Urban geography has always been concerned about the influence of human settlements on urban vitality,but few studies reveal the influence of human settlements on urban vitality at a micro-scale.This paper analyzes the...Urban geography has always been concerned about the influence of human settlements on urban vitality,but few studies reveal the influence of human settlements on urban vitality at a micro-scale.This paper analyzes the spatial distribution characteristics of human settlements’quality and urban vitality at the micro-scale using Geodetectors and geographic weighted regression to analyze the relationship between human settlements and urban vitality.The results are shown as follows:there is still a significant development space for human settlements quality in Shahekou District,with obvious spatial dependence characteristics and significant gaps between various systems;the urban vitality of Shahekou District has obvious timeliness,and the urban vitality undergoes significant changes over time,which is related to the human settlements quality.The spatial distribution presents a single core spatial distribution structure with strong relative stability.The spatial distribution of cold and hot spots shows a pattern of“high in the north and low in the south,high in the east and low in the west”,with an increasing trend from southwest to northeast;the reachability of public transport has a significant impact on urban vitality.Its synergy with other variables is the leading force forming the spatial distribution of urban vitality.The environmental system,support system and social system are the significant factors affecting the urban vitality of Shahekou District.展开更多
Young children’s reputation management is closely related to their social development.The purpose of our study is to examine the interaction between theory of mind and partner choice on children’s reputation managem...Young children’s reputation management is closely related to their social development.The purpose of our study is to examine the interaction between theory of mind and partner choice on children’s reputation management.Participants consisted of 270 children who were 3 to 5 years old.First,we measured participants’theory of mind capabilities using the unexpected location task and unexpected content task and then randomly divided the participants into the control group,non-partner–choice group,and partner-choice group.We measured reputation management by comparing children’s willingness to share and sharing behavior between these groups.Thefindings are as follows:(1)Children from ages 3 to 5 demonstrated reputation management,and their reputation management followed a significant developmental trend.The reputation management of 4-to 5-year-old children was significantly better than that of 3-year-old children.(2)Scores on the theory of mind tasks positively predicted children’s reputation management.(3)Partner choice affected children’s reputation management.In the partner-choice group,children’s reputation management was more apparent.(4)Partner choice did moderate the relationship between theory of mind and children’s reputation management.In the partner-choice group,theory of mind had a stronger predictive effect on children’s reputation management.展开更多
Features of human skin in HSV color space are widely applied in the area of image retrieval based on content. H is selected as the basic recognition parameter because its value has a narrow range for the skin color an...Features of human skin in HSV color space are widely applied in the area of image retrieval based on content. H is selected as the basic recognition parameter because its value has a narrow range for the skin color and can keep stable while the illumination intensity or the curvature of skin surface is changing. Rules of parameters with the change of illumination in HSV color space are studied. It is firstly found that the mean of saturation and value (S+V)/2 can keep stable when the illumination intensity is changed or the skin surface is inflected, and (S+V)/2 changes with skin color, but the tendency of change is contrary to that of H. Therefore, (S+V)/H can be used as a new recognition parameter which can enhance HSV ability to recognize human skin.展开更多
Volume diffuse dielectric barrier discharge (DBD) plasma is produced in subsonic airflow by nanosecond high-voltage pulse power supply with a plate-to-plate discharge cell at 6 mm air gap length. The discharge image...Volume diffuse dielectric barrier discharge (DBD) plasma is produced in subsonic airflow by nanosecond high-voltage pulse power supply with a plate-to-plate discharge cell at 6 mm air gap length. The discharge images, optical emission spectra (OES), the applied voltage and current waveforms of the discharge at the changed airflow rates are obtained. When airflow rate is increased, the transition of the discharge mode and the variations of discharge intensity, breakdown characteristics and the temperature of the discharge plasma are investigated. The results show that the discharge becomes more diffuse, discharge intensity is decreased accompanied by the increased breakdown voltage and time lag, and the temperature of the discharge plasma reduces when airflow of small velocity is introduced into the discharge gap. These phenomena are because that the airflow changes the spatial distribution of the heat and the space charge in the discharge gap.展开更多
This paper describe a numerical simulation method for the interaction between laser pulses and low density plasmas based on hydrodynamic approximation. We investigate Backward Raman Amplifying (BRA) experiments and ...This paper describe a numerical simulation method for the interaction between laser pulses and low density plasmas based on hydrodynamic approximation. We investigate Backward Raman Amplifying (BRA) experiments and their variants. The numerical results are in good agreement with experiments.展开更多
Different shapes of dielectric packing beads could affect streamer propagating direction,plasma streamer behavior,and streamer types,such as surface discharge,surface-to-surface discharge,and volume discharge.In this ...Different shapes of dielectric packing beads could affect streamer propagating direction,plasma streamer behavior,and streamer types,such as surface discharge,surface-to-surface discharge,and volume discharge.In this paper,a 2D particle-in-cell/Monte Carlo collision model is used to investigate the effect of the bead shapes on streamer characteristics in packed-bed dielectric barrier discharges.We calculate the electron density,ion density,excitation rate,ionization rate and the electric field with different bead shapes in two cases of seed electron configurations.The results demonstrate that both the configurations of seed electrons and the shape of beads could influence plasma properties.In the case of seed electrons located directly above the beads,the streamer cannot be generated with square beads,while weak surface ionization waves(SIWs)are developed with circle and triangle beads,when the distance between the seed electrons and the upper plate is as close as 0.02 mm.Whereas,the distance between the seed electrons and the upper plate is 0.06 mm,the streamers can be generated with all three bead shapes,but SIWs are still weak.This is because different shapes of beads induce different electric field and surface charging along the dielectric bead surfaces,determining the generation of SIWs.In the case of seed electrons placed between two beads,streamers can propagate in all three bead shape configurations,and the SIWs are enhanced.展开更多
In this paper, we characterize the structure of group graded primitive rings having minimal graded one-sided ideals in terms of graded dual modules. We also show that two structure representations of this class of gra...In this paper, we characterize the structure of group graded primitive rings having minimal graded one-sided ideals in terms of graded dual modules. We also show that two structure representations of this class of graded primitive rings are both in a sense uniquely determined by the graded primitive rings considered.展开更多
We propose an effective and useful numerical simulation scheme for the investigation of the ultra-fast laser pulses in tenuous plasmas. The accuracy of the method is tested by numerical examples. We check some special...We propose an effective and useful numerical simulation scheme for the investigation of the ultra-fast laser pulses in tenuous plasmas. The accuracy of the method is tested by numerical examples. We check some special examples to investigate the laser envelope evolving and modulation in plasmas. Asymmetric two-peak modulation structure is found and its underlying physics is analyzed. The advantages and shortages of the method are also discussed.展开更多
As global economic integration development enters a realization era,English holds a very important position in China's diplomacy as the language is an internationally-used language.Besides,English also plays a ver...As global economic integration development enters a realization era,English holds a very important position in China's diplomacy as the language is an internationally-used language.Besides,English also plays a very important role in our daily life.Colleges and universities should pay more attention in strengthening the development of English teaching courses as they are an important base for cultivating high-quality talents.In the modern teaching of English and American literature courses,college English majors do not only need to teach students English language knowledge but are also required need to strengthen students'knowledge and study of national culture.In this journal,the author investigates and analyses the current situation and existing problems of the modern teaching of English and American literature courses in English majors of colleges and universities.Then,puts forward the implementation strategies such as modern teaching of English and American literature courses in English majors’colleges and universities,aiming to help in implementing the teaching of English and American literature courses successfully.展开更多
As global economic integration development enters a realization era,English holds a very important position in China's diplomacy as the language is an internationally-used language.Besides,English also plays a ver...As global economic integration development enters a realization era,English holds a very important position in China's diplomacy as the language is an internationally-used language.Besides,English also plays a very important role in our daily life.Colleges and universities should pay more attention in strengthening the development of English teaching courses as they are an important base for cultivating high-quality talents.In the modern teaching of English and American literature courses,college English majors do not only need to teach students English language knowledge but are also required need to strengthen students'knowledge and study of national culture.In this journal,the author investigates and analyses the current situation and existing problems of the modern teaching of English and American literature courses in English majors of colleges and universities.Then,puts forward the implementation strategies such as modern teaching of English and American literature courses in English majors’colleges and universities,aiming to help in implementing the teaching of English and American literature courses successfully.展开更多
The language of The Blind Assassin bears a strong taste of game. Narrative language interweaves critical remarks. Escaping from the context and breaking the continuity of narration, the narrator directly comments on t...The language of The Blind Assassin bears a strong taste of game. Narrative language interweaves critical remarks. Escaping from the context and breaking the continuity of narration, the narrator directly comments on the narration, through which the novel also obtains continual adjustment, as if it is gifted a kind of dynamic self-consciousness. The title of the novel is also a kind of word game. The blind assassin' s physical blindness forms a sharp contrast with Iris' s absence of nerves.展开更多
Traditional Chinese sport conveys China's millenniums' culture, which can be taken as symbol of China's culture. Therefore, the application for the status of national intangible cultural heritage becomes unavoidabl...Traditional Chinese sport conveys China's millenniums' culture, which can be taken as symbol of China's culture. Therefore, the application for the status of national intangible cultural heritage becomes unavoidable. No matter it will be successful or not, the process will boost its industry. This paper argued its push to traditional Chinese sport industry from the point of traveling, sporting goods, culture industry and entertainment and relaxation.展开更多
Early time electron-positron correlation in vacuum pair-production in an external field is investigated. The entangled electron and positron wave functions are obtained analytically in the configuration and momentum s...Early time electron-positron correlation in vacuum pair-production in an external field is investigated. The entangled electron and positron wave functions are obtained analytically in the configuration and momentum spaces. It is shown that, relative to that of the one-dimensional theory, two- and three-dimensional calculations yield enhanced spatial correlation and broadened momentum spectra. In fact, at early times the electron and positron almost coincide spatially. The correlation also depends on the direction of the applied field. For the spatial correlation, the transverse correlation is stronger than the longitudinal correlation.展开更多
This paper investigates the stochastic dynamics of trophic cascade chemostat model perturbed by regime switching, Gaussian white noise and impulsive toxicant input. For the system with only white noise interference, s...This paper investigates the stochastic dynamics of trophic cascade chemostat model perturbed by regime switching, Gaussian white noise and impulsive toxicant input. For the system with only white noise interference, sufficient conditions for stochastically ultimate boundedness and stochastically permanence are obtained, and we demonstrate that the stochastic system has at least one nontrivial positive periodic solution. For the system with Markov regime switching, sufficient conditions for extinction of the microorganisms are established. Then we prove the system is ergodic and has a stationary distribution. The results show that both impulsive toxins input and stochastic noise have great effects on the survival and extinction of the microorganisms. Finally, a series of numerical simulations are presented to illustrate the theoretical analysis.展开更多
Using 2-[bis(alkylthio)methylene]-3-oxo-N-o-tolylbutanamides 1 as odorless thiol equivalents, an efficient and odorless synthesis of thioethers has been developed. Promoted by NaOH in EtOH, the cleavage of 1 commenc...Using 2-[bis(alkylthio)methylene]-3-oxo-N-o-tolylbutanamides 1 as odorless thiol equivalents, an efficient and odorless synthesis of thioethers has been developed. Promoted by NaOH in EtOH, the cleavage of 1 commences to generate thiolate anions, and the generated thiolate anions then react with halides to give various thioethers in good yield. It is noteworthy that only a very faint odor ofthiols can be perceived during both the reaction and the workup.展开更多
In this paper,we assume that the pest population is divided into susceptible pests and infected pests,and only susceptible pests do harm to crops.Considering the two methods of spraying pesticides and releasing infect...In this paper,we assume that the pest population is divided into susceptible pests and infected pests,and only susceptible pests do harm to crops.Considering the two methods of spraying pesticides and releasing infected pests and natural enemies to control susceptible pests(the former is applied more frequently),and assuming that only susceptible pests develop resistance to pesticides,a pest control model with resistance development is established.By using the basic theory of impulsive differential systems and analytical methods,the sufficient condition for the global attractiveness of the susceptible pest eradication periodic solution is given.Combined with numerical simulations,the effects of spraying frequency of pesticides on critical threshold conditions for eradicating susceptible pests are discussed.The results confirm that it is not that the more frequently the pesticides are sprayed,the better the result of the pest control is.Two control strategies for eradicating susceptible pests are proposed:switching pesticides and releasing natural enemies elastically.Finally,the parameters in the critical threshold are analyzed from the following two aspects:(1)The key factors affecting pest control are determined by parameter sensitivity analyses.The results indicate that the correlation of the critical threshold concerning the killing efficiency rate and the decay rate of pesticides to susceptible pests varies due to the resistance development of susceptible pests.(2)Three-dimensional graphs and contours of susceptible pest eradication critical threshold with two parameters are simulated,and the effects of the main parameters on the critical threshold are analyzed.展开更多
A cost-effective and environmentally compliance FeCl3·6H2O catalyzed Friedel-Crafts alkylation of cyclic ketene dithioacetals with alcohols was developed. The reaction was efficient in the presence of catalyst lo...A cost-effective and environmentally compliance FeCl3·6H2O catalyzed Friedel-Crafts alkylation of cyclic ketene dithioacetals with alcohols was developed. The reaction was efficient in the presence of catalyst loading as low as 5%(molar fraction) in CH2Cl2 solvent at room temperature or under reflux conditions. A wide range of alkylated ketene dithioacetals were synthesized in excellent yields.展开更多
In this paper,epidemnic diseases among pests are assumed to occur,so pests are divided into susceptible pests and infected pests,and only susceptible pests are harmful to crops.Considering spraying pesticides and rele...In this paper,epidemnic diseases among pests are assumed to occur,so pests are divided into susceptible pests and infected pests,and only susceptible pests are harmful to crops.Considering spraying pesticides and releasing of natural enermies and infected pests to control pests,as well as the long-term application of the same pesticide to induce resistance,an integrated pest management with pesticide resistance is established.The pollution emission model is introduced to model the action process of pesticides,which well reflects its residual and delay effects.By using comparison theorem of impulsive differential equation and analysis method,the threshold condition for eradication of susceptible pests is obtained.Then we analyze the frequency of spraying pesticide on the success of pests control.It shows that it is not that the more frequently pesticides are applied,the better the result of the susceptible pests control is.From the sensitivity analysis,the key factors on the threshold are obtained.Finally,the strategies to control susceptible pests are given,including switching pesticides and releasing infected pests and natural enemies elastically.展开更多
A high-efficiency, low-cost and environmem-friendly 2-acrylamide-2-methyl propane sulfonic acid (AMPS)-modified hazelnut-shell-based adsorbent(AHS) was synthesized and used to adsorb Cu2+, Pb2+, methylene blue...A high-efficiency, low-cost and environmem-friendly 2-acrylamide-2-methyl propane sulfonic acid (AMPS)-modified hazelnut-shell-based adsorbent(AHS) was synthesized and used to adsorb Cu2+, Pb2+, methylene blue(MB) and malachite green(MG) from aqueous solutions. The AHS was characterized by means of SEM, BET, FTIR and XPS. Different experimental parameters were evaluated in batch adsorption experiments to determine the optimal adsorption conditions. Adsorption kinetics shows that the adsorption rate is well represented by the pseudo- secend-order rate model, and the Langmuir model gives the best fit adsorption isotherm. The Langmuir maximum adsorption capacities were fotmd to be 21.14 mg/g for Cu2+, 32.74 mg/g for Pb2+, 68.03 mg/g for MB and 263.16 mg/g for MG, respectively, while the adsorption capacities could be maintained above 90% even after ten adsorp- tion-desorption cycles. The experimental results show that AHS could be applied to treat both industrial and munici- pal wastewaters.展开更多
A mathematical model for the dynamics of a prey-dependent consumption model concerning integrated pest management is proposed and analyzed. We show that there exists a globally stable pesteradication periodic solution...A mathematical model for the dynamics of a prey-dependent consumption model concerning integrated pest management is proposed and analyzed. We show that there exists a globally stable pesteradication periodic solution when the impulsive period is less than some critical values. Furthermore, the conditions for the permanence of the system are given. By using bifurcation theory, we show the existence of a nontrival periodic solution if the pest-eradication periodic solution loses its stability. When the unique positive periodic solution loses its stability, numerical simulation shows there is a characteristic sequence of bifurcations, leading to a chaotic dynamics, which implies that dynamical behaviors of prey-dependent consumption concerning integrated pest management are very complex, including period-doubling cascades, chaotic bands with periodic windows, crises, symmetry-breaking bifurcations and supertransients.展开更多
文摘Urban geography has always been concerned about the influence of human settlements on urban vitality,but few studies reveal the influence of human settlements on urban vitality at a micro-scale.This paper analyzes the spatial distribution characteristics of human settlements’quality and urban vitality at the micro-scale using Geodetectors and geographic weighted regression to analyze the relationship between human settlements and urban vitality.The results are shown as follows:there is still a significant development space for human settlements quality in Shahekou District,with obvious spatial dependence characteristics and significant gaps between various systems;the urban vitality of Shahekou District has obvious timeliness,and the urban vitality undergoes significant changes over time,which is related to the human settlements quality.The spatial distribution presents a single core spatial distribution structure with strong relative stability.The spatial distribution of cold and hot spots shows a pattern of“high in the north and low in the south,high in the east and low in the west”,with an increasing trend from southwest to northeast;the reachability of public transport has a significant impact on urban vitality.Its synergy with other variables is the leading force forming the spatial distribution of urban vitality.The environmental system,support system and social system are the significant factors affecting the urban vitality of Shahekou District.
文摘Young children’s reputation management is closely related to their social development.The purpose of our study is to examine the interaction between theory of mind and partner choice on children’s reputation management.Participants consisted of 270 children who were 3 to 5 years old.First,we measured participants’theory of mind capabilities using the unexpected location task and unexpected content task and then randomly divided the participants into the control group,non-partner–choice group,and partner-choice group.We measured reputation management by comparing children’s willingness to share and sharing behavior between these groups.Thefindings are as follows:(1)Children from ages 3 to 5 demonstrated reputation management,and their reputation management followed a significant developmental trend.The reputation management of 4-to 5-year-old children was significantly better than that of 3-year-old children.(2)Scores on the theory of mind tasks positively predicted children’s reputation management.(3)Partner choice affected children’s reputation management.In the partner-choice group,children’s reputation management was more apparent.(4)Partner choice did moderate the relationship between theory of mind and children’s reputation management.In the partner-choice group,theory of mind had a stronger predictive effect on children’s reputation management.
文摘Features of human skin in HSV color space are widely applied in the area of image retrieval based on content. H is selected as the basic recognition parameter because its value has a narrow range for the skin color and can keep stable while the illumination intensity or the curvature of skin surface is changing. Rules of parameters with the change of illumination in HSV color space are studied. It is firstly found that the mean of saturation and value (S+V)/2 can keep stable when the illumination intensity is changed or the skin surface is inflected, and (S+V)/2 changes with skin color, but the tendency of change is contrary to that of H. Therefore, (S+V)/H can be used as a new recognition parameter which can enhance HSV ability to recognize human skin.
基金supported by National Natural Science Foundation of China(No.51437002)
文摘Volume diffuse dielectric barrier discharge (DBD) plasma is produced in subsonic airflow by nanosecond high-voltage pulse power supply with a plate-to-plate discharge cell at 6 mm air gap length. The discharge images, optical emission spectra (OES), the applied voltage and current waveforms of the discharge at the changed airflow rates are obtained. When airflow rate is increased, the transition of the discharge mode and the variations of discharge intensity, breakdown characteristics and the temperature of the discharge plasma are investigated. The results show that the discharge becomes more diffuse, discharge intensity is decreased accompanied by the increased breakdown voltage and time lag, and the temperature of the discharge plasma reduces when airflow of small velocity is introduced into the discharge gap. These phenomena are because that the airflow changes the spatial distribution of the heat and the space charge in the discharge gap.
文摘This paper describe a numerical simulation method for the interaction between laser pulses and low density plasmas based on hydrodynamic approximation. We investigate Backward Raman Amplifying (BRA) experiments and their variants. The numerical results are in good agreement with experiments.
基金the National Magnetic Confinement Fusion Energy Research Project(Nos.2017YFE0301803 and 2015GB120003)National Natural Science Foundation of China(Nos.11775164 and 11775090)the Fundamental Research Funds for the Central Universities(WUT:2017IVA79 and 2018IB011).
文摘Different shapes of dielectric packing beads could affect streamer propagating direction,plasma streamer behavior,and streamer types,such as surface discharge,surface-to-surface discharge,and volume discharge.In this paper,a 2D particle-in-cell/Monte Carlo collision model is used to investigate the effect of the bead shapes on streamer characteristics in packed-bed dielectric barrier discharges.We calculate the electron density,ion density,excitation rate,ionization rate and the electric field with different bead shapes in two cases of seed electron configurations.The results demonstrate that both the configurations of seed electrons and the shape of beads could influence plasma properties.In the case of seed electrons located directly above the beads,the streamer cannot be generated with square beads,while weak surface ionization waves(SIWs)are developed with circle and triangle beads,when the distance between the seed electrons and the upper plate is as close as 0.02 mm.Whereas,the distance between the seed electrons and the upper plate is 0.06 mm,the streamers can be generated with all three bead shapes,but SIWs are still weak.This is because different shapes of beads induce different electric field and surface charging along the dielectric bead surfaces,determining the generation of SIWs.In the case of seed electrons placed between two beads,streamers can propagate in all three bead shape configurations,and the SIWs are enhanced.
基金Foundation item:The NSF(993521738)of Liaoning Education Department
文摘In this paper, we characterize the structure of group graded primitive rings having minimal graded one-sided ideals in terms of graded dual modules. We also show that two structure representations of this class of graded primitive rings are both in a sense uniquely determined by the graded primitive rings considered.
基金The project supported by National Natural Science Foundation of China under Grant No. 10475009 and the New Century Excellent Talents of Universities of China
文摘We propose an effective and useful numerical simulation scheme for the investigation of the ultra-fast laser pulses in tenuous plasmas. The accuracy of the method is tested by numerical examples. We check some special examples to investigate the laser envelope evolving and modulation in plasmas. Asymmetric two-peak modulation structure is found and its underlying physics is analyzed. The advantages and shortages of the method are also discussed.
文摘As global economic integration development enters a realization era,English holds a very important position in China's diplomacy as the language is an internationally-used language.Besides,English also plays a very important role in our daily life.Colleges and universities should pay more attention in strengthening the development of English teaching courses as they are an important base for cultivating high-quality talents.In the modern teaching of English and American literature courses,college English majors do not only need to teach students English language knowledge but are also required need to strengthen students'knowledge and study of national culture.In this journal,the author investigates and analyses the current situation and existing problems of the modern teaching of English and American literature courses in English majors of colleges and universities.Then,puts forward the implementation strategies such as modern teaching of English and American literature courses in English majors’colleges and universities,aiming to help in implementing the teaching of English and American literature courses successfully.
文摘As global economic integration development enters a realization era,English holds a very important position in China's diplomacy as the language is an internationally-used language.Besides,English also plays a very important role in our daily life.Colleges and universities should pay more attention in strengthening the development of English teaching courses as they are an important base for cultivating high-quality talents.In the modern teaching of English and American literature courses,college English majors do not only need to teach students English language knowledge but are also required need to strengthen students'knowledge and study of national culture.In this journal,the author investigates and analyses the current situation and existing problems of the modern teaching of English and American literature courses in English majors of colleges and universities.Then,puts forward the implementation strategies such as modern teaching of English and American literature courses in English majors’colleges and universities,aiming to help in implementing the teaching of English and American literature courses successfully.
文摘The language of The Blind Assassin bears a strong taste of game. Narrative language interweaves critical remarks. Escaping from the context and breaking the continuity of narration, the narrator directly comments on the narration, through which the novel also obtains continual adjustment, as if it is gifted a kind of dynamic self-consciousness. The title of the novel is also a kind of word game. The blind assassin' s physical blindness forms a sharp contrast with Iris' s absence of nerves.
文摘Traditional Chinese sport conveys China's millenniums' culture, which can be taken as symbol of China's culture. Therefore, the application for the status of national intangible cultural heritage becomes unavoidable. No matter it will be successful or not, the process will boost its industry. This paper argued its push to traditional Chinese sport industry from the point of traveling, sporting goods, culture industry and entertainment and relaxation.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11175023 and 11247007, partially by the Open Fund of National Laboratory of Science and Technology on Computational Physics at IAPCM, the Open Fund of the State Key Laboratory of High Field Laser Physics at SIOM, and the Ministry of Science and Technology of China under Grant No 2011GB105000.
文摘Early time electron-positron correlation in vacuum pair-production in an external field is investigated. The entangled electron and positron wave functions are obtained analytically in the configuration and momentum spaces. It is shown that, relative to that of the one-dimensional theory, two- and three-dimensional calculations yield enhanced spatial correlation and broadened momentum spectra. In fact, at early times the electron and positron almost coincide spatially. The correlation also depends on the direction of the applied field. For the spatial correlation, the transverse correlation is stronger than the longitudinal correlation.
基金the National Natural Science Foundation of China (No.12271308)the Research Fund for the Taishan Scholar Project of Shandong Province of ChinaShandong Provincial Natural Science Foundation of China (ZR2019MA003)。
文摘This paper investigates the stochastic dynamics of trophic cascade chemostat model perturbed by regime switching, Gaussian white noise and impulsive toxicant input. For the system with only white noise interference, sufficient conditions for stochastically ultimate boundedness and stochastically permanence are obtained, and we demonstrate that the stochastic system has at least one nontrivial positive periodic solution. For the system with Markov regime switching, sufficient conditions for extinction of the microorganisms are established. Then we prove the system is ergodic and has a stationary distribution. The results show that both impulsive toxins input and stochastic noise have great effects on the survival and extinction of the microorganisms. Finally, a series of numerical simulations are presented to illustrate the theoretical analysis.
基金This work was supported by the National Natural Science Foundation of China (No. 20572013) and the Doctoral Foundation of Anshan Normal University.
文摘Using 2-[bis(alkylthio)methylene]-3-oxo-N-o-tolylbutanamides 1 as odorless thiol equivalents, an efficient and odorless synthesis of thioethers has been developed. Promoted by NaOH in EtOH, the cleavage of 1 commences to generate thiolate anions, and the generated thiolate anions then react with halides to give various thioethers in good yield. It is noteworthy that only a very faint odor ofthiols can be perceived during both the reaction and the workup.
基金supported by the National Natural Science Foundation of China(No.11371030)the Natural Science Foundation of Liaoning Province(No.20170540001)Liaoning Bai Qian Wan Talents Program。
文摘In this paper,we assume that the pest population is divided into susceptible pests and infected pests,and only susceptible pests do harm to crops.Considering the two methods of spraying pesticides and releasing infected pests and natural enemies to control susceptible pests(the former is applied more frequently),and assuming that only susceptible pests develop resistance to pesticides,a pest control model with resistance development is established.By using the basic theory of impulsive differential systems and analytical methods,the sufficient condition for the global attractiveness of the susceptible pest eradication periodic solution is given.Combined with numerical simulations,the effects of spraying frequency of pesticides on critical threshold conditions for eradicating susceptible pests are discussed.The results confirm that it is not that the more frequently the pesticides are sprayed,the better the result of the pest control is.Two control strategies for eradicating susceptible pests are proposed:switching pesticides and releasing natural enemies elastically.Finally,the parameters in the critical threshold are analyzed from the following two aspects:(1)The key factors affecting pest control are determined by parameter sensitivity analyses.The results indicate that the correlation of the critical threshold concerning the killing efficiency rate and the decay rate of pesticides to susceptible pests varies due to the resistance development of susceptible pests.(2)Three-dimensional graphs and contours of susceptible pest eradication critical threshold with two parameters are simulated,and the effects of the main parameters on the critical threshold are analyzed.
基金Supported by the National Natural Science Foundation of China(No,20902010), the Foundation of Liaoning Provincial Education Administration, China(No.L2015003) and the Science Foundation of Anshan City, China(Nos.2012KJ02, 2014KJ05).
文摘A cost-effective and environmentally compliance FeCl3·6H2O catalyzed Friedel-Crafts alkylation of cyclic ketene dithioacetals with alcohols was developed. The reaction was efficient in the presence of catalyst loading as low as 5%(molar fraction) in CH2Cl2 solvent at room temperature or under reflux conditions. A wide range of alkylated ketene dithioacetals were synthesized in excellent yields.
基金This work was supported by the National Natural Science Foundation of China(11371030)the Natural Science Foundation of Liaoning Province(20170540001)。
文摘In this paper,epidemnic diseases among pests are assumed to occur,so pests are divided into susceptible pests and infected pests,and only susceptible pests are harmful to crops.Considering spraying pesticides and releasing of natural enermies and infected pests to control pests,as well as the long-term application of the same pesticide to induce resistance,an integrated pest management with pesticide resistance is established.The pollution emission model is introduced to model the action process of pesticides,which well reflects its residual and delay effects.By using comparison theorem of impulsive differential equation and analysis method,the threshold condition for eradication of susceptible pests is obtained.Then we analyze the frequency of spraying pesticide on the success of pests control.It shows that it is not that the more frequently pesticides are applied,the better the result of the susceptible pests control is.From the sensitivity analysis,the key factors on the threshold are obtained.Finally,the strategies to control susceptible pests are given,including switching pesticides and releasing infected pests and natural enemies elastically.
文摘A high-efficiency, low-cost and environmem-friendly 2-acrylamide-2-methyl propane sulfonic acid (AMPS)-modified hazelnut-shell-based adsorbent(AHS) was synthesized and used to adsorb Cu2+, Pb2+, methylene blue(MB) and malachite green(MG) from aqueous solutions. The AHS was characterized by means of SEM, BET, FTIR and XPS. Different experimental parameters were evaluated in batch adsorption experiments to determine the optimal adsorption conditions. Adsorption kinetics shows that the adsorption rate is well represented by the pseudo- secend-order rate model, and the Langmuir model gives the best fit adsorption isotherm. The Langmuir maximum adsorption capacities were fotmd to be 21.14 mg/g for Cu2+, 32.74 mg/g for Pb2+, 68.03 mg/g for MB and 263.16 mg/g for MG, respectively, while the adsorption capacities could be maintained above 90% even after ten adsorp- tion-desorption cycles. The experimental results show that AHS could be applied to treat both industrial and munici- pal wastewaters.
基金This work is supported by National Natural Science Foundation of China (10171106)supported by ScienceResearch Project Foundation of Liaoning Province Education Department
文摘A mathematical model for the dynamics of a prey-dependent consumption model concerning integrated pest management is proposed and analyzed. We show that there exists a globally stable pesteradication periodic solution when the impulsive period is less than some critical values. Furthermore, the conditions for the permanence of the system are given. By using bifurcation theory, we show the existence of a nontrival periodic solution if the pest-eradication periodic solution loses its stability. When the unique positive periodic solution loses its stability, numerical simulation shows there is a characteristic sequence of bifurcations, leading to a chaotic dynamics, which implies that dynamical behaviors of prey-dependent consumption concerning integrated pest management are very complex, including period-doubling cascades, chaotic bands with periodic windows, crises, symmetry-breaking bifurcations and supertransients.