We report on the investigation of intermode beating mode-locked(IBML)pulse generation in a simple all-fiber Tm^3+-doped double clad fiber laser(TDFL).This IBML TDFL is implemented by matching longitudinal-mode frequen...We report on the investigation of intermode beating mode-locked(IBML)pulse generation in a simple all-fiber Tm^3+-doped double clad fiber laser(TDFL).This IBML TDFL is implemented by matching longitudinal-mode frequency between 793 nm laser and TDFL without extra mode locker.The central wavelength of 1983 nm,the fundamental pulse frequency of 9.6 MHz and the signal-to-noise ratio(SNR)of>50 dB are achieved in this IBML TDFL.With laser cavity optimization,the IBML TDFL can finally generate an average output power of 1.03 W with corresponding pulse energy of 107 nJ.These results can provide an easily accessible way to develop compact large-energy,highpower TDFLs.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
The evolution mechanism of railway transportation network nodes driven by sea-rail intermodal transport(SRIT),a globally prevalent logistics method,has not been thoroughly investigated.From the perspective of SRIT,thi...The evolution mechanism of railway transportation network nodes driven by sea-rail intermodal transport(SRIT),a globally prevalent logistics method,has not been thoroughly investigated.From the perspective of SRIT,this study constructed a framework for understanding the evolution of railway container transport network nodes using Northeast China from 2013 to 2020 as a case study.It leverages proprietary data from 95306 Railway Freight E-commerce Platform.By employing the hybrid EWM-GA-TOPSIS model,complex network analysis,modified gravity model,and correlation and regression analyses,this study delves into the spatiotemporal patterns and dynamic transformations of railway container freight stations(RCFS).Finally,the long-term relationship between the RCFS and SRIT is explored.The results indicate that the spatial and temporal analysis of the RCFS in Northeast China from 2013 to 2020 revealed a clear polarisation trend,with the top-ranked stations mainly concentrated near ports and important transportation hubs.Additionally,the RCFS exhibited an expansionary trend;however,its development was uneven,and there was a significant increase in the number of new stations compared to abandoned stations,indicating an overall positive growth tendency.Moreover,the intensity of the SRIT at the RCFS in Northeast China notably increased.A significant positive linear relationship exists between SRIT and the freight capacity of all stations.A relatively pronounced correlation was observed for high-intensity stations,whereas a relatively weak correlation was observed for low-intensity stations.This study not only provides an effective framework for future research on RCFS within the context of SRIT but also serves as a scientific reference for promoting the implementation of the national strategy for multimodal transportation.展开更多
The lack of adequate and modern transport infrastructures makes the cost of transport in Africa higher than the rest of the world. Most of the transport infrastructures that exist were constructed during the colonial ...The lack of adequate and modern transport infrastructures makes the cost of transport in Africa higher than the rest of the world. Most of the transport infrastructures that exist were constructed during the colonial era which makes inter-regional connectivity difficult. The African Union in collaboration with other organization has committed to bridge the transport gap in Africa but still, face some challenges. This paper discusses the main issues that contribute for the weak nature of transportation in Sub-Saharan Africa with regards to the main transport modes and seeks to establish the possibility of sustainable intermodal transport through the integration of the different transport modes. Some policy reforms and other bilateral agreements such as deregulating the transport markets in West and Central Africa have been suggested to facilitate the development of an effective and efficient transport network in the Sub-Saharan African region.展开更多
The purpose of this paper is to explore the development process of a large scale dry port and to analyse what measures and actions are needed in order to support the decision making process and ensure an effective and...The purpose of this paper is to explore the development process of a large scale dry port and to analyse what measures and actions are needed in order to support the decision making process and ensure an effective and efficient dry port that serves the City and the region’s current and future needs. The purpose is explored in the context of Saudi Arabiaand the city ofArriyadh. Key issues identified related to the dry port development are long term planning and crosssector collaboration. The interconnection between the dry port and the overall transport system and aspects, such as location of business, city logistics, road and rail infrastructure, local, regional and national regulations, etc., is strong. This puts challenge on the coordination and alignment of the different organizations, their strategies and objectives. In a complex situation, such as developing a dry port with many stakeholders, it is crucial that the roles of all actors are clearly defined. This is essential for utilizing the dry port as a regional tool for planning. In that regard, it is appropriate that the site location decision is clearly connected with an overall city freight vision and strategy.展开更多
This paper develops a model for analyzing the potential of longer and heavier vehicles (LHVs) related to pre- and post-haulage in the intermodal rail-road transport chain (IRT). The paper considers the combined econom...This paper develops a model for analyzing the potential of longer and heavier vehicles (LHVs) related to pre- and post-haulage in the intermodal rail-road transport chain (IRT). The paper considers the combined economic and emission costs among three different transport networks including intermodal rail-road transport with current Swedish regulatory framework for trucks, intermodal rail-road transport with LHVs, and direct-road transport. The objective is to analyse the potential of high-capacity transport associated with pre- and post-haulage for enhancing the competitiveness of intermodal transport from a full-costs perspective. The model developed is applied to a Swedish context and case study. Research findings reveal that the break-even of the IRT compared to the direct road transport could be significantly lowered, which suggests the LHVs contribute to exploring the market of IRT over smaller flows.展开更多
Coordinated scheduling of multimode plays a pivotal role in the rapid gathering and dissipating of passengers in transport hubs. Based on the survey data, the whole-day reaching time distribution at transfer points of...Coordinated scheduling of multimode plays a pivotal role in the rapid gathering and dissipating of passengers in transport hubs. Based on the survey data, the whole-day reaching time distribution at transfer points of passengers from the dominant mode to the connecting mode was achieved. A GI/M K/1 bulk service queuing system was constituted by putting the passengers' reaching time distribution as the input and the connecting mode as the service institution. Through queuing theory, the relationship between average queuing length under steady-state and headway of the connecting mode was achieved. By putting the minimum total cost of system as optimization objective, the headway as decision variable, a coordinated scheduling model of multimode in intermodal transit hubs was established. At last, a dynamic scheduling strategy was generated to cope with the unexpected changes of the dominant mode. The instance analysis indicates that this model can significantly reduce passengers' queuing time by approximately 17% with no apparently increase in departure frequency, which provides a useful solution for the coordinated scheduling of different transport modes in hubs.展开更多
Characteristics of optical switching in a twin-core fibre coupler are numerically analysed under short pulse input by using supermode theory. The dynamic nonlinear coupled superlnode equations are derived, The numeric...Characteristics of optical switching in a twin-core fibre coupler are numerically analysed under short pulse input by using supermode theory. The dynamic nonlinear coupled superlnode equations are derived, The numerical results show that the input pulse width determines the power transfer and the pulse temporal profile in the output ports. The optimal switching characteristics can be obtained by selecting an appropriate initial pulse width. In addition, the switching characteristic curves are insensitive to the input pulse shape for either fundamental soliton pulse or Gaussian pulse input, but sensitive to pulse sharpness. A reduced switching power and a sharper switching transition can be obtained by using the sharp super-Gaussian pulse.展开更多
Overcoming the global sustainability challenges of logistics requires applying solutions that minimize the negative effects of logistics activities.The most efficient way of doing so is through intermodal transportati...Overcoming the global sustainability challenges of logistics requires applying solutions that minimize the negative effects of logistics activities.The most efficient way of doing so is through intermodal transportation(IT).Current IT systems rely mostly on road,rail,and sea transport,not inland waterway transport.Developing dry port(DP)terminals has been proven as a sustainable means of promoting and utilizing IT in the hinterland of seaport container terminals.Conventional DP systems consolidate container flows from/to seaports and integrate road and rail transportation modes in the hinterland which improves the sustainability of the whole logistics system.In this article,to extend literature on the sustainable development of different categories of IT terminals,especially DPs,and their varying roles,we examine the possibility of developing DP terminals within the framework of inland waterway container terminals(IWCTs).Establishing combined road–rail–inland waterway transport for observed container flows is expected to make the IT systems sustainable.As such,this article is the first to address the modelling of such DP systems.After mathematically formulating the problem of modelling DP systems,which entailed determining the number and location of DP terminals for IWCTs,their capacity,and their allocation of container flows,we solved the problem with a hybrid metaheuristic model based on the Bee Colony Optimisation(BCO)algorithmand themeasurement of alternatives and ranking according to compromise solution(i.e.,MARCOS)multi-criteria decision-making method.The results from our case study of the Danube region suggest that planning and developingDP terminals in the framework of IWCTs can indeed be sustainable,as well as contribute to the development of logistics networks,the regionalisation of river ports,and the geographic expansion of their hinterlands.Thus,the main contributions of this article are in proposing a novel DP concept variant,mathematically formulating the problems of its modelling,and developing an encompassing hybrid metaheuristic approach for treating the complex nature of the problem adequately.展开更多
A refractive index(RI)sensor based on elliptical core photonic crystal fiber(EC-PCF)has been proposed.The asymmetric elliptical core introduces the polarization-dependent characteristics of the fiber core modes.The pe...A refractive index(RI)sensor based on elliptical core photonic crystal fiber(EC-PCF)has been proposed.The asymmetric elliptical core introduces the polarization-dependent characteristics of the fiber core modes.The performances of intermodal interference between the intrinsic polarization fiber core modes are investigated by contrast in two interferometers based on the Mach-Zehnder(M-Z)and Sagnac interference model.In addition,the RI sensing characteristics of the two interferometers are studied by successively filling the three layers air holes closest to the elliptical core in the cladding.The results show that the M-Z interference between LP_(01)and LP_(11)mode in the same polarized direction is featured with the incremental RI sensing sensitivity as the decreasing interference length,and the infilled scope around the elliptical core has a weak correlation with the RI sensing sensitivity.Due to the high birefringence of LP11 mode,the Sagnac interferometer has better RI sensing performance,the maximum RI sensing sensitivity of 12000 nm/RIU is achieved under the innermost one layer air holes infilled with RI matching liquid of RI=1.39 at the pre-setting EC-PCF length of 12 cm,which is two orders of magnitude higher than the M-Z interferometer with the same fiber length.The series of theoretical optimized analysis would provide guidance for the applications in the field of biochemical sensing.展开更多
This paper presents a Web-based Decision Support System (Web-DSS) that was designed and developed to support and provide suggestions on the procedures taking place between a port and a dry port, which have to collabor...This paper presents a Web-based Decision Support System (Web-DSS) that was designed and developed to support and provide suggestions on the procedures taking place between a port and a dry port, which have to collaborate, work concurrently and optimize their joint operation. The system operates at the highest hierarchical level supervising a number of different components dealing with three different time scale horizons so as to provide assistance at operational, tactical and strategic level. The Web-based DSS coordinates and integrates the subsystems operating at lower levels and it interfaces with all the involved actors: customers, suppliers, relevant authorities so as to receive all the necessary information to come up with “optimal” suggestions and decisions. In this paper, the overall architecture is presented and the individual modules are described.展开更多
After the completion of Beijing New Airport, air-rail intermodality will become an important means of internal and external links in Jing-Jin-Ji Region. Jing-Jin-Ji Air-Rail Intermodality System is built and 7 sub-sys...After the completion of Beijing New Airport, air-rail intermodality will become an important means of internal and external links in Jing-Jin-Ji Region. Jing-Jin-Ji Air-Rail Intermodality System is built and 7 sub-systems are divided based on user demand analysis. Refer to the passenger process, the business process of the system is planned and the sub-systems are described using data flow diagram. The system provides theoretical support for the development of air-rail intermodal in Jing-Jin-Ji region.展开更多
Bangladesh has the lucrative maritime load centers or seaports to provide maritime logistics support as well as to do port transport business regionally with India, Nepal and Bhutan and internationally with China and ...Bangladesh has the lucrative maritime load centers or seaports to provide maritime logistics support as well as to do port transport business regionally with India, Nepal and Bhutan and internationally with China and Myanmar. Existing land ports as alternatives of dry ports are main strength of Bangladesh to connect with the seaports and offer port transport business for earning foreign exchange and able to play a vital role to develop the South Asia, SW part of China and Myanmar by serving the maritime logistics facilities timely and economically. In here, dry port concept is the main theme for developing port transport business where road, rail and waterways are the connectors or modes of transportation and seaports are the linking points with the sea world, Innovation is the key of success of a business idea and plan where maritime logistics business is the new opportunity of Bangladesh by using natural resources or seaport by mounting infrastructure facilities of nodes （seaport and dry port） and modes （road, rail and waterways） and adding speedy port transport for all. The intermodal freight transportation system is the new concept for creating the new era in the port transport business by using nodes, modes and technology innovatively. This research aims to find out the possible ways and innovations in maritime logistics for doing port transport business by using seaports and land ports by applying qualitative research methodology. The paper also describes the innovations of Rotterdam port as case study that facilitated the needs of a hinterland in Europe to explore the innovations for Bangladesh maritime logistics industry.展开更多
In this paper, four potential cities to host an intermodal terminal for containers flowing through the Togolese transport corridor are examined. The transport cost minimization through the corridor is the main objecti...In this paper, four potential cities to host an intermodal terminal for containers flowing through the Togolese transport corridor are examined. The transport cost minimization through the corridor is the main objective. Consequently, the transport modes that offer the least cost to the transport supply chain are proposed. To attain this goal the paper aims to identify the optimal location for an intermodal terminal on the Togolese corridor, by using the mathematical linear programming model. For this, three transport scenarios are analyzed, the rail, the road, and the combination of these two transport modes to each of the landlocked countries (LLCs) capital cities of Burkina Faso, Mali and Niger. Data of the average transport cost per mode, the cargo demand of the LLCs, and the distances from origin to destinations are input in the LINGO software. Based on the optimization results, we find that among the preselected terminals, the city of Mango located at 550 km in the northern part of the country is the optimal host location for an intermodal terminal along the Togolese corridor. The results of this study may be helpful to transport policy makers in the quest of rendering better servicing to the landlocked countries.展开更多
The objective of this paper is to create a process view of the development of intermodal transport solution from the basic idea to implementation. Special case of dedicated solutions based on large shippers’ volumes ...The objective of this paper is to create a process view of the development of intermodal transport solution from the basic idea to implementation. Special case of dedicated solutions based on large shippers’ volumes is chosen, where the shippers engage in the development process of the new solutions. Research is conducted using a qualitative approach: multiple case studies. Empirical data has been obtained through in-depth semi-structured interviews with relevant respondents involved in the development projects. Shippers’ perspective on the development process is studied. Development process can be described through a generic four-stage process: Initiation, Planning, Implementation, and Further Development. Different actors and different resources are required at the different stages. The complex process of establishing new intermodal solutions has lacked attention in the intermodal research. Understanding and improving the development process of new intermodal solutions is considered to have an important effect on the viability of intermodal transport and can help to understand the barriers that prevent companies from switching to intermodal. Development process of new dedicated intermodal solutions is a gradual process of building up the transport solution in a continuous interaction between shippers and transport service providers. Research has focused on the shipper perspective on inter-modal transport, showing that switching to an intermodal transport is not simply a mode choice issue, but involves a transition process that takes time, demands resources, cooperation/coordination between multiple parties, may require changes in the supply chain beyond the transport link, involves multiple actors, and involves an industry that is itself in a process of change.展开更多
Since rail-road transport uses road and rail networks and requires the transshipment infrastructures at the terminals, its competitiveness depends not only on the costs but also on the location of these terminals. Thi...Since rail-road transport uses road and rail networks and requires the transshipment infrastructures at the terminals, its competitiveness depends not only on the costs but also on the location of these terminals. This paper focused on providing a methodology for determining the optimal locations for intermodal freight transportation terminals in consolidation network. The goal is to minimize total costs in order to increase the efficiency of the transportation system. This paper also has allowed us to have an overview of the methods and models that exist for solving the problem of intermodal and terminal locating.展开更多
Efficient and effective movement of goods is very critical in today’s competitive environment especially for developing countries suffering from crippling logistics costs which limit their competitive ability in the ...Efficient and effective movement of goods is very critical in today’s competitive environment especially for developing countries suffering from crippling logistics costs which limit their competitive ability in the global economy. Putting in place an optimal logistics network design offers great potential for logistics cost reduction and service quality improvement [1]. Therefore, this paper presents a model for effective integration of inland intermodal terminal into logistics network. The model simultaneously determines the number and location of inland terminals in network that minimize the total cost of freight flow to hinterland. The model uses Abidjan port in Cote d’Ivoire as the case study for solving numeric examples. The problem will be formulated in the case of a rail-road network where post-routing is done by road and rail link between terminal. We present a linear optimization model which is implemented using LINGO Mathematical Modeling Language.展开更多
In this paper, a study on four African ports was taken out that all have the ca-pability to become a hub port that can serve the central African region. The paper sort to determine which port was most suitable and por...In this paper, a study on four African ports was taken out that all have the ca-pability to become a hub port that can serve the central African region. The paper sort to determine which port was most suitable and port indexing was the method that was used to evaluate these ports. The ports evaluated were the port of Kribi, the port of Bata, the port of Libreville and the port of Pointe-Noire. There were other models that were also used which included linear regression and linear programming which all contributed to providing the final results of the port with the most suitable potential to serve as a hub port and meaningful results were obtained. The final results showed that the port of Pointe-Noire was the most suitable port to serve the central African region as a hub port.展开更多
Major problem considered in this study was the intermodal routing problem of regional freight transportation in West Africa ECOWAS (Economic Community Of West Africa States), which can be defined as the problem of det...Major problem considered in this study was the intermodal routing problem of regional freight transportation in West Africa ECOWAS (Economic Community Of West Africa States), which can be defined as the problem of determining the freight flow quantity, the transportation mode in each transit corridor while satisfying the freight demand at each West Africa transit country (Mali, Burkina Faso and Niger). The objective was to minimize in land transportation costs. In order to solve optimally and represent the problem, this research employed a linear programming model. The model was solved using Lingo Mathematic Application. The model results showed that port oriented freight logistics in west Africa ECOWAS region do not flow along optimal path and such incur longer time and higher logistics cost than is geographically necessary.展开更多
基金supported by the National Natural Science Foundation of China(NSFC)(No.61805124)Natural Science Foundation of Ningbo City,China(No.2018A610023)+1 种基金3315 Innovation Team in Ningbo City,Zhejiang Province,ChinaK.C.Wong Magna Fund in Ningbo University,China。
文摘We report on the investigation of intermode beating mode-locked(IBML)pulse generation in a simple all-fiber Tm^3+-doped double clad fiber laser(TDFL).This IBML TDFL is implemented by matching longitudinal-mode frequency between 793 nm laser and TDFL without extra mode locker.The central wavelength of 1983 nm,the fundamental pulse frequency of 9.6 MHz and the signal-to-noise ratio(SNR)of>50 dB are achieved in this IBML TDFL.With laser cavity optimization,the IBML TDFL can finally generate an average output power of 1.03 W with corresponding pulse energy of 107 nJ.These results can provide an easily accessible way to develop compact large-energy,highpower TDFLs.
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.
基金National Natural Science Foundation of ChinaNo.72174035+5 种基金The National Key Research and Development ProjectNo.2023YFB4302200111 Project of ChinaNo.B20082The Talent Planning in DalianNo.2022RG05。
文摘The evolution mechanism of railway transportation network nodes driven by sea-rail intermodal transport(SRIT),a globally prevalent logistics method,has not been thoroughly investigated.From the perspective of SRIT,this study constructed a framework for understanding the evolution of railway container transport network nodes using Northeast China from 2013 to 2020 as a case study.It leverages proprietary data from 95306 Railway Freight E-commerce Platform.By employing the hybrid EWM-GA-TOPSIS model,complex network analysis,modified gravity model,and correlation and regression analyses,this study delves into the spatiotemporal patterns and dynamic transformations of railway container freight stations(RCFS).Finally,the long-term relationship between the RCFS and SRIT is explored.The results indicate that the spatial and temporal analysis of the RCFS in Northeast China from 2013 to 2020 revealed a clear polarisation trend,with the top-ranked stations mainly concentrated near ports and important transportation hubs.Additionally,the RCFS exhibited an expansionary trend;however,its development was uneven,and there was a significant increase in the number of new stations compared to abandoned stations,indicating an overall positive growth tendency.Moreover,the intensity of the SRIT at the RCFS in Northeast China notably increased.A significant positive linear relationship exists between SRIT and the freight capacity of all stations.A relatively pronounced correlation was observed for high-intensity stations,whereas a relatively weak correlation was observed for low-intensity stations.This study not only provides an effective framework for future research on RCFS within the context of SRIT but also serves as a scientific reference for promoting the implementation of the national strategy for multimodal transportation.
文摘The lack of adequate and modern transport infrastructures makes the cost of transport in Africa higher than the rest of the world. Most of the transport infrastructures that exist were constructed during the colonial era which makes inter-regional connectivity difficult. The African Union in collaboration with other organization has committed to bridge the transport gap in Africa but still, face some challenges. This paper discusses the main issues that contribute for the weak nature of transportation in Sub-Saharan Africa with regards to the main transport modes and seeks to establish the possibility of sustainable intermodal transport through the integration of the different transport modes. Some policy reforms and other bilateral agreements such as deregulating the transport markets in West and Central Africa have been suggested to facilitate the development of an effective and efficient transport network in the Sub-Saharan African region.
文摘The purpose of this paper is to explore the development process of a large scale dry port and to analyse what measures and actions are needed in order to support the decision making process and ensure an effective and efficient dry port that serves the City and the region’s current and future needs. The purpose is explored in the context of Saudi Arabiaand the city ofArriyadh. Key issues identified related to the dry port development are long term planning and crosssector collaboration. The interconnection between the dry port and the overall transport system and aspects, such as location of business, city logistics, road and rail infrastructure, local, regional and national regulations, etc., is strong. This puts challenge on the coordination and alignment of the different organizations, their strategies and objectives. In a complex situation, such as developing a dry port with many stakeholders, it is crucial that the roles of all actors are clearly defined. This is essential for utilizing the dry port as a regional tool for planning. In that regard, it is appropriate that the site location decision is clearly connected with an overall city freight vision and strategy.
文摘This paper develops a model for analyzing the potential of longer and heavier vehicles (LHVs) related to pre- and post-haulage in the intermodal rail-road transport chain (IRT). The paper considers the combined economic and emission costs among three different transport networks including intermodal rail-road transport with current Swedish regulatory framework for trucks, intermodal rail-road transport with LHVs, and direct-road transport. The objective is to analyse the potential of high-capacity transport associated with pre- and post-haulage for enhancing the competitiveness of intermodal transport from a full-costs perspective. The model developed is applied to a Swedish context and case study. Research findings reveal that the break-even of the IRT compared to the direct road transport could be significantly lowered, which suggests the LHVs contribute to exploring the market of IRT over smaller flows.
基金Projects(51278221,51378076)supported by the National Natural Science Foundation of China
文摘Coordinated scheduling of multimode plays a pivotal role in the rapid gathering and dissipating of passengers in transport hubs. Based on the survey data, the whole-day reaching time distribution at transfer points of passengers from the dominant mode to the connecting mode was achieved. A GI/M K/1 bulk service queuing system was constituted by putting the passengers' reaching time distribution as the input and the connecting mode as the service institution. Through queuing theory, the relationship between average queuing length under steady-state and headway of the connecting mode was achieved. By putting the minimum total cost of system as optimization objective, the headway as decision variable, a coordinated scheduling model of multimode in intermodal transit hubs was established. At last, a dynamic scheduling strategy was generated to cope with the unexpected changes of the dominant mode. The instance analysis indicates that this model can significantly reduce passengers' queuing time by approximately 17% with no apparently increase in departure frequency, which provides a useful solution for the coordinated scheduling of different transport modes in hubs.
基金Supported by the Natural Science Foundation of Guangdong Province （04010397）, and the Excellent Teacher Foundation of Guangdong Province （Q02084）.
文摘Characteristics of optical switching in a twin-core fibre coupler are numerically analysed under short pulse input by using supermode theory. The dynamic nonlinear coupled superlnode equations are derived, The numerical results show that the input pulse width determines the power transfer and the pulse temporal profile in the output ports. The optimal switching characteristics can be obtained by selecting an appropriate initial pulse width. In addition, the switching characteristic curves are insensitive to the input pulse shape for either fundamental soliton pulse or Gaussian pulse input, but sensitive to pulse sharpness. A reduced switching power and a sharper switching transition can be obtained by using the sharp super-Gaussian pulse.
文摘Overcoming the global sustainability challenges of logistics requires applying solutions that minimize the negative effects of logistics activities.The most efficient way of doing so is through intermodal transportation(IT).Current IT systems rely mostly on road,rail,and sea transport,not inland waterway transport.Developing dry port(DP)terminals has been proven as a sustainable means of promoting and utilizing IT in the hinterland of seaport container terminals.Conventional DP systems consolidate container flows from/to seaports and integrate road and rail transportation modes in the hinterland which improves the sustainability of the whole logistics system.In this article,to extend literature on the sustainable development of different categories of IT terminals,especially DPs,and their varying roles,we examine the possibility of developing DP terminals within the framework of inland waterway container terminals(IWCTs).Establishing combined road–rail–inland waterway transport for observed container flows is expected to make the IT systems sustainable.As such,this article is the first to address the modelling of such DP systems.After mathematically formulating the problem of modelling DP systems,which entailed determining the number and location of DP terminals for IWCTs,their capacity,and their allocation of container flows,we solved the problem with a hybrid metaheuristic model based on the Bee Colony Optimisation(BCO)algorithmand themeasurement of alternatives and ranking according to compromise solution(i.e.,MARCOS)multi-criteria decision-making method.The results from our case study of the Danube region suggest that planning and developingDP terminals in the framework of IWCTs can indeed be sustainable,as well as contribute to the development of logistics networks,the regionalisation of river ports,and the geographic expansion of their hinterlands.Thus,the main contributions of this article are in proposing a novel DP concept variant,mathematically formulating the problems of its modelling,and developing an encompassing hybrid metaheuristic approach for treating the complex nature of the problem adequately.
基金jointly supported by the Tianjin Natural Science Foundation(No.18JCQNJC71300)the National Natural Science Foundation of China(Nos.11804250,11904262 and 11704283)+1 种基金the Tianjin Education Commission Scientific Research Project(No.2018KJ146)the Opening Foundation of Tianjin Key Laboratory of Optoelectronic Detection Technology and Systems(No.2019LODTS004)。
文摘A refractive index(RI)sensor based on elliptical core photonic crystal fiber(EC-PCF)has been proposed.The asymmetric elliptical core introduces the polarization-dependent characteristics of the fiber core modes.The performances of intermodal interference between the intrinsic polarization fiber core modes are investigated by contrast in two interferometers based on the Mach-Zehnder(M-Z)and Sagnac interference model.In addition,the RI sensing characteristics of the two interferometers are studied by successively filling the three layers air holes closest to the elliptical core in the cladding.The results show that the M-Z interference between LP_(01)and LP_(11)mode in the same polarized direction is featured with the incremental RI sensing sensitivity as the decreasing interference length,and the infilled scope around the elliptical core has a weak correlation with the RI sensing sensitivity.Due to the high birefringence of LP11 mode,the Sagnac interferometer has better RI sensing performance,the maximum RI sensing sensitivity of 12000 nm/RIU is achieved under the innermost one layer air holes infilled with RI matching liquid of RI=1.39 at the pre-setting EC-PCF length of 12 cm,which is two orders of magnitude higher than the M-Z interferometer with the same fiber length.The series of theoretical optimized analysis would provide guidance for the applications in the field of biochemical sensing.
文摘This paper presents a Web-based Decision Support System (Web-DSS) that was designed and developed to support and provide suggestions on the procedures taking place between a port and a dry port, which have to collaborate, work concurrently and optimize their joint operation. The system operates at the highest hierarchical level supervising a number of different components dealing with three different time scale horizons so as to provide assistance at operational, tactical and strategic level. The Web-based DSS coordinates and integrates the subsystems operating at lower levels and it interfaces with all the involved actors: customers, suppliers, relevant authorities so as to receive all the necessary information to come up with “optimal” suggestions and decisions. In this paper, the overall architecture is presented and the individual modules are described.
文摘After the completion of Beijing New Airport, air-rail intermodality will become an important means of internal and external links in Jing-Jin-Ji Region. Jing-Jin-Ji Air-Rail Intermodality System is built and 7 sub-systems are divided based on user demand analysis. Refer to the passenger process, the business process of the system is planned and the sub-systems are described using data flow diagram. The system provides theoretical support for the development of air-rail intermodal in Jing-Jin-Ji region.
文摘Bangladesh has the lucrative maritime load centers or seaports to provide maritime logistics support as well as to do port transport business regionally with India, Nepal and Bhutan and internationally with China and Myanmar. Existing land ports as alternatives of dry ports are main strength of Bangladesh to connect with the seaports and offer port transport business for earning foreign exchange and able to play a vital role to develop the South Asia, SW part of China and Myanmar by serving the maritime logistics facilities timely and economically. In here, dry port concept is the main theme for developing port transport business where road, rail and waterways are the connectors or modes of transportation and seaports are the linking points with the sea world, Innovation is the key of success of a business idea and plan where maritime logistics business is the new opportunity of Bangladesh by using natural resources or seaport by mounting infrastructure facilities of nodes （seaport and dry port） and modes （road, rail and waterways） and adding speedy port transport for all. The intermodal freight transportation system is the new concept for creating the new era in the port transport business by using nodes, modes and technology innovatively. This research aims to find out the possible ways and innovations in maritime logistics for doing port transport business by using seaports and land ports by applying qualitative research methodology. The paper also describes the innovations of Rotterdam port as case study that facilitated the needs of a hinterland in Europe to explore the innovations for Bangladesh maritime logistics industry.
文摘In this paper, four potential cities to host an intermodal terminal for containers flowing through the Togolese transport corridor are examined. The transport cost minimization through the corridor is the main objective. Consequently, the transport modes that offer the least cost to the transport supply chain are proposed. To attain this goal the paper aims to identify the optimal location for an intermodal terminal on the Togolese corridor, by using the mathematical linear programming model. For this, three transport scenarios are analyzed, the rail, the road, and the combination of these two transport modes to each of the landlocked countries (LLCs) capital cities of Burkina Faso, Mali and Niger. Data of the average transport cost per mode, the cargo demand of the LLCs, and the distances from origin to destinations are input in the LINGO software. Based on the optimization results, we find that among the preselected terminals, the city of Mango located at 550 km in the northern part of the country is the optimal host location for an intermodal terminal along the Togolese corridor. The results of this study may be helpful to transport policy makers in the quest of rendering better servicing to the landlocked countries.
文摘The objective of this paper is to create a process view of the development of intermodal transport solution from the basic idea to implementation. Special case of dedicated solutions based on large shippers’ volumes is chosen, where the shippers engage in the development process of the new solutions. Research is conducted using a qualitative approach: multiple case studies. Empirical data has been obtained through in-depth semi-structured interviews with relevant respondents involved in the development projects. Shippers’ perspective on the development process is studied. Development process can be described through a generic four-stage process: Initiation, Planning, Implementation, and Further Development. Different actors and different resources are required at the different stages. The complex process of establishing new intermodal solutions has lacked attention in the intermodal research. Understanding and improving the development process of new intermodal solutions is considered to have an important effect on the viability of intermodal transport and can help to understand the barriers that prevent companies from switching to intermodal. Development process of new dedicated intermodal solutions is a gradual process of building up the transport solution in a continuous interaction between shippers and transport service providers. Research has focused on the shipper perspective on inter-modal transport, showing that switching to an intermodal transport is not simply a mode choice issue, but involves a transition process that takes time, demands resources, cooperation/coordination between multiple parties, may require changes in the supply chain beyond the transport link, involves multiple actors, and involves an industry that is itself in a process of change.
文摘Since rail-road transport uses road and rail networks and requires the transshipment infrastructures at the terminals, its competitiveness depends not only on the costs but also on the location of these terminals. This paper focused on providing a methodology for determining the optimal locations for intermodal freight transportation terminals in consolidation network. The goal is to minimize total costs in order to increase the efficiency of the transportation system. This paper also has allowed us to have an overview of the methods and models that exist for solving the problem of intermodal and terminal locating.
文摘Efficient and effective movement of goods is very critical in today’s competitive environment especially for developing countries suffering from crippling logistics costs which limit their competitive ability in the global economy. Putting in place an optimal logistics network design offers great potential for logistics cost reduction and service quality improvement [1]. Therefore, this paper presents a model for effective integration of inland intermodal terminal into logistics network. The model simultaneously determines the number and location of inland terminals in network that minimize the total cost of freight flow to hinterland. The model uses Abidjan port in Cote d’Ivoire as the case study for solving numeric examples. The problem will be formulated in the case of a rail-road network where post-routing is done by road and rail link between terminal. We present a linear optimization model which is implemented using LINGO Mathematical Modeling Language.
文摘In this paper, a study on four African ports was taken out that all have the ca-pability to become a hub port that can serve the central African region. The paper sort to determine which port was most suitable and port indexing was the method that was used to evaluate these ports. The ports evaluated were the port of Kribi, the port of Bata, the port of Libreville and the port of Pointe-Noire. There were other models that were also used which included linear regression and linear programming which all contributed to providing the final results of the port with the most suitable potential to serve as a hub port and meaningful results were obtained. The final results showed that the port of Pointe-Noire was the most suitable port to serve the central African region as a hub port.
文摘Major problem considered in this study was the intermodal routing problem of regional freight transportation in West Africa ECOWAS (Economic Community Of West Africa States), which can be defined as the problem of determining the freight flow quantity, the transportation mode in each transit corridor while satisfying the freight demand at each West Africa transit country (Mali, Burkina Faso and Niger). The objective was to minimize in land transportation costs. In order to solve optimally and represent the problem, this research employed a linear programming model. The model was solved using Lingo Mathematic Application. The model results showed that port oriented freight logistics in west Africa ECOWAS region do not flow along optimal path and such incur longer time and higher logistics cost than is geographically necessary.
