Purpose-The purpose of this paper is to eliminate the fluctuations in train arrival and departure times caused by skewed distributions in interval operation times.These fluctuations arise from random origin and proces...Purpose-The purpose of this paper is to eliminate the fluctuations in train arrival and departure times caused by skewed distributions in interval operation times.These fluctuations arise from random origin and process factors during interval operations and can accumulate over multiple intervals.The aim is to enhance the robustness of high-speed rail station arrival and departure track utilization schemes.Design/methodologylapproach-To achieve this objective,the paper simulates actual train operations,incorporating the fluctuations in interval operation times into the utilization of arrival and departure tracks at the station.The Monte Carlo simulation method is adopted to solve this problem.This approach transforms a nonlinear model,which includes constraints from probability distribution functions and is difficult to solve directly,into a linear programming model that is easier to handle.The method then linearly weights two objectives to optimize the solution.Findings-Through the application of Monte Carlo simulation,the study successfully converts the complex nonlinear model with probability distribution function constraints into a manageable linear programming model.By continuously adjusting the weighting coefficients of the linear objectives,the method is able to optimize the Pareto solution.Notably,this approach does not require extensive scene data to obtain a satisfactory Pareto solution set.Originality/value-The paper contributes to the field by introducing a novel method for optimizing high-speed rail station arrival and departure track utilization in the presence of fluctuations in interval operation times.The use of Monte Carlo simulation to transform the problem into a tractable linear programming model represents a significant advancement.Furthermore,the method's ability to produce satisfactory Pareto solutions without relying on extensive data sets adds to its practical value and applicability in real-world scenarios.展开更多
The poor state of the environment,especially in urban areas,has become a major global issue,with developing countries such as Nigeria voicing growing concern.There is a scarcity of knowledge on the environmental impac...The poor state of the environment,especially in urban areas,has become a major global issue,with developing countries such as Nigeria voicing growing concern.There is a scarcity of knowledge on the environmental impact of PFSs as a result of the loss of life and property,as well as other serious socio-economic implications of non-compliance with PFSs siting criteria.The historical literature on the impact of residential buildings,the environment,and human health on PFSs in Nigeria,as well as the study’s gap,is examined in this research.It also outlines DPR compliance with PFSs location as well as established criteria for prohibiting PFS siting in Nigeria’s states.Relevant publications on PFSs-related topics were downloaded from Google Scholar.The goal of this study is to look back on a previous essay about PFSs in Nigeria and its impacts on the environment and human health.This study’s main purpose is to give a complete overview of Nigerian PFSs.According to the article analyzed,the majority of PFSs were located close to residents,with setbacks from the road and residential areas of less than 30 m in 90%of the filling stations.As a result,the landowners can band together to argue that a facility that is improperly sited cannot be built.A great deal of public participation is required.A campaign should be launched to raise awareness among filling station owners and other developers of the dangers of non-compliance with established norms.All violators of the established norms,as well as corrupt officials of enforcement agencies/bodies,should face open punishment so that others might learn their lessons.Finally,appropriate planning is required to allow future road expansion.展开更多
Terminal airspace(TMA)is the airspace centering several military and civil aviation airports with complex route structure,limited airspace resources,traffic flow,difficult management and considerable airspace complexi...Terminal airspace(TMA)is the airspace centering several military and civil aviation airports with complex route structure,limited airspace resources,traffic flow,difficult management and considerable airspace complexity.A scientific and rational sectorization of TMA can optimize airspace resources,and sufficiently utilize the control of human resources to ensure the safety of TMA.The functional sectorization model was established based on the route structure of arriving and departing aircraft as well as controlling requirements.Based on principles of sectorization and topological relations within a network,the arrival and departure sectorization model was established,using tree based ant colony algorithm(ACO)searching.Shanghai TMA was taken as an example to be sectorizaed,and the result showed that this model was superior to traditional ones when arrival and departure routes were separated at dense airport terminal airspace.展开更多
A high altitude platform station （HAPS） based communications scenario for providing Intemet access and broadband multimedia services to the passengers on board of a high speed train （traveling up to 300km/h） is pr...A high altitude platform station （HAPS） based communications scenario for providing Intemet access and broadband multimedia services to the passengers on board of a high speed train （traveling up to 300km/h） is proposed. Regarding the addressed scenario, when the propagation link between HAPS and train is blocked by obstacles, a three-dimensional （3-D） geometrical single cylinder spatial-temporal channel model is presented, in which closed form, mathematically tractable space-time correlation functions are obtained. It shows that the correlation functions determined by the 3-D model are of significant difference with those of the conventional 2-D model. Based on the analysis model, the paper derives a realized simulation model using sum-of-sinusoids approach, and applies method of equal areas （MEA） and modified method of equal areas （MMEA） to determine the model parameters. The fitting performance of the simulation model with the analysis one is evaluated by two means-square error （MSE） performance criteria. Finally, numerical simulation results verify the mathematical analysis conclusion, when N ≥21, simulation model has an excellent fitness with the analysis one.展开更多
为了探讨闪电探测站布局对闪电定位精度的影响,基于福建省九仙山自然闪电观测试验基地的磁场波形观测资料,选取探测站网内外不同方位和不同距离的10次地闪回击,以10站(或9站)同步的定位结果为基准,利用到达时间差法(Time of Arrival,TO...为了探讨闪电探测站布局对闪电定位精度的影响,基于福建省九仙山自然闪电观测试验基地的磁场波形观测资料,选取探测站网内外不同方位和不同距离的10次地闪回击,以10站(或9站)同步的定位结果为基准,利用到达时间差法(Time of Arrival,TOA),对比分析了任意5—8站不同测站组合情况下的定位结果差异性,并探讨定位差异性的可能原因。结果表明:闪电定位与测站数量和测站布局密切相关,同样的测站数量,不同测站布局的定位结果存在较大差异,而随着测站数量的增加,由测站布局不同所带来的差异性逐渐减小。相同的测站数量和布局,对不同方位距离闪电的定位偏差也存在明显不同。在测站网外围区域的闪电定位偏差明显大于网内,网外闪电定位结果往往呈现“带状分布”,距离测站网越远,这种“带状分布”的偏差分布越明显,这是由于双曲线交汇形成的狭长空间区域所致。展开更多
文摘Purpose-The purpose of this paper is to eliminate the fluctuations in train arrival and departure times caused by skewed distributions in interval operation times.These fluctuations arise from random origin and process factors during interval operations and can accumulate over multiple intervals.The aim is to enhance the robustness of high-speed rail station arrival and departure track utilization schemes.Design/methodologylapproach-To achieve this objective,the paper simulates actual train operations,incorporating the fluctuations in interval operation times into the utilization of arrival and departure tracks at the station.The Monte Carlo simulation method is adopted to solve this problem.This approach transforms a nonlinear model,which includes constraints from probability distribution functions and is difficult to solve directly,into a linear programming model that is easier to handle.The method then linearly weights two objectives to optimize the solution.Findings-Through the application of Monte Carlo simulation,the study successfully converts the complex nonlinear model with probability distribution function constraints into a manageable linear programming model.By continuously adjusting the weighting coefficients of the linear objectives,the method is able to optimize the Pareto solution.Notably,this approach does not require extensive scene data to obtain a satisfactory Pareto solution set.Originality/value-The paper contributes to the field by introducing a novel method for optimizing high-speed rail station arrival and departure track utilization in the presence of fluctuations in interval operation times.The use of Monte Carlo simulation to transform the problem into a tractable linear programming model represents a significant advancement.Furthermore,the method's ability to produce satisfactory Pareto solutions without relying on extensive data sets adds to its practical value and applicability in real-world scenarios.
文摘The poor state of the environment,especially in urban areas,has become a major global issue,with developing countries such as Nigeria voicing growing concern.There is a scarcity of knowledge on the environmental impact of PFSs as a result of the loss of life and property,as well as other serious socio-economic implications of non-compliance with PFSs siting criteria.The historical literature on the impact of residential buildings,the environment,and human health on PFSs in Nigeria,as well as the study’s gap,is examined in this research.It also outlines DPR compliance with PFSs location as well as established criteria for prohibiting PFS siting in Nigeria’s states.Relevant publications on PFSs-related topics were downloaded from Google Scholar.The goal of this study is to look back on a previous essay about PFSs in Nigeria and its impacts on the environment and human health.This study’s main purpose is to give a complete overview of Nigerian PFSs.According to the article analyzed,the majority of PFSs were located close to residents,with setbacks from the road and residential areas of less than 30 m in 90%of the filling stations.As a result,the landowners can band together to argue that a facility that is improperly sited cannot be built.A great deal of public participation is required.A campaign should be launched to raise awareness among filling station owners and other developers of the dangers of non-compliance with established norms.All violators of the established norms,as well as corrupt officials of enforcement agencies/bodies,should face open punishment so that others might learn their lessons.Finally,appropriate planning is required to allow future road expansion.
基金supported by the National Natural Science Foundation of China(Nos.U1233101,71271113)the Fundamental Research Funds for the Central Universities(No.NS2016062)
文摘Terminal airspace(TMA)is the airspace centering several military and civil aviation airports with complex route structure,limited airspace resources,traffic flow,difficult management and considerable airspace complexity.A scientific and rational sectorization of TMA can optimize airspace resources,and sufficiently utilize the control of human resources to ensure the safety of TMA.The functional sectorization model was established based on the route structure of arriving and departing aircraft as well as controlling requirements.Based on principles of sectorization and topological relations within a network,the arrival and departure sectorization model was established,using tree based ant colony algorithm(ACO)searching.Shanghai TMA was taken as an example to be sectorizaed,and the result showed that this model was superior to traditional ones when arrival and departure routes were separated at dense airport terminal airspace.
基金Supported by the National Natural Science Foundation of China (No. 60532030).
文摘A high altitude platform station （HAPS） based communications scenario for providing Intemet access and broadband multimedia services to the passengers on board of a high speed train （traveling up to 300km/h） is proposed. Regarding the addressed scenario, when the propagation link between HAPS and train is blocked by obstacles, a three-dimensional （3-D） geometrical single cylinder spatial-temporal channel model is presented, in which closed form, mathematically tractable space-time correlation functions are obtained. It shows that the correlation functions determined by the 3-D model are of significant difference with those of the conventional 2-D model. Based on the analysis model, the paper derives a realized simulation model using sum-of-sinusoids approach, and applies method of equal areas （MEA） and modified method of equal areas （MMEA） to determine the model parameters. The fitting performance of the simulation model with the analysis one is evaluated by two means-square error （MSE） performance criteria. Finally, numerical simulation results verify the mathematical analysis conclusion, when N ≥21, simulation model has an excellent fitness with the analysis one.
文摘为了探讨闪电探测站布局对闪电定位精度的影响,基于福建省九仙山自然闪电观测试验基地的磁场波形观测资料,选取探测站网内外不同方位和不同距离的10次地闪回击,以10站(或9站)同步的定位结果为基准,利用到达时间差法(Time of Arrival,TOA),对比分析了任意5—8站不同测站组合情况下的定位结果差异性,并探讨定位差异性的可能原因。结果表明:闪电定位与测站数量和测站布局密切相关,同样的测站数量,不同测站布局的定位结果存在较大差异,而随着测站数量的增加,由测站布局不同所带来的差异性逐渐减小。相同的测站数量和布局,对不同方位距离闪电的定位偏差也存在明显不同。在测站网外围区域的闪电定位偏差明显大于网内,网外闪电定位结果往往呈现“带状分布”,距离测站网越远,这种“带状分布”的偏差分布越明显,这是由于双曲线交汇形成的狭长空间区域所致。
