In this paper, some experimental studies on the impact of effluent from an exhaust tower of an underground tunnel with special construction are reported. By measuring the flow field downstream of the tower in NJU mete...In this paper, some experimental studies on the impact of effluent from an exhaust tower of an underground tunnel with special construction are reported. By measuring the flow field downstream of the tower in NJU meteorological wind tunnel, some flow characteristics in the make area were established. Based on these, an advanced random\|walk dispersion model was set up and applied successfully to the simulation of dispersion in the wake area. The modelling results were in accordance with wind tunnel measurements. The computed maximum of ground surface concentration in the building case was a factor of 3-4 higher than that in the flat case and appeared much closer to the source. The simulation indicated that random walk modelling is an effective and practical tool for the wake stream impact assessment.展开更多
Very recently, we have applied the random walk model to fit the global temperature anomaly, CRUTEM3. With encouraging results, we apply the random walk model to fit the temperature walk that is the conversion of recor...Very recently, we have applied the random walk model to fit the global temperature anomaly, CRUTEM3. With encouraging results, we apply the random walk model to fit the temperature walk that is the conversion of recorded tem-perature and real recorded temperature in 46 gamma world cities from 1901 to 1998 in this study. The results show that the random walk model can fit both temperature walk and real recorded temperature although the fitted results from other climate models are unavailable for comparison in these 46 cities. Therefore, the random walk model can fit not only the global temperature anomaly, but also the real recorded temperatures in various cities around the world.展开更多
To simulate the pollutant transport with seif-purification in inland waters,the widely used random walk model(RWM)is modified to include a source term for the degradation and to consider the impact of land boundaries....To simulate the pollutant transport with seif-purification in inland waters,the widely used random walk model(RWM)is modified to include a source term for the degradation and to consider the impact of land boundaries.The source term for the degradation is derived from the assumption of the first-order reaction kinetics.Parameters for the new model are determined by a comparison to the analytical results.The proposed model is then applied to simulate and analyze the transport of a test pollutant and its spatial distribution in a large reservoir in northeast China.Reasonable results are obtained,and the effects of the runoff,the flow structure,and the wind on the pollutant transport are analyzed.The results may help the risk assessment and the management of the water pollution in inland waters.展开更多
A numerical model has been developed to simulate the transport and fate of oil spilled at sea. The model combines the transport and fate processes of spilled oil with the random walk technique. Oil movement under th...A numerical model has been developed to simulate the transport and fate of oil spilled at sea. The model combines the transport and fate processes of spilled oil with the random walk technique. Oil movement under the influence of tidal currents, wind driven currents, and turbulent eddies is simulated by the PLUME RW dispersion model developed by HR Wallingford. The weathering processes in the model represent physical and chemical changes of soil slicks with time, and comprise mechanical spreading, dispersion, evaporation and emulsification. Shoreline stranding is determined approximately using a capacity method for different shoreline types. This paper presents details of the model, and describe the results of various sensitivity tests. The model is suitable for oil spill contingency planning.展开更多
According to random walk, in this paper, we propose a new traffic model for scheduling trains on a railway network. In the proposed method, using some iteration rules for walkers, the departure and the arrival times o...According to random walk, in this paper, we propose a new traffic model for scheduling trains on a railway network. In the proposed method, using some iteration rules for walkers, the departure and the arrival times of trains at each station are determined. We test the proposed method on an assumed railway network. The numerical simulations and the analytical results demonstrate that the proposed method provides an effective tool for scheduling trains. Some characteristic behaviours of train movement can be reproduced, such as train delay.展开更多
A novel immunization strategy called the random walk immunization strategy on scale-free networks is proposed. Different from other known immunization strategies, this strategy works as follows： a node is randomly ch...A novel immunization strategy called the random walk immunization strategy on scale-free networks is proposed. Different from other known immunization strategies, this strategy works as follows： a node is randomly chosen from the network. Starting from this node, randomly walk to one of its neighbor node; if the present node is not immunized, then immunize it and continue the random walk; otherwise go back to the previous node and randomly walk again. This process is repeated until a certain fraction of nodes is immunized. By theoretical analysis and numerical simulations, we found that this strategy is very effective in comparison with the other known immunization strategies.展开更多
It is presented here a continuous time random walk model for diffusion mediated reactions with both species mobile. The random walk is carried out over an infinite homogeneouos lattice. They are calculated the probabi...It is presented here a continuous time random walk model for diffusion mediated reactions with both species mobile. The random walk is carried out over an infinite homogeneouos lattice. They are calculated the probability density for the time of reaction of a pair, the reaction rate and the time evolution of the concentration of the majority species. Analytical results are obtained in the Fourier-Laplace transform representation. Known results for a fixed trap are reobtained with appropriate marginal probabilities. It is thus justified Smoluchowski’s original approximation considering the trap at a fixed position and the majority species diffusing with a coefficient sum of the individual coefficients. The results obtained are illustrated by a one dimensional model with bias.展开更多
This paper deals with a stochastic representation of the rainfall process. The analysis of a rainfall time series shows that cumulative representation of a rainfall time series can be modeled as a non-Gaussian random ...This paper deals with a stochastic representation of the rainfall process. The analysis of a rainfall time series shows that cumulative representation of a rainfall time series can be modeled as a non-Gaussian random walk with a log-normal jump distribution and a time-waiting distribution following a tempered a-stable probability law. Based on the random walk model, a fractional Fokker-Planck equation （FFPE） with tempered a-stable waiting times was obtained. Through the comparison of observed data and simulated results from the random walk model and FFPE model with tempered a-stable waiting times, it can be concluded that the behavior of the rainfall process is globally reproduced, and the FFPE model with tempered a-stable waiting times is more efficient in reproducing the observed behavior.展开更多
Stock market trading is an activity in which investors need fast and accurate information to make effective decisions.But the fact is that forecasting stock prices by using various models has been suffering from low a...Stock market trading is an activity in which investors need fast and accurate information to make effective decisions.But the fact is that forecasting stock prices by using various models has been suffering from low accuracy,slow convergence,and complex parameters.This study aims to employ a mixed model to improve the accuracy of stock price prediction.We present how to use a random walk based on jump-diffusion,to obtain stock predictions with a good-fitting degree by adjusting different parameters.Aimed at getting better parameters and then using the time series model to predict the data,we employed the time series model to smooth the sequence utilizing logarithm and difference,which successfully resulted in drawing the auto-correlation figure and partial the auto-correlation figure.According to the comparative analysis,which focuses on checking the mean absolute error,including root mean square error and R square evaluation index,we have drawn a clear conclusion that our mixed model prediction effect is relatively good.In the context of Chinese stocks,the hybrid random walk model is very suitable for predicting stocks.It can“interpret”the randomness of stocks very well,and it also has an unparalleled prediction effect compared with other models.Based on the time series model’s application in this paper,the abovementioned series is more suitable for predicting trends.展开更多
全球导航卫星系统GNSS对流层天顶湿延迟(zenith wet delay,ZWD)随机噪声不仅影响ZWD估计值大小,还会影响ZWD的趋势项变化。为揭示ZWD随机游走过程噪声(random walk process noise,RWPN)的时空变化特征,本文选取全球20个IGS(Internationa...全球导航卫星系统GNSS对流层天顶湿延迟(zenith wet delay,ZWD)随机噪声不仅影响ZWD估计值大小,还会影响ZWD的趋势项变化。为揭示ZWD随机游走过程噪声(random walk process noise,RWPN)的时空变化特征,本文选取全球20个IGS(International GNSS Service)测站,基于JPL(Jet Propulsion Laboratory)、GFZ(Helmholtz-Centre Potsdam-German Research Centre for Geosciences)和CODE(Center for Orbit Determination in Europe)分析中心2010至2020年对流层产品,从不同地理位置和不同时间序列分析GNSS ZWD随机游走过程噪声的变化范围和特征;并且在扣除ZWD的趋势项和主要周期项后,进一步揭示了ZWD残差信号分量构成。结果表明:不同地理位置湿延迟RWPN具有显著差异,年均值范围在0.01~0.146 mm/√s之间,且在大气集中的中低纬地区湿延迟RWPN值较大,在大气相对稀薄的极地地区其值较小;同一测站的湿延迟RWPN具有明显的周年、半周年和季节性特征,极差值高达0.12 mm/√s以上;通过对ZWD残差值分析,发现ZWD残差信号除包含白噪声外,还具有4.8 h至2.43 d的高频信号分量。展开更多
The suitability of models for describing the clonal growth of Trifolium repens population was discussed. The results showed that deterministic models were inadequate for describing its clonal growth, but the diffusion...The suitability of models for describing the clonal growth of Trifolium repens population was discussed. The results showed that deterministic models were inadequate for describing its clonal growth, but the diffusion models and the randomwalk models suited for the clonal growth characteristics of the population. And it was found that random-walk models were better than diffusion models for describing a population in an environment with rich natural resources, and the latter was better in a poor environment.展开更多
On the basis of data mining,systematic pharmacology,molecular docking,and experiment validation,the oxidative-inflammatory molecular targets of Coicis Semen in the therapy of osteoarthritis(OA)were explored.Methods:Th...On the basis of data mining,systematic pharmacology,molecular docking,and experiment validation,the oxidative-inflammatory molecular targets of Coicis Semen in the therapy of osteoarthritis(OA)were explored.Methods:The association rule analysis was effectively applied to highlight the correlation between Coicis Semen and oxidative inflammation indices.The random walk model was subsequently used to evaluate the clinical efficacy of Coicis Semen.Network pharmacology was used to predict network targets.The binding affinity of the active ingredient in Coicis Semen to the key target of OA was also successfully predicted.Results:Coicis Semen showed a significant reduction in oxidative-inflammatory indicators of OA.A total of 108 promising targets were predicted for the 24 bioactive compounds in Coicis Semen.Eight target genes were considered core target genes.The enrichment analysis predicts that Coicis Semen may activate the interleukin(IL)-17,mitogen-activated protein kinase(MAPK),and nuclear factor kappa B(NF-kappa B)signaling pathways.Molecular docking demonstrated that stigmasterol,2-monoolein,sitosterol,and sitosterol alpha1 had free binding energies to oxidative and inflammatory targets(MAPK1,Estrogen Receptor 1[ESR1],and Peroxisome Proliferator-Activated Receptor Alpha[PPARA]).Both clinical trials and in vitro cell experiments revealed that Coicis Semen could increase ESR1 and PPAR-αlevels while decreasing MAPK1 levels.Conclusions:Coicis Semen has a remarkable anti-OA effect.Precisely,the major components of Coicis Semen,including stigmasterol,sitosterol alpha1,sitosterol,and 2-monoolein,specifically inhibit MAPK1,ESR1,and PPARA to reduce the inflammatory response and oxidative damage in OA.展开更多
文摘In this paper, some experimental studies on the impact of effluent from an exhaust tower of an underground tunnel with special construction are reported. By measuring the flow field downstream of the tower in NJU meteorological wind tunnel, some flow characteristics in the make area were established. Based on these, an advanced random\|walk dispersion model was set up and applied successfully to the simulation of dispersion in the wake area. The modelling results were in accordance with wind tunnel measurements. The computed maximum of ground surface concentration in the building case was a factor of 3-4 higher than that in the flat case and appeared much closer to the source. The simulation indicated that random walk modelling is an effective and practical tool for the wake stream impact assessment.
文摘Very recently, we have applied the random walk model to fit the global temperature anomaly, CRUTEM3. With encouraging results, we apply the random walk model to fit the temperature walk that is the conversion of recorded tem-perature and real recorded temperature in 46 gamma world cities from 1901 to 1998 in this study. The results show that the random walk model can fit both temperature walk and real recorded temperature although the fitted results from other climate models are unavailable for comparison in these 46 cities. Therefore, the random walk model can fit not only the global temperature anomaly, but also the real recorded temperatures in various cities around the world.
基金Supported by the National Key Research and Development Program of China(Grant No.2018 YFC0407803)the National Natural Science Foundation of China(Grant No.51679009).
文摘To simulate the pollutant transport with seif-purification in inland waters,the widely used random walk model(RWM)is modified to include a source term for the degradation and to consider the impact of land boundaries.The source term for the degradation is derived from the assumption of the first-order reaction kinetics.Parameters for the new model are determined by a comparison to the analytical results.The proposed model is then applied to simulate and analyze the transport of a test pollutant and its spatial distribution in a large reservoir in northeast China.Reasonable results are obtained,and the effects of the runoff,the flow structure,and the wind on the pollutant transport are analyzed.The results may help the risk assessment and the management of the water pollution in inland waters.
文摘A numerical model has been developed to simulate the transport and fate of oil spilled at sea. The model combines the transport and fate processes of spilled oil with the random walk technique. Oil movement under the influence of tidal currents, wind driven currents, and turbulent eddies is simulated by the PLUME RW dispersion model developed by HR Wallingford. The weathering processes in the model represent physical and chemical changes of soil slicks with time, and comprise mechanical spreading, dispersion, evaporation and emulsification. Shoreline stranding is determined approximately using a capacity method for different shoreline types. This paper presents details of the model, and describe the results of various sensitivity tests. The model is suitable for oil spill contingency planning.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 60634010 and 60776829)the New Century Excellent Talents in University (Grant No. NCET-06-0074)the State Key Laboratory of Rail Traffic Control and Safety,Beijing Jiaotong University (Grant No. RCS2008ZZ001)
文摘According to random walk, in this paper, we propose a new traffic model for scheduling trains on a railway network. In the proposed method, using some iteration rules for walkers, the departure and the arrival times of trains at each station are determined. We test the proposed method on an assumed railway network. The numerical simulations and the analytical results demonstrate that the proposed method provides an effective tool for scheduling trains. Some characteristic behaviours of train movement can be reproduced, such as train delay.
基金supported by the National Natural Science Foundation of China (No.60774088)the Program for New Century Excellent Talents in University of China (No.NCET-2005-229)the Science and Technology Research Key Project of Education Ministry of China (No.107024)
文摘A novel immunization strategy called the random walk immunization strategy on scale-free networks is proposed. Different from other known immunization strategies, this strategy works as follows： a node is randomly chosen from the network. Starting from this node, randomly walk to one of its neighbor node; if the present node is not immunized, then immunize it and continue the random walk; otherwise go back to the previous node and randomly walk again. This process is repeated until a certain fraction of nodes is immunized. By theoretical analysis and numerical simulations, we found that this strategy is very effective in comparison with the other known immunization strategies.
文摘It is presented here a continuous time random walk model for diffusion mediated reactions with both species mobile. The random walk is carried out over an infinite homogeneouos lattice. They are calculated the probability density for the time of reaction of a pair, the reaction rate and the time evolution of the concentration of the majority species. Analytical results are obtained in the Fourier-Laplace transform representation. Known results for a fixed trap are reobtained with appropriate marginal probabilities. It is thus justified Smoluchowski’s original approximation considering the trap at a fixed position and the majority species diffusing with a coefficient sum of the individual coefficients. The results obtained are illustrated by a one dimensional model with bias.
文摘This paper deals with a stochastic representation of the rainfall process. The analysis of a rainfall time series shows that cumulative representation of a rainfall time series can be modeled as a non-Gaussian random walk with a log-normal jump distribution and a time-waiting distribution following a tempered a-stable probability law. Based on the random walk model, a fractional Fokker-Planck equation （FFPE） with tempered a-stable waiting times was obtained. Through the comparison of observed data and simulated results from the random walk model and FFPE model with tempered a-stable waiting times, it can be concluded that the behavior of the rainfall process is globally reproduced, and the FFPE model with tempered a-stable waiting times is more efficient in reproducing the observed behavior.
基金supported by the 2020 Hunan Natural Science Foundation Project"Research on the Key Technologies of a Personalized Learning Platform for Higher Vocational Students Based on Self-Expanding Knowledge Base and Multimodal Portraits"(2020JJ7041)partly supported by the National Natural Science Foundation of China(No.72073041).
文摘Stock market trading is an activity in which investors need fast and accurate information to make effective decisions.But the fact is that forecasting stock prices by using various models has been suffering from low accuracy,slow convergence,and complex parameters.This study aims to employ a mixed model to improve the accuracy of stock price prediction.We present how to use a random walk based on jump-diffusion,to obtain stock predictions with a good-fitting degree by adjusting different parameters.Aimed at getting better parameters and then using the time series model to predict the data,we employed the time series model to smooth the sequence utilizing logarithm and difference,which successfully resulted in drawing the auto-correlation figure and partial the auto-correlation figure.According to the comparative analysis,which focuses on checking the mean absolute error,including root mean square error and R square evaluation index,we have drawn a clear conclusion that our mixed model prediction effect is relatively good.In the context of Chinese stocks,the hybrid random walk model is very suitable for predicting stocks.It can“interpret”the randomness of stocks very well,and it also has an unparalleled prediction effect compared with other models.Based on the time series model’s application in this paper,the abovementioned series is more suitable for predicting trends.
文摘全球导航卫星系统GNSS对流层天顶湿延迟(zenith wet delay,ZWD)随机噪声不仅影响ZWD估计值大小,还会影响ZWD的趋势项变化。为揭示ZWD随机游走过程噪声(random walk process noise,RWPN)的时空变化特征,本文选取全球20个IGS(International GNSS Service)测站,基于JPL(Jet Propulsion Laboratory)、GFZ(Helmholtz-Centre Potsdam-German Research Centre for Geosciences)和CODE(Center for Orbit Determination in Europe)分析中心2010至2020年对流层产品,从不同地理位置和不同时间序列分析GNSS ZWD随机游走过程噪声的变化范围和特征;并且在扣除ZWD的趋势项和主要周期项后,进一步揭示了ZWD残差信号分量构成。结果表明:不同地理位置湿延迟RWPN具有显著差异,年均值范围在0.01~0.146 mm/√s之间,且在大气集中的中低纬地区湿延迟RWPN值较大,在大气相对稀薄的极地地区其值较小;同一测站的湿延迟RWPN具有明显的周年、半周年和季节性特征,极差值高达0.12 mm/√s以上;通过对ZWD残差值分析,发现ZWD残差信号除包含白噪声外,还具有4.8 h至2.43 d的高频信号分量。
文摘The suitability of models for describing the clonal growth of Trifolium repens population was discussed. The results showed that deterministic models were inadequate for describing its clonal growth, but the diffusion models and the randomwalk models suited for the clonal growth characteristics of the population. And it was found that random-walk models were better than diffusion models for describing a population in an environment with rich natural resources, and the latter was better in a poor environment.
基金supported by the Anhui Famous Traditional Chinese Medicine Liu Jian Studio Construction Project(Traditional Chinese Medicine Development Secret[2018]No.11)the Ministry of Science and Technology National Key Research and Development Program Chinese Medicine Modernization Research Key Project(No.2018YFC1705204)+2 种基金Anhui Province Traditional Chinese Medicine Leading Talent Project(Traditional Chinese Medicine Development Secret[2018]No.23)the Anhui key Research and Development Program Foreign Science and Technology Cooperation Project(No.201904b11020011)the Anhui Provincial Education Department Project(No.2022AH050449).
文摘On the basis of data mining,systematic pharmacology,molecular docking,and experiment validation,the oxidative-inflammatory molecular targets of Coicis Semen in the therapy of osteoarthritis(OA)were explored.Methods:The association rule analysis was effectively applied to highlight the correlation between Coicis Semen and oxidative inflammation indices.The random walk model was subsequently used to evaluate the clinical efficacy of Coicis Semen.Network pharmacology was used to predict network targets.The binding affinity of the active ingredient in Coicis Semen to the key target of OA was also successfully predicted.Results:Coicis Semen showed a significant reduction in oxidative-inflammatory indicators of OA.A total of 108 promising targets were predicted for the 24 bioactive compounds in Coicis Semen.Eight target genes were considered core target genes.The enrichment analysis predicts that Coicis Semen may activate the interleukin(IL)-17,mitogen-activated protein kinase(MAPK),and nuclear factor kappa B(NF-kappa B)signaling pathways.Molecular docking demonstrated that stigmasterol,2-monoolein,sitosterol,and sitosterol alpha1 had free binding energies to oxidative and inflammatory targets(MAPK1,Estrogen Receptor 1[ESR1],and Peroxisome Proliferator-Activated Receptor Alpha[PPARA]).Both clinical trials and in vitro cell experiments revealed that Coicis Semen could increase ESR1 and PPAR-αlevels while decreasing MAPK1 levels.Conclusions:Coicis Semen has a remarkable anti-OA effect.Precisely,the major components of Coicis Semen,including stigmasterol,sitosterol alpha1,sitosterol,and 2-monoolein,specifically inhibit MAPK1,ESR1,and PPARA to reduce the inflammatory response and oxidative damage in OA.
