Accuracy and roughness, proposed by Pawlak(1982), might draw a conclusion inconsistent with our intuition in some cases. This letter analyzes the limitations in these measures and proposes improved accuracy and roughn...Accuracy and roughness, proposed by Pawlak(1982), might draw a conclusion inconsistent with our intuition in some cases. This letter analyzes the limitations in these measures and proposes improved accuracy and roughness measures based on information theory.展开更多
Long memory is an important phenomenon that arises sometimes in the analysis of time series or spatial data.Most of the definitions concerning the long memory of a stationary process are based on the second-order prop...Long memory is an important phenomenon that arises sometimes in the analysis of time series or spatial data.Most of the definitions concerning the long memory of a stationary process are based on the second-order properties of the process.The mutual information between the past and future I_(p−f) of a stationary process represents the information stored in the history of the process which can be used to predict the future.We suggest that a stationary process can be referred to as long memory if its I_(p−f) is infinite.For a stationary process with finite block entropy,I_(p−f) is equal to the excess entropy,which is the summation of redundancies that relate the convergence rate of the conditional(differential)entropy to the entropy rate.Since the definitions of the I_(p−f) and the excess entropy of a stationary process require a very weak moment condition on the distribution of the process,it can be applied to processes whose distributions are without a bounded second moment.A significant property of I_(p−f) is that it is invariant under one-to-one transformation;this enables us to know the I_(p−f) of a stationary process from other processes.For a stationary Gaussian process,the long memory in the sense of mutual information is more strict than that in the sense of covariance.We demonstrate that the I_(p−f) of fractional Gaussian noise is infinite if and only if the Hurst parameter is H∈(1/2,1).展开更多
The application of the excess entropy scaling(EES)method to predict the viscosity,thermal conductivity and thermal diffusivity of HFC/HFO refrigerants is evaluated in this paper.The universal coefficients of the EES m...The application of the excess entropy scaling(EES)method to predict the viscosity,thermal conductivity and thermal diffusivity of HFC/HFO refrigerants is evaluated in this paper.The universal coefficients of the EES model were firstly obtained from the properties of HFC refrigerants,and the accuracy of the model was further investigated with HFO properties.It was suggested that the EES model correlated the viscosity very well with the average absolute deviations(AADs)of most HFC refrigerants lower than 6.55%except R32.The correlations also provided very good prediction on the viscosity for R1234yf and R1234ze(E),but not for R1336mzz(Z).The prediction of thermal conductivity for both HFC and HFO refrigerants was generally well with the maximum AAD of 11.44%.However,the paper also indicated that there were no universal thermal diffusivity coefficients for even HFC refrigerants,and the linear function could not fit the thermal diffusivity curve very well.Therefore,the exclusively two-order polynomial correlations based on the EES model were presented for each HFC/HFO refrigerant.展开更多
Based on the theory of non-equilibrium thermodynamics, considering the dynamic effect of molecular diffusion and the change in thermodynamic parameters caused by wax precipitation, the phenomenological relations of di...Based on the theory of non-equilibrium thermodynamics, considering the dynamic effect of molecular diffusion and the change in thermodynamic parameters caused by wax precipitation, the phenomenological relations of different thermodynamic "force" and "flow" interactions were derived. The corresponding thermodynamic model of a waxy crude oil pipeline transportation system was built, and then, the excess entropy production expression was proposed. Furthermore, the stability criterion model of the pipeline transportation system was established on the basis of Lyapounov stability theory. Taking the oil pipeline in Daqing oilfield as an example, based on the four parameters of out-station temperature, out-station pressure, flow rate and water content, the stable and unstable regions of the system were divided, and the formation mechanisms of the two different regions were analyzed. The experimental loop device of wax deposition rate was designed, and then, the wax deposition rate under the four parameters was measured. The results showed that the stable region of the wax deposition rate fluctuation was basically in accordance with the stability region analyzed by the criterion model established in this paper, which proved that the stability criterion model was feasible for analyzing the stability of the waxy crude oil pipeline transportation process.展开更多
The paper targets a future world where all wireless networks are self-organising entities and in which the predominant mode of spectrum access is dynamic. The paper explores whether the behaviour of a collection of au...The paper targets a future world where all wireless networks are self-organising entities and in which the predominant mode of spectrum access is dynamic. The paper explores whether the behaviour of a collection of autonomous self-organising wireless systems can be treated as a complex system and whether complex systems science can shed light on the design and deployment of these networks. The authors focus on networks that self-organise from a frequency perspective to understand the behaviour of a collection of wireless self-organising nodes. Each autonomous network is modelled as a cell in a lattice and follows a simple set of self-organisation rules. Two scenarios are considered, one in which each cell is based on cellular automata and which provides an abstracted view of interference and a second in which each cell uses a self-organising technique which more accurately accounts for interference. The authors use excess entropy to measure complexity and in combination with entropy gain an understanding of the structure emerging in the lattice for the self-organising networks. The authors show that the self-organising systems presented here do exhibit complex behaviour. Finally,the authors look at the robustness of these complex systems and show that they are robust against changes in the environment.展开更多
基金National Natural Science Foundation of China(60073012)Natural Sceience Foundation of Jiangsu, China(BK2001004)Visiting Scholar Foundation of Key Lab in Wuhan University
文摘Accuracy and roughness, proposed by Pawlak(1982), might draw a conclusion inconsistent with our intuition in some cases. This letter analyzes the limitations in these measures and proposes improved accuracy and roughness measures based on information theory.
基金supported by the Scientific Research Foundation for the Returned Overseas Chinese Scholars of State Education Ministry,the Key Scientific Research Project of Hunan Provincial Education Department (19A342)the National Natural Science Foundation of China (11671132,61903309 and 12271418)+2 种基金the National Key Research and Development Program of China (2020YFA0714200)Sichuan Science and Technology Program (2023NSFSC1355)the Applied Economics of Hunan Province.
文摘Long memory is an important phenomenon that arises sometimes in the analysis of time series or spatial data.Most of the definitions concerning the long memory of a stationary process are based on the second-order properties of the process.The mutual information between the past and future I_(p−f) of a stationary process represents the information stored in the history of the process which can be used to predict the future.We suggest that a stationary process can be referred to as long memory if its I_(p−f) is infinite.For a stationary process with finite block entropy,I_(p−f) is equal to the excess entropy,which is the summation of redundancies that relate the convergence rate of the conditional(differential)entropy to the entropy rate.Since the definitions of the I_(p−f) and the excess entropy of a stationary process require a very weak moment condition on the distribution of the process,it can be applied to processes whose distributions are without a bounded second moment.A significant property of I_(p−f) is that it is invariant under one-to-one transformation;this enables us to know the I_(p−f) of a stationary process from other processes.For a stationary Gaussian process,the long memory in the sense of mutual information is more strict than that in the sense of covariance.We demonstrate that the I_(p−f) of fractional Gaussian noise is infinite if and only if the Hurst parameter is H∈(1/2,1).
基金sponsored by the following research grants:National Science Foundation of China(No 51906216)。
文摘The application of the excess entropy scaling(EES)method to predict the viscosity,thermal conductivity and thermal diffusivity of HFC/HFO refrigerants is evaluated in this paper.The universal coefficients of the EES model were firstly obtained from the properties of HFC refrigerants,and the accuracy of the model was further investigated with HFO properties.It was suggested that the EES model correlated the viscosity very well with the average absolute deviations(AADs)of most HFC refrigerants lower than 6.55%except R32.The correlations also provided very good prediction on the viscosity for R1234yf and R1234ze(E),but not for R1336mzz(Z).The prediction of thermal conductivity for both HFC and HFO refrigerants was generally well with the maximum AAD of 11.44%.However,the paper also indicated that there were no universal thermal diffusivity coefficients for even HFC refrigerants,and the linear function could not fit the thermal diffusivity curve very well.Therefore,the exclusively two-order polynomial correlations based on the EES model were presented for each HFC/HFO refrigerant.
基金financially supported by the National Natural Science Foundation of China (51534004)the Northeast Petroleum University “National Fund” Cultivation Fund (2017PYZL-07)
文摘Based on the theory of non-equilibrium thermodynamics, considering the dynamic effect of molecular diffusion and the change in thermodynamic parameters caused by wax precipitation, the phenomenological relations of different thermodynamic "force" and "flow" interactions were derived. The corresponding thermodynamic model of a waxy crude oil pipeline transportation system was built, and then, the excess entropy production expression was proposed. Furthermore, the stability criterion model of the pipeline transportation system was established on the basis of Lyapounov stability theory. Taking the oil pipeline in Daqing oilfield as an example, based on the four parameters of out-station temperature, out-station pressure, flow rate and water content, the stable and unstable regions of the system were divided, and the formation mechanisms of the two different regions were analyzed. The experimental loop device of wax deposition rate was designed, and then, the wax deposition rate under the four parameters was measured. The results showed that the stable region of the wax deposition rate fluctuation was basically in accordance with the stability region analyzed by the criterion model established in this paper, which proved that the stability criterion model was feasible for analyzing the stability of the waxy crude oil pipeline transportation process.
基金support by the Irish CTVR CSET under Grant No.10/CE/I1853
文摘The paper targets a future world where all wireless networks are self-organising entities and in which the predominant mode of spectrum access is dynamic. The paper explores whether the behaviour of a collection of autonomous self-organising wireless systems can be treated as a complex system and whether complex systems science can shed light on the design and deployment of these networks. The authors focus on networks that self-organise from a frequency perspective to understand the behaviour of a collection of wireless self-organising nodes. Each autonomous network is modelled as a cell in a lattice and follows a simple set of self-organisation rules. Two scenarios are considered, one in which each cell is based on cellular automata and which provides an abstracted view of interference and a second in which each cell uses a self-organising technique which more accurately accounts for interference. The authors use excess entropy to measure complexity and in combination with entropy gain an understanding of the structure emerging in the lattice for the self-organising networks. The authors show that the self-organising systems presented here do exhibit complex behaviour. Finally,the authors look at the robustness of these complex systems and show that they are robust against changes in the environment.