This paper is concerned with a three-species competitive model with both white noises and Levy noises. We first carry out the almost complete parameters analysis for the model and establish the critical value between ...This paper is concerned with a three-species competitive model with both white noises and Levy noises. We first carry out the almost complete parameters analysis for the model and establish the critical value between persistence in the mean and extinction for each species. The sufficient criteria for stability in distribution of solutions are obtained. Finally, numerical simulations are carried out to verify the theoretical results.展开更多
The aim of the article is to propose the method of designing double regulation control valves used in heating installations, allowing to obtain a constant value of the so-called inner authority and thus the constancy ...The aim of the article is to propose the method of designing double regulation control valves used in heating installations, allowing to obtain a constant value of the so-called inner authority and thus the constancy of the valve control characteristic, regardless of the pre-setting value set on the valve. The shape of the valve's regulation characteristics is one of the main factors determining the quality of the quantitative regulation, and thus the stability of the system's operation and overall operating costs. For this reason, the issue discussed in the article is important and can be applied in practical implementations of the valve sizing and the valve selection. The analysis was based on the relations binding the hydraulic resistances occurring inside the control valve, and the corresponding flow factors, using original author's proposal. The experimental verification was performed on a special measuring stand prepared for this purpose, measuring the values of the medium volume flow at a constant differential pressure, and then the results were converted into values of the flow factor, used in the proposed mathematical model. The results confirm the thesis put forward and the proposed mathematical model. High convergence of the results of experimental verification with the proposed mathematical model was obtained.展开更多
基金The work is supported by National Science Foundation of China （No. 11472298）, the Fundamental Research Funds for the Central Universities （No. ZXH2012K004）, the National Science Foundation of Tianjin City （No. 13JCQNJC04400） and the NNSF of P. R. China （No. 11401574）.
文摘This paper is concerned with a three-species competitive model with both white noises and Levy noises. We first carry out the almost complete parameters analysis for the model and establish the critical value between persistence in the mean and extinction for each species. The sufficient criteria for stability in distribution of solutions are obtained. Finally, numerical simulations are carried out to verify the theoretical results.
文摘The aim of the article is to propose the method of designing double regulation control valves used in heating installations, allowing to obtain a constant value of the so-called inner authority and thus the constancy of the valve control characteristic, regardless of the pre-setting value set on the valve. The shape of the valve's regulation characteristics is one of the main factors determining the quality of the quantitative regulation, and thus the stability of the system's operation and overall operating costs. For this reason, the issue discussed in the article is important and can be applied in practical implementations of the valve sizing and the valve selection. The analysis was based on the relations binding the hydraulic resistances occurring inside the control valve, and the corresponding flow factors, using original author's proposal. The experimental verification was performed on a special measuring stand prepared for this purpose, measuring the values of the medium volume flow at a constant differential pressure, and then the results were converted into values of the flow factor, used in the proposed mathematical model. The results confirm the thesis put forward and the proposed mathematical model. High convergence of the results of experimental verification with the proposed mathematical model was obtained.
