There are three parts in this article. In Section 1, we establish the model of branching chain with drift in space-time random environment （BCDSTRE）, i.e., the coupling of branching chain and random walk. In Section...There are three parts in this article. In Section 1, we establish the model of branching chain with drift in space-time random environment （BCDSTRE）, i.e., the coupling of branching chain and random walk. In Section 2, we prove that any BCDSTRE must be a Markov chain in time random environment when we consider the distribution of the particles in space as a random element. In Section 3, we calculate the first-order moments and the second-order moments of BCDSTRE.展开更多
In this article, the dependent steps of a negative drift random walk are modelled as a two-sided linear process. Xn=-u＋∑j=-∞^∞ φn-jεj, where { ε, εn; -∞〈n〈＋∞} is a sequence of independent, identically di...In this article, the dependent steps of a negative drift random walk are modelled as a two-sided linear process. Xn=-u＋∑j=-∞^∞ φn-jεj, where { ε, εn; -∞〈n〈＋∞} is a sequence of independent, identically distributed random variables with zero mean, u 〉 0 is a constant and the coefficients {φi; -∞〈i〈∞} satisfy 0〈 ∑j=-∞^∞ ｜jφj｜〈 ∞ . Under the conditions that the distribution function of ｜ε｜ has dominated variation and ε satisfies certain tail balance conditions, the asymptotic behavior of P{sup n≥0 （-qu＋∑j=-∞^∞ εj βnj）〉x} is discussed. Then the result is applied to ultimate ruin probability.展开更多
Contaminants that are floating on the surface of the ocean are subjected to the action of random waves.In the literature,it has been asserted by researchers that the random wave action will lead to a dispersion mechan...Contaminants that are floating on the surface of the ocean are subjected to the action of random waves.In the literature,it has been asserted by researchers that the random wave action will lead to a dispersion mechanism through the induced Stokes drift,and that this dispersion mechanism may have the same order of significance comparable with the others means due to tidal currents and wind.It is investigated whether or not surface floating substances will disperse in the random wave environment due to the induced Stokes drift.An analytical derivation is first performed to obtain the drift velocity under the random waves.From the analysis,it is shown that the drift velocity is a time-independent value that does not possess any fluctuation given a specific wave energy spectrum.Thus,the random wave drift by itself should not have a dispersive effect on the surface floating substances.Experiments were then conducted with small floating objects subjected to P-M spectral waves in a laboratory wave flume,and the experimental results reinforced the conclusion drawn.展开更多
The large-scale development of electric vehicles(EVs)requires numerous charging stations to serve them,and the charging stations should be reasonably laid out and planned according to the charging demand of electric v...The large-scale development of electric vehicles(EVs)requires numerous charging stations to serve them,and the charging stations should be reasonably laid out and planned according to the charging demand of electric vehicles.Considering the costs of both operators and users,a site selection model for optimal layout planning of charging stations is constructed,and a queuing theory approach is used to determine the charging pile configuration to meet the charging demand in the planning area.To solve the difficulties of particle swarm global optimization search,the improved random drift particle swarm optimization(IRDPSO)and Voronoi diagram are used to jointly solve for the optimal layout of electric vehicles.The final arithmetic analysis verifies the feasibility and practicality of the model and algorithm,and the results show that the total social cost is minimized when the charging station is 9,the location of the charging station is close to the center of gravity and the layout is reasonable.展开更多
Laser ranging with frequency comb intermode beats[IMBs]has been suffering from random phase drifts[RPDs]for two decades.In this study,we reveal the influence of signal transmission path on the RPDs and propose a real-...Laser ranging with frequency comb intermode beats[IMBs]has been suffering from random phase drifts[RPDs]for two decades.In this study,we reveal the influence of signal transmission path on the RPDs and propose a real-time suppression method using two IMBs of similar frequencies from different combs.As the two IMBs obtain similar RPDs during their transmission through same signal paths,the RPD of the original probing signal IMB is suppressed by deducting the RPD of the newly added local IMB in real time.In our experiments,a real-time suppression of RPDs is achieved using IMBs of 1001 and 1000 MHz.For the sampling time of 100 s,the effect of 19-fold suppression has been achieved.The proposed method provides a new solution for the long-standing phase drift problem in laser ranging with comb IMBs.展开更多
基金Supported by the NSFC(10371092,11771185,10871200)
文摘There are three parts in this article. In Section 1, we establish the model of branching chain with drift in space-time random environment （BCDSTRE）, i.e., the coupling of branching chain and random walk. In Section 2, we prove that any BCDSTRE must be a Markov chain in time random environment when we consider the distribution of the particles in space as a random element. In Section 3, we calculate the first-order moments and the second-order moments of BCDSTRE.
基金Research supported by National Science Foundation of China (70671018 and 10371117)
文摘In this article, the dependent steps of a negative drift random walk are modelled as a two-sided linear process. Xn=-u＋∑j=-∞^∞ φn-jεj, where { ε, εn; -∞〈n〈＋∞} is a sequence of independent, identically distributed random variables with zero mean, u 〉 0 is a constant and the coefficients {φi; -∞〈i〈∞} satisfy 0〈 ∑j=-∞^∞ ｜jφj｜〈 ∞ . Under the conditions that the distribution function of ｜ε｜ has dominated variation and ε satisfies certain tail balance conditions, the asymptotic behavior of P{sup n≥0 （-qu＋∑j=-∞^∞ εj βnj）〉x} is discussed. Then the result is applied to ultimate ruin probability.
基金The State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering Research Foundation of China under contract No.2015491311
文摘Contaminants that are floating on the surface of the ocean are subjected to the action of random waves.In the literature,it has been asserted by researchers that the random wave action will lead to a dispersion mechanism through the induced Stokes drift,and that this dispersion mechanism may have the same order of significance comparable with the others means due to tidal currents and wind.It is investigated whether or not surface floating substances will disperse in the random wave environment due to the induced Stokes drift.An analytical derivation is first performed to obtain the drift velocity under the random waves.From the analysis,it is shown that the drift velocity is a time-independent value that does not possess any fluctuation given a specific wave energy spectrum.Thus,the random wave drift by itself should not have a dispersive effect on the surface floating substances.Experiments were then conducted with small floating objects subjected to P-M spectral waves in a laboratory wave flume,and the experimental results reinforced the conclusion drawn.
基金the National Social Science Foundation of China(No.18AJL014)。
文摘The large-scale development of electric vehicles(EVs)requires numerous charging stations to serve them,and the charging stations should be reasonably laid out and planned according to the charging demand of electric vehicles.Considering the costs of both operators and users,a site selection model for optimal layout planning of charging stations is constructed,and a queuing theory approach is used to determine the charging pile configuration to meet the charging demand in the planning area.To solve the difficulties of particle swarm global optimization search,the improved random drift particle swarm optimization(IRDPSO)and Voronoi diagram are used to jointly solve for the optimal layout of electric vehicles.The final arithmetic analysis verifies the feasibility and practicality of the model and algorithm,and the results show that the total social cost is minimized when the charging station is 9,the location of the charging station is close to the center of gravity and the layout is reasonable.
基金supported by the National Natural Science Foundation of China(NSFC)(Nos.52175501 and 51605120)the Heilongjiang Provincial Natural Science Foundation(No.LH2021E059)the National Key Research and Development Program of China(No.2020YFC2200204)。
文摘Laser ranging with frequency comb intermode beats[IMBs]has been suffering from random phase drifts[RPDs]for two decades.In this study,we reveal the influence of signal transmission path on the RPDs and propose a real-time suppression method using two IMBs of similar frequencies from different combs.As the two IMBs obtain similar RPDs during their transmission through same signal paths,the RPD of the original probing signal IMB is suppressed by deducting the RPD of the newly added local IMB in real time.In our experiments,a real-time suppression of RPDs is achieved using IMBs of 1001 and 1000 MHz.For the sampling time of 100 s,the effect of 19-fold suppression has been achieved.The proposed method provides a new solution for the long-standing phase drift problem in laser ranging with comb IMBs.
