Voyage Time Research Articles

Path Planning for Autonomous Underwater Vehicles With Simultaneous Arrival in Ocean Environment

This article focuses on the time-minimum path planning problem of autonomous underwater vehicles (AUVs) with the constraint of simultaneous arrival in an ocean environment. The overall framework can be divided into two successive modules, and both of them are solved by the biased min-consensus (BMC) method, which introduces the edge weight into the standard min-consensus protocol. The first module plans each AUV's path under the BMC protocol, respectively, along which the AUV will avoid obstacles and navigate to the destination with the minimum time through the ocean current. Incorporating the cooperative constraint of simultaneous arrival, the second part chooses the AUV path with the maximal voyage time as a benchmark, and replans other AUVs’ paths using the BMC method until their corresponding voyage time is approximately equal to the benchmark. The simulation results in various scenarios demonstrate the strong applicability and high effectiveness of our method.

Smart Car Sharing

With the tremendous increment in number of vehicles on street, individuals around the nation particularly in metro urban areas have begun confronting issue now because of increment in rush hour gridlock which added a hour or so to their day by day voyaging time. Out of couple of, one of the techniques to decrease this hopelessness of explorers is to make them share vehicles. In Existing System, With in the city or Particular Destination just The Car Services is Available. The objective of this work is to design a “car pooling,” which is a use of vehicle sharing (additionally called lift-sharing or ride-sharing) in which drivers (alone-riders) who are heading out to work alone can request individual travelers through our application. For the individuals who utilize open transport framework to go to work day by day can utilize this application to discover drivers who are heading out to a similar goal and willing to share ride. Get-together individuals into normal excursions prompts individual and social productivity. At an individual dimension, it lessens the complete voyaging cost and the driving worry also. In spite of the fact that it is less agreeable than utilizing the individual vehicle and individuals generally require more opportunity for playing out the movement, the wide acknowledgment of the mutual use portability demonstrates its feasibility, with down to earth advancements not so much investigated. By utilizing this strategy the Users can Travel Anywhere with Low expense. This won’t just dispose of the additional voyage time of travelers yet will likewise help condition by diminishing contamination and traffic on streets. This person to person communication application is additionally called toll sharing and time sharing as you will be you are imparting both to individual voyagers.

A route optimization method based on simulated annealing algorithm for wind-assisted ships

Aimed to the global demand for energy-saving and emission-reduction, and urgent need of shipping industry to cut down fuel costs, the wind-assisted ships are taken as an effective way for energy-saving and emission reduction of transoceanic crossing ships, this work focused on route optimization model to provide theoretical basis and technical support for wind-assisted ships. Firstly, this work analyses the route optimization of the wind-assisted ship, and two optimization objectives are defined. Secondly, the route optimization models for the minimum fuel consumption under the limited voyage time and the minimum voyage time on the condition of fixed main engine power were built separately, and the optimization algorithm based on simulated annealing was designed. At last, a 76,000DWT wind-assisted ship was taken as the experimental ship, and the feasibility and rationality of the model and algorithm was verified. As the simulation shown, the optimal route solved in this paper is effective in path planning problem of wind-assisted ship and has practical significance.

Tracking boil off gas generation into liquefied natural gas supply chain using HYSYS simulator

Liquefied natural gas (LNG) is becoming one of the prominent clean energy sources with its abundance, high potential energy, and low emission and price. Unavoidable reality is that boil off gas (BOG) generates, because of low temperature of LNG, about -162.5 °C at 101.3 kPa for storage and transportation of liquefied natural gas. As natural gas productions increasing globally, BOG and handling problems become serious critical subject in both economic and environment regulations. In this work, liquefied natural gas storage facilities and loading facilities are simulated to investigate the generated BOG by calculating the heat leaks through cargo tank, pipelines, storage tank, and the generated heat by equipment’s. Later, boil off gas rates are estimated for each sector into LNG supply chain with different operational conditions, parameters and voyage time. Factors that affect BOG such as operation temperatures and pressures, methane content, and nitrogen content are presented. Current study would help to properly store and transport LNG to minimize the venting of BOG into supply chain, and thus reducing greenhouse emissions, save energy, and reducing waste of natural gas.

Optimal ice routing of a ship with icebreaker assistance

Offshore development and growing prospects of commercial shipping in the Arctic pose the challenge of optimal ship routing in ice. Route selection in spatially distributed ice conditions significantly affects the voyage time and determines the efficiency of shipping. Most of the applied methods of ice routing solve the problem of a single vessel route selection without considering icebreaker support. At the same time, the real practice of ice navigation is closely connected with icebreaker assistance. It allows reducing the voyage time and fuel consumption, while having additional costs for icebreaker services. Such opposite trends set an optimization task that has not been studied in detail before. In this article, we presented the formulation of a Single Vessel and Icebreaker Assisted Ice Routing optimization problem in non-stationary ice conditions. We considered the icebreaker assistance as an integral part of the overall route optimization problem, and used the economic criterion to optimize both ship route and amount of icebreaker involvement. The article contains the adapted mathematical formulations of classical graph-based and wave-based routing problems in order to consider icebreaker assistance. To prove the practical applicability of these formulations, we developed special subject-oriented research software and implemented there both graph-based (Dijkstra, A*) and the wave-based ice routing methods. Using this developments, we conducted several case studies and made the analysis of strengthens and weaknesses of the alternative routing methods in case of ice operation. The results of the study may serve an additional step to the practical implementation of ice routing technologies and planning of icebreaker resources.

Ensuring the given level of the voyage efficiency considering the risks factors associated with the charter party terms

The terms of the agreement for voyage chartering of the vessel (voyage charter-party) are identified as those the wordings of which can affect the risk of increasing the voyage time and, accordingly, the voyage costs of the shipowner-carrier. Their possible wordings are given, the nature of their impact on the components of the voyage time are characterized. Noted the possibility of their assessment by shipowner during the negotiations before the charter-party conclusion. The approach of the ensuring the voyage efficiency is developed. It based on the assessment the risk of the voyage time increasing due to the charter-party terms

Joint Ship Schedule Design and Sailing Speed Optimization for a Single Inland Shipping Service with Uncertain Dam Transit Time

Inland shipping has received extensive attention in practice and is a high energy-consuming service sensitive to the river streamflow speed and the uncertain lock traversing time of dams. In this study, we propose a joint ship schedule design and sailing speed optimization problem for a single inland shipping service by incorporating the effects of nonidentical streamflow speed and the uncertain dam transit time. A bi-objective programming model is developed for the proposed problem to simultaneously minimize the total bunker consumption and the ship round-trip time with service level constraints. The service level at each port call is captured by the punctual arrival probability of the ship not less than a predefined value. By introducing the term of buffer times, we analytically derive the Pareto optimal solutions of the ship sailing speeds and schedule. The theoretical method is extended to the case with an arbitrary number of dams and the uncertain port service and leg voyage time. We also examine the relationship between the Pareto optimal solution in this study and the solutions of the previous joint sailing speed and schedule optimization problems in the liner shipping service design. Numerical experiments based on the Yangtze River are conducted. The online appendix is available at https://doi.org/10.1287/trsc.2017.0808 .

A sensor-dependent vibration data driven fault identification method via autonomous variational mode decomposition for transmission system of shipborne antenna

With the increasing distance and time of voyage, condition monitoring and fault diagnosis of shipborne antenna play a crucial role in ship communication for navigation safety. However, it is still a challenging task to identify the hidden shipborne antenna fault from practical sensor-dependent vibration signals since the vibration features are always multi-modulated and submersed by heavy noise. Therefore, autonomous variational mode decomposition (AVMD) based on Independence-oriented Variational Mode Decomposition (IOVMD) and the Largest Lyapunov Exponent (LLE) criterion is proposed in this paper. First, the signal is decomposed into Intrinsic Mode Functions (IMFs) by IOVMD. Second, LLE of modes is calculated to measure fault information degree and then modes without fault features are eliminated. The combination rule is also defined and modes are combined orderly to enhance the fault feature expression. Then, an index structured by Kurtosis and LLE of combined signals is calculated and the combined signal is selected for demodulation. Finally, the combined signal is analyzed for fault identification by Hilbert Demodulation. A simulation and two cases show the effectiveness and superiority of the proposed method.

Effects of Anomalous Cosmic Rays on the Structure of the Outer Heliosphere

Abstract Based on Voyager 1 observations, some anomalous cosmic rays (ACRs) may have crossed the heliopause and escaped into the interstellar medium, providing a mechanism of energy transfer between the inner and outer heliosheaths that is not included in conventional magnetohydrodynamics (MHD) models. In this paper, we study the effect of energetic particles’ escape through the heliopause on the size and shape of the heliosphere using a simple model that includes diffusive transport of cosmic rays. We show that the presence of ACRs significantly changes the heliosphere structure, including the location of the heliopause and termination shock. It was found that the heliopause would contract for certain values of the ACR diffusion coefficients when the diffusive particles’ pressure is comparable to the pressure of the plasma background. The difference in Voyager 1 and 2 observations of energetic particles during their respective termination shock crossings is interpreted here as due to the differences in diffusion environments during the different phases of the solar cycle. The shorter period of enhanced ACR intensities upstream of the shock measured by Voyager 2 may have been caused by weaker radial diffusive transport compared with the time of Voyager 1 crossing. We conclude that ACR diffusive effects could be prominent and should be included in MHD models of the heliosphere.

A Study of Ballast Water Treatment Using Engine Waste Heat

Heat treatment of ballast water using engine waste heat can be an advantageous option complementing any proven technology. A treatment system was envisaged based on the ballast system of an existing, operational crude carrier. It was found that the available waste heat could raise the temperatures by 25 °C and voyage time requirements were found to be considerable between 7 and 12 days to heat the high volumes of ballast water. Further, a heat recovery of 14–33% of input energies from exhaust gases was recorded while using a test rig arrangement representing a shipboard arrangement. With laboratory level tests at temperature ranges of around 55–75 °C, almost complete species mortalities for representative phytoplankton, zooplankton and bacteria were observed while the time for exposure varied from 15 to 60 s. Based on the heat availability analyses for harvesting heat from the engine exhaust gases(vessel and test rig), heat exchanger designs were developed and optimized using Lagrangian method applying Bell–Delaware approaches. Heat exchanger designs were developed to suit test rig engines also. Based on these designs, heat exchanger and other equipment were procured and erected. The species’ mortalities were tested in this mini-scale arrangement resembling the shipboard arrangement. The mortalities realized were > 95% with heat from jacket fresh water and exhaust gases alone. The viability of the system was thus validated.

Predicting local ice loads on ship bow as a function of ice and operational conditions in the Southern Sea

ABSTRACTTransportation in ice-prone waters is a timely topic because of the pursuit of natural resources and sea routes. S.A. Agulhas II voyaged in Antarctic waters during the austral summer of 2013–14. This paper studies how the local ice-induced loads on the ship bow are affected by different ice and operational conditions. A hierarchical Gaussian process model was used to study how the load distribution parameters change in different conditions. The operational conditions are described by ship speed, whereas the ice conditions varied from thin, first-year ice, to thick, multiyear ice. Because of this variation, the ice conditions are not represented by ice thickness alone but also by latitude, temperature and voyage time which represent the unmeasured ice strength. The predicted loads from the model match well with the measured loads. According to the model, loads increase in higher ship speed and ice thickness combination, further south, later in the summer and in higher temperatures.

Analysis of Battery/Generator Hybrid Container Ship for CO2 Reduction

Ships entering designated emission control areas are required to reduce emission gases drastically, in accordance with international maritime organization regulations or local policies. In this regard, a hybrid power system, which is a combination of conventional generators and lithium-ion batteries as a type of energy storage system (ESS), has been applied to ships. However, this hybrid concept has been focused on small-sized coastal ships, because they have a short voyage time or require high peak power for a short time. And by extension, this paper demonstrates the potential of a hybrid power system for medium-sized oceangoing ships. First, a medium-sized container ship is selected as a target ship. The electric load profile near ports is defined to select the optimum capacity of the ESS and generators. Then, to verify the advantage of the proposed system, this paper uses MATLAB/Simulink software for simulation. Finally, carbon dioxide (CO2) emissions are compared between the proposed power system and the conventional one which uses only generators. The results show that overall, 8.6% ~20.7% CO2 emissions can be reduced, depending on the electric load conditions of a ship. Hence, a hybrid power system can be an eco-friendly solution for medium-sized oceangoing ships, as well as small-sized coastal ships.

A Multiobjective Path-Planning Algorithm With Time Windows for Asset Routing in a Dynamic Weather-Impacted Environment

This paper presents a mixed-initiative tool for multiobjective planning and asset routing (TMPLAR) in dynamic and uncertain environments. TMPLAR is built upon multiobjective dynamic programming algorithms to route assets in a timely fashion, while considering fuel efficiency, voyage time, distance, and adherence to real world constraints (asset vehicle limits, navigator-specified deadlines, etc.). TMPLAR has the potential to be applied in a variety of contexts, including ship, helicopter, or unmanned aerial vehicle routing. The tool provides recommended schedules, consisting of waypoints, associated arrival and departure times, asset speed and bearing, that are optimized with respect to several objectives. The ship navigation is exacerbated by the need to address multiple conflicting objectives, spatial and temporal uncertainty associated with the weather, multiple constraints on asset operation, and the added capability of waiting at a waypoint with the intent to avoid bad weather, conduct opportunistic training drills, or both. The key algorithmic contribution is a multiobjective shortest path algorithm for networks with stochastic nonconvex edge costs and the following problem features: 1) time windows on nodes; 2) ability to choose vessel speed to next node subject to (minimum and/or maximum) speed constraints; 3) ability to select the power plant configuration at each node; and 4) ability to wait at a node. The algorithm is demonstrated on six real world routing scenarios by comparing its performance against an existing operational routing algorithm.

Investigation of the effect of ship size and marine transportation distance on the possible decrease of voyage efficiency

The object of this research is the voyage efficiency of ship in terms of its deviation under the influence of risk factors. Time charter equivalent is considered as an efficiency indicator. The aim of this research is to establish the effect of the main characteristics of the ship and the voyage to the possible deviation of the ship efficiency. During research the next methods are used: Regression analysis – to establish a kind of connection between the characteristics of the ship (voyage) and elements of the operating costs and income. Probability theory (characteristics and properties of the normal distribution law) – to assess possible deviations of voyage time. Functional analysis to investigate the effect of voyage and ship characteristics on possible decrease in the voyage efficiency. Principal types of dependencies of income and cost elements for ship (freight rate, fuel consumption, port charges) in voyage on cargo capacity and transportation distance. Obtained patterns allow to formulate expression of efficiency parameter deviation of the voyage ship as a function of voyage and ship characteristics. Conclusions about the effect of ship size and transportation distance on the possible deviations of voyage efficiency are made. In particular, it is found that possible reduction in the time charter equivalent with an increase in voyage duration is less significant than at shorter distances . Also, it is determined that a significant effect along with the standard deviation of voyage time has a level of freight rates – even its slight increase results in a notable difference in efficiency «losses». These results allow to estimate the possible deviations of voyage efficiency under the influence of risk factors. Value of time charter equivalent deviation can serve as an additional criterion for decision about ship charter, along with parameters of the daily incomes and time charter equivalent, being a kind of risk assessment of voyage efficiency reduction.

Application of improved isochron method in ship’s minimum voyage time weather routing

Application of improved isochron method in ship’s minimum voyage time weather routing

Cervantes, fray Juan Gil y los mercaderes valencianos

En el artículo se dan a conocer varios documentos inéditos referentes a Cervantes, Fray Juan Gil y a varios mercaderes amigos de ambos personajes. Están fechados principalmente en los años 1580-1592, época de los viajes redentores a Argel del padre Gil e inmediatos sucesores, fecha también de la liberación de Cervantes y de su posterior estancia en Valencia. Especial interés tienen los documentos relativos a los contratos de fletamento de las naves redentoras. Digno de destacar es la sorprendente intervención de Cervantes, ofreciendo información de primera mano sobre un cautivo de Argel. Los que recibieron esta información, unos mercaderes sin escrúpulos, urdieron unas fraudulentas apuestas, donde se jugaron altas cantidades de dinero, en las que se vieron implicados varios centenares de personas acaudaladas, como mercaderes y maestros artesanos. Se apostaba sobre la vida o muerte de un pescador del Grao al que se daba por muerto, víctima de unos supuestos criminales que se hallaban detenidos en las cárceles de Valencia.

Global MHD simulations of Neptune's magnetosphere

AbstractA global magnetohydrodynamic (MHD) simulation has been performed in order to investigate the outer boundaries of Neptune's magnetosphere at the time of Voyager 2's flyby in 1989 and to better understand the dynamics of magnetospheres formed by highly inclined planetary dipoles. Using the MHD code Gorgon, we have implemented a precessing dipole to mimic Neptune's tilted magnetic field and rotation axes. By using the solar wind parameters measured by Voyager 2, the simulation is verified by finding good agreement with Voyager 2 magnetometer observations. Overall, there is a large‐scale reconfiguration of magnetic topology and plasma distribution. During the “pole‐on” magnetospheric configuration, there only exists one tail current sheet, contained between a rarefied lobe region which extends outward from the dayside cusp, and a lobe region attached to the nightside cusp. It is found that the tail current always closes to the magnetopause current system, rather than closing in on itself, as suggested by other models. The bow shock position and shape is found to be dependent on Neptune's daily rotation, with maximum standoff being during the pole‐on case. Reconnection is found on the magnetopause but is highly modulated by the interplanetary magnetic field (IMF) and time of day, turning “off” and “on” when the magnetic shear between the IMF and planetary fields is large enough. The simulation shows that the most likely location for reconnection to occur during Voyager 2's flyby was far from the spacecraft trajectory, which may explain the relative lack of associated signatures in the observations.

Cooperative path planning for multi-AUV in time-varying ocean flows

For low-speed underwater vehicles, the ocean currents has a great influence on them, and the changes in ocean currents is complex and continuous, thus whose impact must be taken into consideration in the path planning. There are still lack of authoritative indicator and method for the cooperating path planning. The calculation of the voyage time is a difficult problem in the time-varying ocean, for the existing methods of the cooperating path planning, the computation time will increase exponentially as the autonomous underwater vehicle (AUV) counts increase, rendering them unfeasible. A collaborative path planning method is presehted for multi-AUV under the influence of time-varying ocean currents based on the dynamic programming algorithm. Each AUV cooperates with the one who has the longest estimated time of sailing, enabling the arrays of AUV to get their common goal in the shortest time with minimum time-difference. At the same time, they could avoid the obstacles along the way to the target. Simulation results show that the proposed method has a promising applicability.

A semi-empirical ship operational performance prediction model for voyage optimization towards energy efficient shipping

Voyage optimization is a practice to select the optimum route for the ship operators to increase energy efficiency and reduce Green House Gas emission in the shipping industry. An accurate prediction of ship operational performance is the prerequisite to achieve these targets. In this paper, a modified Kwon׳s method was developed to predict the added resistance caused by wave and wind for a specific ship type, and an easy-to-use semi-empirical ship operational performance prediction model is proposed. It can accurately predict the ship׳s operational performance for a specific commercial ship under different drafts, at varying speeds and in varying encounter angles, and then enables the user to investigate the relation between fuel consumption and the various sea states and directions that the ship may encounter during her voyage. Based on the results from the operational performance prediction model and real time climatological information, different options for the ship׳s navigation course can be evaluated according to a number of objectives, including: maximizing safety and minimizing fuel consumption and voyage time. By incorporating this into a decision support tool, the ship׳s crew are able to make an informed decision about what is the best course to navigate.In this study the Energy Efficiency of Operation (EEO) is defined as an indicator to illustrate the ratio of main engine fuel consumption per unit of transport work. Two case studies are carried out to perform the prediction of ship operational performance for Suezmax and Aframax Oil Tankers, and the results indicate that the semi-empirical ship operational performance prediction model provides extremely quick calculation with very reasonable accuracy, particularly considering the uncertainties related to the parameters of interest for the case study data. Within the case studies, the additional fuel consumption caused by the combined hull and propeller fouling and engine degradation is included in the model as a time-dependent correction factor. The factor may assist the ship owner/operator to determine the hull coating selection, and/or the dry-docking and main engine maintenance strategy.

The Role of Ferry and Ro-Ro Shipping in Sustainable Development of Transport

Abstract As far as sustainable transport development is concerned, transfer of cargo from road transport to short sea shipping, which, according to the common opinion, generates lower external costs, is one of the objectives of the European Union policy. However, the latest research results indicate that some Ro-Ro vessels and ferries generate higher external costs than road transport. In light of this, benefits resulting from transferring the cargo from road to sea seem to be questionable. The main aim of the article is answering the question whether, and if so, how ferry and Ro-Ro shipping contributes to development of sustainable transport? In order to answer this question, an analysis of ferry and Ro-Ro shipping lines functioning in European transport system has been conducted. The article presents research results based on an analysis of approx. 900 ferry and Ro-Ro shipping lines considering the length and time of voyage compared to alternative road transport. Usually, the course of sea shipping route does not cover the route of the road transport, and therefore the lengths of both routes frequently considerably differ, which significantly affects the total external costs generated by them. On the basis of the analysis, the shipping lines have been classified according to the criterion of their substitutability to road transport and their role in sustainable transport development.