In this paper we calculate a synthetic medium surface displacement response that is consistent with real measurement data by applying the least-square principle and a niche genetic algorithm to the parameters inversio...In this paper we calculate a synthetic medium surface displacement response that is consistent with real measurement data by applying the least-square principle and a niche genetic algorithm to the parameters inversion problem of the wave equation in a two-phase medium. We propose a niche genetic multi-parameter (including porosity, solid phase density and fluid phase density) joint inversion algorithm based on a two-phase fractured medium in the BISQ model. We take the two-phase fractured medium of the BISQ model in a two- dimensional half space as an example, and carry out the numerical reservoir parameters inversion. Results show that this method is very convenient for solving the parameters inversion problem for the wave equation in a two-phase medium, and has the advantage of strong noise rejection. Relative to conventional genetic algorithms, the niche genetic algorithm based on a sharing function can not only significantly speed up the convergence, but also improve the inversion precision.展开更多
The surface morphology of Ti-Mg supported catalyst and the polyethyleneparticles are studied using scanning electron microscope(SEM) technology. The results show thateithen the catalyst's surface or polymer partic...The surface morphology of Ti-Mg supported catalyst and the polyethyleneparticles are studied using scanning electron microscope(SEM) technology. The results show thateithen the catalyst's surface or polymer particle's surface is irregular and has fractalcharacteristics, which can be described by fractal parameter. The more interesting discovery is thatthe surface fractal dimension values of the polymer particles vary periodically with thepolymerization time. We call this phenomenon fractal evolution, which can be divided into the'revolution' stage and the 'evolution' stage. And then we present polymerization fractal growingmodel (PFGM), and successfully describe and/or predict the whole evolving process of thepolyethylene particle morphology under the different slurry polymerization (includingpre-polymerization) conditions without H_2.展开更多
The aim of this study is to analyze the difficulties of reading and writing experienced by primary school pupils when writing a script for a theatrical performance called "digestion". Our main research questions are...The aim of this study is to analyze the difficulties of reading and writing experienced by primary school pupils when writing a script for a theatrical performance called "digestion". Our main research questions are: how does a theatrical performance help to reconsider the scripts and to build a model of the digestive system? The pupils were encouraged to stage a theatrical performance for the whole school, explaining the digestion of a sandwich, a glass of water, an apple and a piece of chewing gum. The play helped to develop not only knowledge but also language. Having to produce a text for two different audiences, teachers and other learners led the students to debate between using "academic" vocabulary or more everyday vocabulary. Overall we found that they were more concerned with writing "academic" scripts, influenced by the texts that they consulted, than with writing a play accessible to all audiences.展开更多
A novel weighted evolving network model based on the clique overlapping growth was proposed.The model shows different network characteristics under two different selection mechanisms that are preferential selection an...A novel weighted evolving network model based on the clique overlapping growth was proposed.The model shows different network characteristics under two different selection mechanisms that are preferential selection and random selection.On the basis of mean-field theory,this model under the two different selection mechanisms was analyzed.The analytic equations of distributions of the number of cliques that a vertex joins and the vertex strength of the model were given.It is proved that both distributions follow the scale-free power-law distribution in preferential selection mechanism and the exponential distribution in random selection mechanism,respectively.The analytic expressions of exponents of corresponding distributions were obtained.The agreement between the simulations and analytical results indicates the validity of the theoretical analysis.Finally,three real transport bus networks(BTNs) of Beijing,Shanghai and Hangzhou in China were studied.By analyzing their network properties,it is discovered that these real BTNs belong to a kind of weighted evolving network model with clique overlapping growth and random selection mechanism that was proposed in this context.展开更多
We propose a monomer birth-death model with random removals, in which an aggregate of size k can produce a new monomer at a time-dependent rate I(t)k or lose one monomer at a rate J(t)k, and with a probability P(...We propose a monomer birth-death model with random removals, in which an aggregate of size k can produce a new monomer at a time-dependent rate I(t)k or lose one monomer at a rate J(t)k, and with a probability P(t) an aggregate of any size is randomly removed. We then anedytically investigate the kinetic evolution of the model by means of the rate equation. The results show that the scaling behavior of the aggregate size distribution is dependent crucially on the net birth rate I(t) - J(t) as well as the birth rate I(t). The aggregate size distribution can approach a standard or modified scaling form in some cases, but it may take a scale-free form in other cases. Moreover, the species can survive finally only if either I(t) - J(t) ≥ P(t) or [J(t) + P(t) - I(t)]t ≈ 0 at t ≥ 1; otherwise, it will become extinct.展开更多
Post-translational modification of proteins by N-phosphorylation of the basic amino acid residues plays important roles in biological processes. The high-energy P–N bond might have contributed to the evolution of pre...Post-translational modification of proteins by N-phosphorylation of the basic amino acid residues plays important roles in biological processes. The high-energy P–N bond might have contributed to the evolution of prebiotic chemistry. N-phosphoryl amino acids(PAAs) can serve as interesting small molecular models for the study of P–N bonds in prebiotic chemical evolution. PAAs are capable of simultaneously producing several important biomolecules such as polypeptides and oligonucleotides under mild reaction conditions. In this review, we describe the chemistry of PAAs, discusse their likely prebiotic origins and their reactivity and how they relate to biological P–N bond species. We also depict a possible prebiotic scenario mediated by PAAs in which PAAs may have acted as one of the essential forces driving prebiotic biomolecules to the first protocell.展开更多
In this paper, with the method of adaptive dynamics, we investigate the coevolution of phenotypic traits of predator and prey species. The evolutionary model is constructed from a deterministic approximation of the un...In this paper, with the method of adaptive dynamics, we investigate the coevolution of phenotypic traits of predator and prey species. The evolutionary model is constructed from a deterministic approximation of the underlying stochastic ecological processes. Firstly, we investigate the ecological and evolutionary conditions that allow for continu- ously stable strategy and evolutionary branching. We find that evolutionary branching in the prey phenotype will occur when the frequency dependence in the prey carrying capacity is not strong. Furthermore, it is found that if the two prey branches move far away enough, the evolutionary branching in the prey phenotype will induce the sec- ondary branching in the predator phenotype. The final evolutionary outcome contains two prey and two predator species. Secondly, we show that under symmetric interactions the evolutionary model admits a supercritical Hopf bifurcation if the frequency depen- dence in the prey carrying capa.city is very weak. Evolutionary cycle is a likely outcome of the nmtation-selection processes. Finally, we find that frequency-dependent selection can drive the predator population to extinction under asymmetric interactions.展开更多
The characteristic of enterprise competitiveness is different between different life cycle stages. In this paper we surveyed the enterprise competitiveness's differences in various stages of the life cycle and the ev...The characteristic of enterprise competitiveness is different between different life cycle stages. In this paper we surveyed the enterprise competitiveness's differences in various stages of the life cycle and the evolution model of three aspects of enterprise com- petitiveness as resource, capability and dynamic capability by questionnaire survey. The result shows that there are significant differences between different life cycle stages of en- terprise competitiveness in China. The enterprise competitiveness is stronger and stronger during the periods from the enterprise's birth to maturity, while in the enterprise's recession period the competitiveness becomes much weaker. The competitiveness's constitutive features in each stage are as follows: in the enterprise's born stage the enterprise is lack of resources and its competition mainly relies on the ability; in the enterprise's growth stage the enterprise's resources become richer and are as important as enterprise's ability in the constitution of enterprise competitiveness; in the maturity stage the enterprise's people, money and material resources all become very rich but the role of capability in enterprise competitiveness begins to decrease; in the enterprise's recession stage the en- terprise resources begin to exhaust, and the enterprise's competitiveness returns to rely on capability, and in this period the enterprise's learning ability, innovation ability and dynamic mechanisms perform worst, which will affect the enterprise's revival and lead to the ultimate death of enterprise. These conclusions have great value for reference to the enterprise's competitive strategy making for different life cycle stages.展开更多
基金sponsored by the National Science and Technology Major Project(Grant No.2011ZX05025-001-07)
文摘In this paper we calculate a synthetic medium surface displacement response that is consistent with real measurement data by applying the least-square principle and a niche genetic algorithm to the parameters inversion problem of the wave equation in a two-phase medium. We propose a niche genetic multi-parameter (including porosity, solid phase density and fluid phase density) joint inversion algorithm based on a two-phase fractured medium in the BISQ model. We take the two-phase fractured medium of the BISQ model in a two- dimensional half space as an example, and carry out the numerical reservoir parameters inversion. Results show that this method is very convenient for solving the parameters inversion problem for the wave equation in a two-phase medium, and has the advantage of strong noise rejection. Relative to conventional genetic algorithms, the niche genetic algorithm based on a sharing function can not only significantly speed up the convergence, but also improve the inversion precision.
基金Supported by the National Natural Science Foundation of China (No. 29706010, No. 20203016).
文摘The surface morphology of Ti-Mg supported catalyst and the polyethyleneparticles are studied using scanning electron microscope(SEM) technology. The results show thateithen the catalyst's surface or polymer particle's surface is irregular and has fractalcharacteristics, which can be described by fractal parameter. The more interesting discovery is thatthe surface fractal dimension values of the polymer particles vary periodically with thepolymerization time. We call this phenomenon fractal evolution, which can be divided into the'revolution' stage and the 'evolution' stage. And then we present polymerization fractal growingmodel (PFGM), and successfully describe and/or predict the whole evolving process of thepolyethylene particle morphology under the different slurry polymerization (includingpre-polymerization) conditions without H_2.
文摘The aim of this study is to analyze the difficulties of reading and writing experienced by primary school pupils when writing a script for a theatrical performance called "digestion". Our main research questions are: how does a theatrical performance help to reconsider the scripts and to build a model of the digestive system? The pupils were encouraged to stage a theatrical performance for the whole school, explaining the digestion of a sandwich, a glass of water, an apple and a piece of chewing gum. The play helped to develop not only knowledge but also language. Having to produce a text for two different audiences, teachers and other learners led the students to debate between using "academic" vocabulary or more everyday vocabulary. Overall we found that they were more concerned with writing "academic" scripts, influenced by the texts that they consulted, than with writing a play accessible to all audiences.
基金Projects(60874080,60504027) supported by the National Natural Science Foundation of ChinaProject(20060401037) supported by the National Postdoctor Science Foundation of China
文摘A novel weighted evolving network model based on the clique overlapping growth was proposed.The model shows different network characteristics under two different selection mechanisms that are preferential selection and random selection.On the basis of mean-field theory,this model under the two different selection mechanisms was analyzed.The analytic equations of distributions of the number of cliques that a vertex joins and the vertex strength of the model were given.It is proved that both distributions follow the scale-free power-law distribution in preferential selection mechanism and the exponential distribution in random selection mechanism,respectively.The analytic expressions of exponents of corresponding distributions were obtained.The agreement between the simulations and analytical results indicates the validity of the theoretical analysis.Finally,three real transport bus networks(BTNs) of Beijing,Shanghai and Hangzhou in China were studied.By analyzing their network properties,it is discovered that these real BTNs belong to a kind of weighted evolving network model with clique overlapping growth and random selection mechanism that was proposed in this context.
基金supported by National Natural Science Foundation of China under Grant Nos. 10775104 and 10305009
文摘We propose a monomer birth-death model with random removals, in which an aggregate of size k can produce a new monomer at a time-dependent rate I(t)k or lose one monomer at a rate J(t)k, and with a probability P(t) an aggregate of any size is randomly removed. We then anedytically investigate the kinetic evolution of the model by means of the rate equation. The results show that the scaling behavior of the aggregate size distribution is dependent crucially on the net birth rate I(t) - J(t) as well as the birth rate I(t). The aggregate size distribution can approach a standard or modified scaling form in some cases, but it may take a scale-free form in other cases. Moreover, the species can survive finally only if either I(t) - J(t) ≥ P(t) or [J(t) + P(t) - I(t)]t ≈ 0 at t ≥ 1; otherwise, it will become extinct.
基金supported by the National Basic Research Program of China(2013CB910700,2012CB821600)the National Natural Science Foundation of China(21232005,21375113,21305115)the Program of Chinese Ministry of Education for Changjiang Scholars and Innovative Research Team in University
文摘Post-translational modification of proteins by N-phosphorylation of the basic amino acid residues plays important roles in biological processes. The high-energy P–N bond might have contributed to the evolution of prebiotic chemistry. N-phosphoryl amino acids(PAAs) can serve as interesting small molecular models for the study of P–N bonds in prebiotic chemical evolution. PAAs are capable of simultaneously producing several important biomolecules such as polypeptides and oligonucleotides under mild reaction conditions. In this review, we describe the chemistry of PAAs, discusse their likely prebiotic origins and their reactivity and how they relate to biological P–N bond species. We also depict a possible prebiotic scenario mediated by PAAs in which PAAs may have acted as one of the essential forces driving prebiotic biomolecules to the first protocell.
文摘In this paper, with the method of adaptive dynamics, we investigate the coevolution of phenotypic traits of predator and prey species. The evolutionary model is constructed from a deterministic approximation of the underlying stochastic ecological processes. Firstly, we investigate the ecological and evolutionary conditions that allow for continu- ously stable strategy and evolutionary branching. We find that evolutionary branching in the prey phenotype will occur when the frequency dependence in the prey carrying capacity is not strong. Furthermore, it is found that if the two prey branches move far away enough, the evolutionary branching in the prey phenotype will induce the sec- ondary branching in the predator phenotype. The final evolutionary outcome contains two prey and two predator species. Secondly, we show that under symmetric interactions the evolutionary model admits a supercritical Hopf bifurcation if the frequency depen- dence in the prey carrying capa.city is very weak. Evolutionary cycle is a likely outcome of the nmtation-selection processes. Finally, we find that frequency-dependent selection can drive the predator population to extinction under asymmetric interactions.
文摘The characteristic of enterprise competitiveness is different between different life cycle stages. In this paper we surveyed the enterprise competitiveness's differences in various stages of the life cycle and the evolution model of three aspects of enterprise com- petitiveness as resource, capability and dynamic capability by questionnaire survey. The result shows that there are significant differences between different life cycle stages of en- terprise competitiveness in China. The enterprise competitiveness is stronger and stronger during the periods from the enterprise's birth to maturity, while in the enterprise's recession period the competitiveness becomes much weaker. The competitiveness's constitutive features in each stage are as follows: in the enterprise's born stage the enterprise is lack of resources and its competition mainly relies on the ability; in the enterprise's growth stage the enterprise's resources become richer and are as important as enterprise's ability in the constitution of enterprise competitiveness; in the maturity stage the enterprise's people, money and material resources all become very rich but the role of capability in enterprise competitiveness begins to decrease; in the enterprise's recession stage the en- terprise resources begin to exhaust, and the enterprise's competitiveness returns to rely on capability, and in this period the enterprise's learning ability, innovation ability and dynamic mechanisms perform worst, which will affect the enterprise's revival and lead to the ultimate death of enterprise. These conclusions have great value for reference to the enterprise's competitive strategy making for different life cycle stages.