Given a set U which is consisted of strings defined on alphabet Σ, string cross pattern matching is to find all the matches between every two strings in U. It is utilized in text processing like removing the duplicat...Given a set U which is consisted of strings defined on alphabet Σ, string cross pattern matching is to find all the matches between every two strings in U. It is utilized in text processing like removing the duplication of strings. This paper presents a fast string cross pattern matching algorithm based on extracting high frequency strings. Compared with existing algorithms including single-pattern algorithms and multi-pattern matching algorithms, this algorithm is featured by both low time complexity and low space complexity. Because Chinese alphabet is large and the average length of Chinese words is much short, this algorithm is more suitable to process the text written by Chinese, especially when the size of Σ is large and the number of strings is far more than the maximum length of strings of set U.展开更多
This paper considers the Holling-Tanner model for predator-prey with self and cross-diffusion. From the Turing theory, it is believed that there is no Turing pattern formation for the equal self-diffusion coefficients...This paper considers the Holling-Tanner model for predator-prey with self and cross-diffusion. From the Turing theory, it is believed that there is no Turing pattern formation for the equal self-diffusion coefficients. However, combined with cross-diffusion, it shows that the system will exhibit spotted pattern by both mathematical analysis and numerical simulations. Furthermore, asynchrony of the predator and the prey in the space. The obtained results show that cross-diffusion plays an important role on the pattern formation of the predator-prey system.展开更多
In this companion paper, flow patterns in the upstream and downstream tubes of a sudden-expansion
cross-section (SECS) in a vertical straight pipe were presented. The effect of SECS on flow patterns upstream
and do...In this companion paper, flow patterns in the upstream and downstream tubes of a sudden-expansion
cross-section (SECS) in a vertical straight pipe were presented. The effect of SECS on flow patterns upstream
and downstream was analyzed by comparing with flow patterns in uniform cross-section vertical tubes. It is found the effect is great. There exist great instabilities of two-phase flow in the neighboring areas of the SECS both downstream and upstream.展开更多
Flow patterns upstream and downstream of a sudden-contraction cross-section in a vertical straight pipe were presented. By comparing with flow patterns in uniform cross-section vertical tubes, the effect of the sudde...Flow patterns upstream and downstream of a sudden-contraction cross-section in a vertical straight pipe were presented. By comparing with flow patterns in uniform cross-section vertical tubes, the effect of the sudden change in pipe diameter on flow patterns was analyzed. Flow pattern transition mechanisms were discussed and transition criteria for flow pattern transitions were deduced accordingly using the dimensional analysis.展开更多
A chemostat model with maintenance energy and crossdiffusion is considered,and the formation of patterns is caused by the cross-diffusion. First, through linear stability analysis, the necessary conditions for the for...A chemostat model with maintenance energy and crossdiffusion is considered,and the formation of patterns is caused by the cross-diffusion. First, through linear stability analysis, the necessary conditions for the formation of the spatial patterns are given. Then numerical simulations by changing the values of crossdiffusions in the unstable domain are performed. The results showthat the cross-diffusion coefficient plays an important role in the formation of the pattern, and the different values of the crossdiffusion coefficients may lead to different types of pattern formation.展开更多
In this paper, we present the amplitude equations for the excited modes in a cross-diffusive predator-prey model with zero-flux boundary conditions. From these equations, the stability of patterns towards uniform and ...In this paper, we present the amplitude equations for the excited modes in a cross-diffusive predator-prey model with zero-flux boundary conditions. From these equations, the stability of patterns towards uniform and inhomogenous perturbations is determined. Furthermore, we present novel numerical evidence of six typical turing patterns, and find that the model dynamics exhibits complex pattern replications: for μ1 〈μ ≤μ2, the steady state is the only stable solution of the model; for μ2 〈 μ ≤ μ4, by increasing the control parameter μ, the sequence Hπ-hexagons→ Hπ- hexagon-stripe mixtures → stripes → H0-hexagon-stripe mixtures → H0-hexagons is observed; for μ 〉 μ4, the stripe pattern emerges. This may enrich the pattern formation in the cross-diffusive predatorprey model.展开更多
The Turing instability and the phenomena of pattern formation for a nonlinear reaction-diffusion(RD) system of turbulence-shear flowinteraction are investigated.By the linear stability analysis,the essential condition...The Turing instability and the phenomena of pattern formation for a nonlinear reaction-diffusion(RD) system of turbulence-shear flowinteraction are investigated.By the linear stability analysis,the essential conditions for Turing instability are obtained.It indicates that the emergence of cross-diffusion terms leads to the destabilizing mechanism.Then the amplitude equations and the asymptotic solutions of the model closed to the onset of instability are derived by using the weakly nonlinear analysis.展开更多
Flow patterns in upstream and downstream straight tubes of sudden-changed areas in a horizontal straight pipe were experimentally examined. Both sudden-expansion cross-section (SECS) and sudden-contraction cross-secti...Flow patterns in upstream and downstream straight tubes of sudden-changed areas in a horizontal straight pipe were experimentally examined. Both sudden-expansion cross-section (SECS) and sudden-contraction cross-section (SCCS) were investigated. The flow pattern maps upstream and downstream were delineated and compared with those in straight tubes with uniform cross-sections. The effects of the SECS and SCCS on flow patterns were discussed and analyzed. Furthermore, flow pattern transition mechanisms resulting in occurrences of different flow patterns were simply discussed and some transition criteria for the flow pattern transitions were deduced by using the non-dimensionlized analysis method.展开更多
Aiming at the safety distance between coal mining working face and natural gas wells in the cross-mining area of multiple mineral resources, the cross- mining area of gas and coal resources in the Ordos Basin is taken...Aiming at the safety distance between coal mining working face and natural gas wells in the cross-mining area of multiple mineral resources, the cross- mining area of gas and coal resources in the Ordos Basin is taken as the engineering background. An anti-collision early warning technology method based on vibration wave propagation attenuation monitoring is proposed to prevent collision accidents between road headers and natural gas wells. Through the steel pipe and steel pipe concrete knocking vibration test and underground digging vibration test, the research results show that: The exponential decay coefficients of the vibration wave in steel pipe, steel pipe concrete and coal rock respectively are 0.1, 0.1140 and 0.03, which are all in accordance with the exponential decay law, and the vibration wave firstly decays sharply and then decays slowly;the formula for the distance from the road header to the natural gas well was derived based on the vibration attenuation formula, to provide a new method for realizing the problem of precise and coordinated extraction by surface monitoring of the distance from down hole road headers to gas wells, collision prevention prediction and warning and prevention of collision of extraction equipment with gas wells.展开更多
Background: Occupational health is an important consideration, especially for people that work in an environment with pollutants. Gasoline attendants are individuals that work in filling stations. They are constantly ...Background: Occupational health is an important consideration, especially for people that work in an environment with pollutants. Gasoline attendants are individuals that work in filling stations. They are constantly exposed to gasoline fumes and automobile engine products from vehicle exhaust. This increases the risk of acute and chronic respiratory diseases and carcinogenesis among them. The risk of health complications tends to increase with the duration of exposure. The study aimed to determine the proportion of gasoline attendants with lung function impairment. Methods and Materials: Two hundred and eight eligible participants were recruited for this study. A cross-sectional analytical study was carried out in Esan West local government area of Edo state, Nigeria. The study was carried out for a period of six months from December 2015 to May 2016. A questionnaire was used to obtain information on demographic characteristics, work history, mode of exposure and duration of exposure to petrol fumes. Lung function was assessed using a DTspiro spirometer (Model POP 10. Serial no 110843-005);also the anthropometric parameters of the respondent were measured. Statistical analysis was done using IBM SPSS version 20.0. Frequency and percentages were used to present categorical data. The mean and standard deviation of continuous variables were calculated and compared using the student’s t-test. The criteria of significant association were assumed for a p-value less than 0.05. Results: A total of one hundred and forty petrol pump attendants and one hundred and forty controls participated in this study. The mean age for petrol pump attendants was 24 ± 3.1 years and 23 ± 2.8 years for the control group. There were no significant differences in the gender distribution and anthropometric parameters as observed in this study. The lung impairment pattern observed in this study was obstructive in twelve (8.6%) gasoline pump attendants and restrictive pattern in thirty-nine (27.9%) gasoline pump attendants, while only four (2.9%) had an obstructive pattern and twelve (8.6%) had a restrictive pattern of lung impairment among the control group. This implies that a restrictive pattern was predominant. This study also observed that there was an increase in the number of gasoline pump attendants with declined lung function compared to the control group. Conclusion: Restrictive pattern of lung impairment was more predominant than the obstructive pattern among gasoline pump attendants. As a result, public health interventions should be instituted among these individuals, especially in developing countries.展开更多
Background: Occupational health is an important consideration, especially for people that work in an environment with pollutants. Gasoline attendants are individuals that work in filling stations. They are constantly ...Background: Occupational health is an important consideration, especially for people that work in an environment with pollutants. Gasoline attendants are individuals that work in filling stations. They are constantly exposed to gasoline fumes and automobile engine products from vehicle exhaust. This increases the risk of acute and chronic respiratory diseases and carcinogenesis among them. The risk of health complications tends to increase with the duration of exposure. The study aimed to determine the proportion of gasoline attendants with lung function impairment. Methods and Materials: Two hundred and eight eligible participants were recruited for this study. A cross-sectional analytical study was carried out in Esan West local government area of Edo state, Nigeria. The study was carried out for a period of six months from December 2015 to May 2016. A questionnaire was used to obtain information on demographic characteristics, work history, mode of exposure and duration of exposure to petrol fumes. Lung function was assessed using a DTspiro spirometer (Model POP 10. Serial no 110843-005);also the anthropometric parameters of the respondent were measured. Statistical analysis was done using IBM SPSS version 20.0. Frequency and percentages were used to present categorical data. The mean and standard deviation of continuous variables were calculated and compared using the student’s t-test. The criteria of significant association were assumed for a p-value less than 0.05. Results: A total of one hundred and forty petrol pump attendants and one hundred and forty controls participated in this study. The mean age for petrol pump attendants was 24 ± 3.1 years and 23 ± 2.8 years for the control group. There were no significant differences in the gender distribution and anthropometric parameters as observed in this study. The lung impairment pattern observed in this study was obstructive in twelve (8.6%) gasoline pump attendants and restrictive pattern in thirty-nine (27.9%) gasoline pump attendants, while only four (2.9%) had an obstructive pattern and twelve (8.6%) had a restrictive pattern of lung impairment among the control group. This implies that a restrictive pattern was predominant. This study also observed that there was an increase in the number of gasoline pump attendants with declined lung function compared to the control group. Conclusion: Restrictive pattern of lung impairment was more predominant than the obstructive pattern among gasoline pump attendants. As a result, public health interventions should be instituted among these individuals, especially in developing countries.展开更多
文摘Given a set U which is consisted of strings defined on alphabet Σ, string cross pattern matching is to find all the matches between every two strings in U. It is utilized in text processing like removing the duplication of strings. This paper presents a fast string cross pattern matching algorithm based on extracting high frequency strings. Compared with existing algorithms including single-pattern algorithms and multi-pattern matching algorithms, this algorithm is featured by both low time complexity and low space complexity. Because Chinese alphabet is large and the average length of Chinese words is much short, this algorithm is more suitable to process the text written by Chinese, especially when the size of Σ is large and the number of strings is far more than the maximum length of strings of set U.
基金Project supported by the National Natural Science Foundation of China (Grant No 60771026)Program for New Century Excellent Talents in University of China (Grant No NCET050271)the Special Scientific Research Foundation for the Subjects of Doctors in University of China (Grant No 20060110005)
文摘This paper considers the Holling-Tanner model for predator-prey with self and cross-diffusion. From the Turing theory, it is believed that there is no Turing pattern formation for the equal self-diffusion coefficients. However, combined with cross-diffusion, it shows that the system will exhibit spotted pattern by both mathematical analysis and numerical simulations. Furthermore, asynchrony of the predator and the prey in the space. The obtained results show that cross-diffusion plays an important role on the pattern formation of the predator-prey system.
基金the National Natural Science Foundation of China (No. 59236130).
文摘In this companion paper, flow patterns in the upstream and downstream tubes of a sudden-expansion
cross-section (SECS) in a vertical straight pipe were presented. The effect of SECS on flow patterns upstream
and downstream was analyzed by comparing with flow patterns in uniform cross-section vertical tubes. It is found the effect is great. There exist great instabilities of two-phase flow in the neighboring areas of the SECS both downstream and upstream.
基金the National Natrual Science Foundation of China (No. 59236130).
文摘Flow patterns upstream and downstream of a sudden-contraction cross-section in a vertical straight pipe were presented. By comparing with flow patterns in uniform cross-section vertical tubes, the effect of the sudden change in pipe diameter on flow patterns was analyzed. Flow pattern transition mechanisms were discussed and transition criteria for flow pattern transitions were deduced accordingly using the dimensional analysis.
基金National Natural Science Foundation of China(No.11571227)
文摘A chemostat model with maintenance energy and crossdiffusion is considered,and the formation of patterns is caused by the cross-diffusion. First, through linear stability analysis, the necessary conditions for the formation of the spatial patterns are given. Then numerical simulations by changing the values of crossdiffusions in the unstable domain are performed. The results showthat the cross-diffusion coefficient plays an important role in the formation of the pattern, and the different values of the crossdiffusion coefficients may lead to different types of pattern formation.
基金supported by the Natural Science Foundation of Zhejiang Province,China (Grant No. Y7080041)the Shanghai Postdoctoral Scientific Program,China (Grant No. 09R21410700)
文摘In this paper, we present the amplitude equations for the excited modes in a cross-diffusive predator-prey model with zero-flux boundary conditions. From these equations, the stability of patterns towards uniform and inhomogenous perturbations is determined. Furthermore, we present novel numerical evidence of six typical turing patterns, and find that the model dynamics exhibits complex pattern replications: for μ1 〈μ ≤μ2, the steady state is the only stable solution of the model; for μ2 〈 μ ≤ μ4, by increasing the control parameter μ, the sequence Hπ-hexagons→ Hπ- hexagon-stripe mixtures → stripes → H0-hexagon-stripe mixtures → H0-hexagons is observed; for μ 〉 μ4, the stripe pattern emerges. This may enrich the pattern formation in the cross-diffusive predatorprey model.
基金National Natural Science Foundation of China(No.11371087)
文摘The Turing instability and the phenomena of pattern formation for a nonlinear reaction-diffusion(RD) system of turbulence-shear flowinteraction are investigated.By the linear stability analysis,the essential conditions for Turing instability are obtained.It indicates that the emergence of cross-diffusion terms leads to the destabilizing mechanism.Then the amplitude equations and the asymptotic solutions of the model closed to the onset of instability are derived by using the weakly nonlinear analysis.
基金the National Natural Science Foundation (No.59995460)
文摘Flow patterns in upstream and downstream straight tubes of sudden-changed areas in a horizontal straight pipe were experimentally examined. Both sudden-expansion cross-section (SECS) and sudden-contraction cross-section (SCCS) were investigated. The flow pattern maps upstream and downstream were delineated and compared with those in straight tubes with uniform cross-sections. The effects of the SECS and SCCS on flow patterns were discussed and analyzed. Furthermore, flow pattern transition mechanisms resulting in occurrences of different flow patterns were simply discussed and some transition criteria for the flow pattern transitions were deduced by using the non-dimensionlized analysis method.
基金Acknowledgements: This work is supported by the National Natural Science Foundation of China (No. 60205007), Natural Science Foundation of Guangdong Province (No.031558, No. 04300462), Research Foundation of National Science and Technology Plan Project (No.2004BA721A02), Research Foundation of Science and Technology Plan Project in Guangdong Province (No.2003C50118), and Research Foundation of Science and Technology Plan Project in Guangzhou City (No.2002Z3-E0017).
文摘Aiming at the safety distance between coal mining working face and natural gas wells in the cross-mining area of multiple mineral resources, the cross- mining area of gas and coal resources in the Ordos Basin is taken as the engineering background. An anti-collision early warning technology method based on vibration wave propagation attenuation monitoring is proposed to prevent collision accidents between road headers and natural gas wells. Through the steel pipe and steel pipe concrete knocking vibration test and underground digging vibration test, the research results show that: The exponential decay coefficients of the vibration wave in steel pipe, steel pipe concrete and coal rock respectively are 0.1, 0.1140 and 0.03, which are all in accordance with the exponential decay law, and the vibration wave firstly decays sharply and then decays slowly;the formula for the distance from the road header to the natural gas well was derived based on the vibration attenuation formula, to provide a new method for realizing the problem of precise and coordinated extraction by surface monitoring of the distance from down hole road headers to gas wells, collision prevention prediction and warning and prevention of collision of extraction equipment with gas wells.
文摘Background: Occupational health is an important consideration, especially for people that work in an environment with pollutants. Gasoline attendants are individuals that work in filling stations. They are constantly exposed to gasoline fumes and automobile engine products from vehicle exhaust. This increases the risk of acute and chronic respiratory diseases and carcinogenesis among them. The risk of health complications tends to increase with the duration of exposure. The study aimed to determine the proportion of gasoline attendants with lung function impairment. Methods and Materials: Two hundred and eight eligible participants were recruited for this study. A cross-sectional analytical study was carried out in Esan West local government area of Edo state, Nigeria. The study was carried out for a period of six months from December 2015 to May 2016. A questionnaire was used to obtain information on demographic characteristics, work history, mode of exposure and duration of exposure to petrol fumes. Lung function was assessed using a DTspiro spirometer (Model POP 10. Serial no 110843-005);also the anthropometric parameters of the respondent were measured. Statistical analysis was done using IBM SPSS version 20.0. Frequency and percentages were used to present categorical data. The mean and standard deviation of continuous variables were calculated and compared using the student’s t-test. The criteria of significant association were assumed for a p-value less than 0.05. Results: A total of one hundred and forty petrol pump attendants and one hundred and forty controls participated in this study. The mean age for petrol pump attendants was 24 ± 3.1 years and 23 ± 2.8 years for the control group. There were no significant differences in the gender distribution and anthropometric parameters as observed in this study. The lung impairment pattern observed in this study was obstructive in twelve (8.6%) gasoline pump attendants and restrictive pattern in thirty-nine (27.9%) gasoline pump attendants, while only four (2.9%) had an obstructive pattern and twelve (8.6%) had a restrictive pattern of lung impairment among the control group. This implies that a restrictive pattern was predominant. This study also observed that there was an increase in the number of gasoline pump attendants with declined lung function compared to the control group. Conclusion: Restrictive pattern of lung impairment was more predominant than the obstructive pattern among gasoline pump attendants. As a result, public health interventions should be instituted among these individuals, especially in developing countries.
文摘Background: Occupational health is an important consideration, especially for people that work in an environment with pollutants. Gasoline attendants are individuals that work in filling stations. They are constantly exposed to gasoline fumes and automobile engine products from vehicle exhaust. This increases the risk of acute and chronic respiratory diseases and carcinogenesis among them. The risk of health complications tends to increase with the duration of exposure. The study aimed to determine the proportion of gasoline attendants with lung function impairment. Methods and Materials: Two hundred and eight eligible participants were recruited for this study. A cross-sectional analytical study was carried out in Esan West local government area of Edo state, Nigeria. The study was carried out for a period of six months from December 2015 to May 2016. A questionnaire was used to obtain information on demographic characteristics, work history, mode of exposure and duration of exposure to petrol fumes. Lung function was assessed using a DTspiro spirometer (Model POP 10. Serial no 110843-005);also the anthropometric parameters of the respondent were measured. Statistical analysis was done using IBM SPSS version 20.0. Frequency and percentages were used to present categorical data. The mean and standard deviation of continuous variables were calculated and compared using the student’s t-test. The criteria of significant association were assumed for a p-value less than 0.05. Results: A total of one hundred and forty petrol pump attendants and one hundred and forty controls participated in this study. The mean age for petrol pump attendants was 24 ± 3.1 years and 23 ± 2.8 years for the control group. There were no significant differences in the gender distribution and anthropometric parameters as observed in this study. The lung impairment pattern observed in this study was obstructive in twelve (8.6%) gasoline pump attendants and restrictive pattern in thirty-nine (27.9%) gasoline pump attendants, while only four (2.9%) had an obstructive pattern and twelve (8.6%) had a restrictive pattern of lung impairment among the control group. This implies that a restrictive pattern was predominant. This study also observed that there was an increase in the number of gasoline pump attendants with declined lung function compared to the control group. Conclusion: Restrictive pattern of lung impairment was more predominant than the obstructive pattern among gasoline pump attendants. As a result, public health interventions should be instituted among these individuals, especially in developing countries.