Weibull distribution and fatigue strength is further deduced. Finally, the contact fatigue life obtained by the proposed method ad the latest international standard （IS0281： 2007） about the fatigue life prediction of rolling bearing are compared with those obtained by the statistical method. Results show that the proposed prediction method is effective and its relative error is smaier than that of the latest international standard （IS0281： 2007） with reliability R 〉 0. 93.展开更多
Using the mechanical principle, the theory of modern geometry and advanced calculus, Hamiltonian mechanics was generalized to Kahler manifolds, and the Hamiltonian mechanics on Kahler manifolds was established. Then t...Using the mechanical principle, the theory of modern geometry and advanced calculus, Hamiltonian mechanics was generalized to Kahler manifolds, and the Hamiltonian mechanics on Kahler manifolds was established. Then the complex mathematical aspect of Hamiltonian vector field and Hamilton＇s equations was obtained, and so on.展开更多
Based on the strain formulation of the quasi-conforming finite element, displacement functions are constructed which have definite physical meaning, and a conclusion can be obtained that the coefficients of the consta...Based on the strain formulation of the quasi-conforming finite element, displacement functions are constructed which have definite physical meaning, and a conclusion can be obtained that the coefficients of the constant and the linear strain are uniquely determined, and the quasi-conforming finite element method is convergent to constant strain. There are different methods for constructing the rigid displacement items, and different methods correspond to different order node errors, and this is different from ordinary displacement method finite element.展开更多
In this paper, we consider two extended systems. When using them for the two parameter bifurcation problems, the simple bifurcation point with regard to lambda on turn into the simple turning point with. regard to mu....In this paper, we consider two extended systems. When using them for the two parameter bifurcation problems, the simple bifurcation point with regard to lambda on turn into the simple turning point with. regard to mu. Simple high orde bifurcation point is first studied without using the symmetry condition.展开更多
The adsorption of O and N atoms on the Ni（311） surface was investigated by the 5-parameter Morse potential（5-MP） method in detail. For the O-Ni（311） system, there are three surface adsorption states and the fcc-...The adsorption of O and N atoms on the Ni（311） surface was investigated by the 5-parameter Morse potential（5-MP） method in detail. For the O-Ni（311） system, there are three surface adsorption states and the fcc-3-fold site is metastable; the frequency of 75 meV[67 meV in high resolution electron energy loss spectroscopy（HREELS） experiment] is attributed to the vibration at the hcp-3-fold site. For the N-Ni（311） system, however, there are only two surface adsorption states（no surface adsorption state was calculated atfcc-3-fold site）. In addition, subsurface states were predicted and all critical characteristics were obtained for the two systems.展开更多
Knowledge of genetic diversity and barcoding of yam is lacking in Enugu and Ebonyi States of southern Nigeria. Therefore, DNA barcoding was used to facilitate identification and biodiversity studies of yam species fro...Knowledge of genetic diversity and barcoding of yam is lacking in Enugu and Ebonyi States of southern Nigeria. Therefore, DNA barcoding was used to facilitate identification and biodiversity studies of yam species from Southern Nigeria. Seventy five yam accessions were collected from Enugu and Ebonyi States, including International Institute of Tropical Agriculture for DNA extraction and amplification using a chloroplast DNA (cpDNA) ribulose-1,5-bisphosphate carboxylase (rbcL) marker. There was high level of similarity among the accessions and presence of 534 conserved and 7 variable sites. A transversional mutation of G/T at a consensus position of 335 was identified followed by transitions at 362 (A/G), 368 (A/G), 371 (C/T) and 391 (C/T) within the accessions. Phylogeny resolved the yam accessions into ten major groups with their bootstrap values ranging from 0 - 100. Phylogenetic diversity was highest in group X, followed by VII, VI and IX. The inter-group genetic distance based on Kimura 2-parameter model ranged from 0.5000 ± 0.4770 - 5.0560 ± 2.5760, while the intra-group had 0.5250 ± 0.5000 - 2.0103 ± 1.2579. The mean genetic diversity within the entire population was 0.7970 ± 0.06910. BLAST analysis of total bit score, query coverage, and percentage identity were in the ranges of 411 - 1011, 99% - 100% and 97% - 100%, respectively. However, the rbcL could not resolve the yam accessions well following the comparative assessment of some discrepancies in the detected number of species from phylogenetic groupings, genetic diversity indices and NCBI BLAST hits, thereby, exposing the inefficiency of this marker in discriminating the yam accessions. It was demonstrated that rbcL is not an effective marker;therefore, it should not be recommended as a standard-alone marker of choice for DNA barcoding of yam accessions, especially, when accurate identification, discrimination and estimation of genetic diversity of this vital crop are of paramount importance for crop improvement and germplasm conservation.展开更多
Hydrologic frequency analysis plays an important role in coastal and ocean engineering for structural design and disaster prevention in coastal areas. This paper proposes a Nonlinear Least Squares Method (NLSM), which...Hydrologic frequency analysis plays an important role in coastal and ocean engineering for structural design and disaster prevention in coastal areas. This paper proposes a Nonlinear Least Squares Method (NLSM), which estimates the three unknown parameters of the Weibull distribution simultaneously by an iteration method. Statistical test shows that the NLSM fits each data sample well. The effects of different parameter-fitting methods, distribution models, and threshold values are also discussed in the statistical analysis of storm set-down elevation. The best-fitting probability distribution is given and the corresponding return values are estimated for engineering design.展开更多
Data on time between complete power outages, Time between Failure (TBF) in Uyo were considered. Trend test and serial correlation test were conducted graphically for the data. The tests proved that the data were ident...Data on time between complete power outages, Time between Failure (TBF) in Uyo were considered. Trend test and serial correlation test were conducted graphically for the data. The tests proved that the data were identically and independently distributed (iid). Summary statistics of the data showed that complete power outage occurred 416 times between the year 2014 and 2018. The maximum likelihood estimation method was used to estimate the parameters of Weibull 2-parameter, Normal, Lognormal 2-parameter and exponential distributions. The values of Kolmogorov-Smirnov, Anderson Darling and Chi-Square statistics were used to determine the best fit distributions. A model</span></span><span><span><span style="font-family:""> </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">for the computation of reliability of electric power was then proposed</span></span></span><span style="font-family:Verdana;">.展开更多
A simpler definition for a class of 2-parameter quantum groups associated to semisimple Lie algebras is given in terms of Euler form.Their positive parts turn out to be 2-cocycle deformations of each other under some ...A simpler definition for a class of 2-parameter quantum groups associated to semisimple Lie algebras is given in terms of Euler form.Their positive parts turn out to be 2-cocycle deformations of each other under some conditions.An operator realization of the positive part is given.展开更多
The convex PBW-type Lyndon basis for two-parameter quantum group U_(r,s)(F_(4))is given.Assume thatrs^(-1)is a primitive l-th root of unity with l odd,then the restricted quantum group u_(r,s)(F_(4))as a quotient of U...The convex PBW-type Lyndon basis for two-parameter quantum group U_(r,s)(F_(4))is given.Assume thatrs^(-1)is a primitive l-th root of unity with l odd,then the restricted quantum group u_(r,s)(F_(4))as a quotient of U_(r,s)(F_(4))is pointed,and of a Drinfel’d double structure under a certain condition.All of Hopf isomorphisms of u_(r,s)(F_(4))are determined,and the necessary and sufficient condition for u_(r,s)(F_(4))to be a ribbon Hopf algebra is singled out by describing the left and right integrals.展开更多
This work presents the subtraction procedure and the Regge cut in the logarithmic Regge pole approach.The subtraction mechanism leads to the same asymptotic behavior as previously obtained in the non-subtraction case....This work presents the subtraction procedure and the Regge cut in the logarithmic Regge pole approach.The subtraction mechanism leads to the same asymptotic behavior as previously obtained in the non-subtraction case.The Regge cut,in contrast,introduces a clear role to the non-leading contributions for the asymptotic behavior of the total cross-section.From these results,some simple parameterization is introduced to fit the experimental data for the proton-proton and antiproton-proton total cross-section above some minimum value up to the cosmic-ray.The fit parameters obtained are used to present predictions for the ρ(s)-parameter as well as to the elastic slope B(s)at high energies.展开更多
文摘Factors that affect highway-related crash frequency and injury severity vary across observations. Using a methodology that does not account nor correct for heterogeneity in observed and unobserved crash factors across highway segments may lead to biased and inconsistent estimated coefficients, thus resulting in erroneous inferences. The present paper demonstrates the use of random-parameters models to facilitate and enhance how crash factors affect crash frequency and injury severity along a highway segment. The results indicate that a unit increase in the presence of stop sign along a highway segment reduces crash frequency by 2.471 for 87.24% of the roadway segments. For the remaining 12.76% of the roadway segments, crash frequency is increased by the same margin. Using the random-parameters multinomial logit model, the result indicates that, for 90.89% of the observations, the presence of a stop sign on a highway segment increases the probability of the injury outcome. For 9.11% of the observations, the presence of a stop sign on a highway segment reduces the probability of the injury outcome, and the marginal effect value across observations is 0.0017. Vertical grades greater than 5% increase crash frequency for 58.46% of the highway segments, and decrease for 41.54% of the highway segments by 0.121 for one unit increase in vertical grades.
基金The National Defense Advance Research Program(No.81302XXX)
文摘In order to more accurately predict the contact fatigue life of rolling bearing, a prediction method of fatigue life of rolling bearing is proposed based on elastohydrodynamic lubrication （EHL）, the 3-paameter Weibull distribution ad fatigue strength. First,the contact stress considering elliptical EHL is obtained by mapping film pressure onto the Hertz zone. Then,the basic strength model of rolling bearing based on the 3-parameter Weibull distribution is deduced by the series connection reliability theory. Considering the effect of the type of stress, variation of shape and fuctuation of load, the mathematical models of the 尸 -tS-TV curve of the minimum life and the characteristic life for rolling bearing are established, respectively, and thus the prediction model of fatigue life of rolling bearing based on the 3-paameter Weibull distribution and fatigue strength is further deduced. Finally, the contact fatigue life obtained by the proposed method ad the latest international standard （IS0281： 2007） about the fatigue life prediction of rolling bearing are compared with those obtained by the statistical method. Results show that the proposed prediction method is effective and its relative error is smaier than that of the latest international standard （IS0281： 2007） with reliability R 〉 0. 93.
文摘Using the mechanical principle, the theory of modern geometry and advanced calculus, Hamiltonian mechanics was generalized to Kahler manifolds, and the Hamiltonian mechanics on Kahler manifolds was established. Then the complex mathematical aspect of Hamiltonian vector field and Hamilton＇s equations was obtained, and so on.
文摘Based on the strain formulation of the quasi-conforming finite element, displacement functions are constructed which have definite physical meaning, and a conclusion can be obtained that the coefficients of the constant and the linear strain are uniquely determined, and the quasi-conforming finite element method is convergent to constant strain. There are different methods for constructing the rigid displacement items, and different methods correspond to different order node errors, and this is different from ordinary displacement method finite element.
文摘In this paper, we consider two extended systems. When using them for the two parameter bifurcation problems, the simple bifurcation point with regard to lambda on turn into the simple turning point with. regard to mu. Simple high orde bifurcation point is first studied without using the symmetry condition.
基金Supported by the Natural Science Foundation of Shandong Province, China(No.Y2006B29).
文摘The adsorption of O and N atoms on the Ni（311） surface was investigated by the 5-parameter Morse potential（5-MP） method in detail. For the O-Ni（311） system, there are three surface adsorption states and the fcc-3-fold site is metastable; the frequency of 75 meV[67 meV in high resolution electron energy loss spectroscopy（HREELS） experiment] is attributed to the vibration at the hcp-3-fold site. For the N-Ni（311） system, however, there are only two surface adsorption states（no surface adsorption state was calculated atfcc-3-fold site）. In addition, subsurface states were predicted and all critical characteristics were obtained for the two systems.
文摘Knowledge of genetic diversity and barcoding of yam is lacking in Enugu and Ebonyi States of southern Nigeria. Therefore, DNA barcoding was used to facilitate identification and biodiversity studies of yam species from Southern Nigeria. Seventy five yam accessions were collected from Enugu and Ebonyi States, including International Institute of Tropical Agriculture for DNA extraction and amplification using a chloroplast DNA (cpDNA) ribulose-1,5-bisphosphate carboxylase (rbcL) marker. There was high level of similarity among the accessions and presence of 534 conserved and 7 variable sites. A transversional mutation of G/T at a consensus position of 335 was identified followed by transitions at 362 (A/G), 368 (A/G), 371 (C/T) and 391 (C/T) within the accessions. Phylogeny resolved the yam accessions into ten major groups with their bootstrap values ranging from 0 - 100. Phylogenetic diversity was highest in group X, followed by VII, VI and IX. The inter-group genetic distance based on Kimura 2-parameter model ranged from 0.5000 ± 0.4770 - 5.0560 ± 2.5760, while the intra-group had 0.5250 ± 0.5000 - 2.0103 ± 1.2579. The mean genetic diversity within the entire population was 0.7970 ± 0.06910. BLAST analysis of total bit score, query coverage, and percentage identity were in the ranges of 411 - 1011, 99% - 100% and 97% - 100%, respectively. However, the rbcL could not resolve the yam accessions well following the comparative assessment of some discrepancies in the detected number of species from phylogenetic groupings, genetic diversity indices and NCBI BLAST hits, thereby, exposing the inefficiency of this marker in discriminating the yam accessions. It was demonstrated that rbcL is not an effective marker;therefore, it should not be recommended as a standard-alone marker of choice for DNA barcoding of yam accessions, especially, when accurate identification, discrimination and estimation of genetic diversity of this vital crop are of paramount importance for crop improvement and germplasm conservation.
基金supported by the 10th Five-Year Plan Key Project of China and the National Science Foundation of China(grant No.40076028).
文摘Hydrologic frequency analysis plays an important role in coastal and ocean engineering for structural design and disaster prevention in coastal areas. This paper proposes a Nonlinear Least Squares Method (NLSM), which estimates the three unknown parameters of the Weibull distribution simultaneously by an iteration method. Statistical test shows that the NLSM fits each data sample well. The effects of different parameter-fitting methods, distribution models, and threshold values are also discussed in the statistical analysis of storm set-down elevation. The best-fitting probability distribution is given and the corresponding return values are estimated for engineering design.
文摘Data on time between complete power outages, Time between Failure (TBF) in Uyo were considered. Trend test and serial correlation test were conducted graphically for the data. The tests proved that the data were identically and independently distributed (iid). Summary statistics of the data showed that complete power outage occurred 416 times between the year 2014 and 2018. The maximum likelihood estimation method was used to estimate the parameters of Weibull 2-parameter, Normal, Lognormal 2-parameter and exponential distributions. The values of Kolmogorov-Smirnov, Anderson Darling and Chi-Square statistics were used to determine the best fit distributions. A model</span></span><span><span><span style="font-family:""> </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">for the computation of reliability of electric power was then proposed</span></span></span><span style="font-family:Verdana;">.
基金the National Natural Science Foundation of China(Grant Nos.10431040,10728102)the TRAPOYT,the FUDP and the Priority Academic Discipline from the MOE of China,the SRSTP from the STCSM,the Shanghai Priority Academic Discipline from the SMEC
文摘A simpler definition for a class of 2-parameter quantum groups associated to semisimple Lie algebras is given in terms of Euler form.Their positive parts turn out to be 2-cocycle deformations of each other under some conditions.An operator realization of the positive part is given.
基金Nai Hong Hu is supported by the NNSF of China(Grant Nos.12171155,12071094)in part by Science and Technology Commission of Shanghai Municipality(Grant No.22DZ2229014)。
文摘The convex PBW-type Lyndon basis for two-parameter quantum group U_(r,s)(F_(4))is given.Assume thatrs^(-1)is a primitive l-th root of unity with l odd,then the restricted quantum group u_(r,s)(F_(4))as a quotient of U_(r,s)(F_(4))is pointed,and of a Drinfel’d double structure under a certain condition.All of Hopf isomorphisms of u_(r,s)(F_(4))are determined,and the necessary and sufficient condition for u_(r,s)(F_(4))to be a ribbon Hopf algebra is singled out by describing the left and right integrals.
文摘This work presents the subtraction procedure and the Regge cut in the logarithmic Regge pole approach.The subtraction mechanism leads to the same asymptotic behavior as previously obtained in the non-subtraction case.The Regge cut,in contrast,introduces a clear role to the non-leading contributions for the asymptotic behavior of the total cross-section.From these results,some simple parameterization is introduced to fit the experimental data for the proton-proton and antiproton-proton total cross-section above some minimum value up to the cosmic-ray.The fit parameters obtained are used to present predictions for the ρ(s)-parameter as well as to the elastic slope B(s)at high energies.
