IPS - ESCE – DML
Permanent URI for this community
Browse
Browsing IPS - ESCE – DML by Author "Ayala Botto, Miguel"
Now showing 1 - 10 of 20
Results Per Page
Sort Options
- A closed-loop control scheme for a class of piecewise affine systemsPublication . Nabais, João; Pina, Luís; Silva, Miguel; Ayala Botto, Miguel
- A Constrained MPC Heuristic to Achieve a Desired Transport Modal Split at Intermodal HubsPublication . Nabais, João; Negenborn, R. R.; Carmona Benítez, R. B.; Ayala Botto, MiguelIntermodal hubs are a component of freight transportation networks that have as main goal to deliver cargo at the agreed time and at the agreed location. Currently, authorities are forcing transport operators to act in more sustainable ways. For intermodal hubs this is translated into making a preferable choice for sustainable transport modalities. In some cases, this is no longer a choice and is imposed on the intermodal hub in terms of a desired transport modal split. In this paper, a heuristic based on Model Predictive Control (MPC) to achieve a desired transport modal split at intermodal hubs is proposed. A terminal state constraint is used for the quantity of cargo assigned per modality over the prediction horizon to guide the cargo assignment. Feasibility of the optimization problem and cargo delivery at the agreed time are assured by relaxing the terminal state constraint. The proposed heuristic can anticipate the transport of cargo due to the inclusion of predictions, leading to a push of cargo towards the final destination. As cargo is moving in anticipation to the due time the transport is more robust to unforseen events, such as jams and weather conditions. The proposed heuristic is a step towards sustainable and synchromodal transportation networks. Simulation experiments illustrate the validity of these statements.
- Cooperative Relations Among Intermodal hubs and Transport Providers at Freight Networks Using an MPC ApproachPublication . Nabais, João; Negenborn, R. R.; Carmona Benítez, R. B.; Ayala Botto, MiguelFreight networks are more exposed to unforeseen events leading to delays compromising the delivery of cargo on time. Cooperation among different parties present at freight networks are required to accommodate the occurrence of delays. Cargo assignment to the available transport capacity at the terminal is addressed using a Model Predictive approach in this paper, taking into consideration the final destination and the remaining time until due time of cargo. A cooperative framework for transport providers and intermodal hubs is proposed in this paper. The cooperation is based on information exchange regarding the amount of cargo at risk of not reaching the destination on time. The terminal searches for a faster connection at the terminal to allocate the cargo at risk such that the final destination is reached on time. The proposed heuristic is a step towards sustainable and synchromodal transportation networks. Simulation experiments illustrate the validity of these statements.
- Data based modeling of a large scale water delivery systemPublication . Fernandes, Marta; Oliveira, Paulo; Vieira, Susana; Mendonça, Luís F.; Nabais, João; Ayala Botto, Miguel
- Efficient Operations at Intermodal Terminals Using a Multi-agent SystemPublication . Hipólito, Tomás; Nabais, João; Ayala Botto, Miguel
- Flexible discrete time state space model for canal pools.Publication . Nabais, João; Ayala Botto, MiguelWater is a vital resource for mankind used in activities such as agriculture, industry and domestic activity. Irrigation is one of the most consuming water resources in human activity. Irrigation canals are characterized for being spatially distributed crossing different administrative regions. As water is becoming a scarce and valuable resource, efficient engineering water conveyance networks are required. In this paper a discrete state space for modeling openchannels is presented. The well known Saint-Venant equations are first linearized for a steady state and then discretized using the Preissmann scheme. The resulting model is shown to be computational simple and flexible to accommodate different type of boundary conditions, in flow, water depth or hydraulic structures dynamics, which are important features for modeling complex water conveyance systems. The hydraulic model also offers monitoring ability along the canal axis and can therefore be integrated in fault diagnosis and tolerant control strategies. The model is validated with experimental data from a real canal property of the Evora University.
- Flexible framework for modeling water conveyance networksPublication . Nabais, João; Duarte, José; Ayala Botto, Miguel; Rijo, ManuelA flexible framework for modeling different water conveyance networks is presented. The network is modeled using a linear canal pool model based on the Saint-Venant equations to describe transportation phenomenon occurring in open channels. This model is used as a link to connect different nodes defined by gates or reservoirs. The linear pool model has interesting features namely the pool axis monitoring, the inflow along the pool axis and the ability to consider different boundary conditions. Based on these characteristics canal pool observers for leak detection and localization can be developed. It is shown that based on a finite difference scheme a good performance is obtained for low space resolution. The modeling framework is validated with experimental data from a real canal property of the Evora University. This is a challenging configuration due ´ to its strong canal pool coupling.
- Hierarchical Model Predictive Control for Optimizing Intermodal Container Terminal OperationsPublication . Nabais, João; Negenborn, R. R.; Ayala Botto, MiguelTransportation networks are large-scale complex spatially distributed systems whose purpose is to deliver commodities at the agreed time and at the agreed location. The network nodes (terminals, depots or warehouses) can be seen as the main decision making centers, as there the different economic actors interact with each other. In particular, the intermodal container terminal is responsible for storing containers until they are picked up for transport towards their final destination. Operations management at intermodal container terminals can be seen as a flow assignment problem. In this work we present a Hierarchical Model Predictive Control (HMPC) framework for addressing flow assignments in intermodal container terminals. The approach proposed is original due to its capability to keep track of the container class while solving a flow assignment problem respecting the available resources. However, the dimension of the problem to be solved grows with the number of container classes handled and the number of available connections at the terminal. A system decomposition inspired by container flows related to each connection served at the terminal is proposed to diminish the problem dimension to solve. The framework proposed is easily scalable to container terminals where hundreds of container classes and connections are available. The potential of the proposed framework is compared to a centralized Model Predictive Control (MPC) framework and is illustrated with a simulation study based on a long-term scheduled scenario
- Linear model for canal poolsPublication . Nabais, João; Ayala Botto, MiguelWater is vital for human life.Water is used widespread from agricultural to industrial as well as simple domestic activities. Mostly due to the increase on world population, water is becoming a sparse and valuable resource, pushing a high demand on the design of efficient engineering water distribution control systems. This paper presents a simple yet sufficiently rich and flexible solution to model open-channels. The hydraulic model is based on the Saint-Venant equations which are then linearized and transformed into a state space dynamic model. The resulting model is shown to be able to incorporate different boundary conditions like discharge, water depth or hydraulic structure dynamics, features that are commonly present on any water distribution system. Besides, due its computational simplicity and efficient monitoring capacity, the resulting hydraulic model is easily integrated into safety and fault tolerant control strategies. In this paper the hydraulic model is successfully validated using experimental data from a water canal setup.
- Model Predictive Control for a Sustainable Transport Modal Split at Intermodal Container HubsPublication . Nabais, João; Negenborn, R. R.; Ayala Botto, MiguelThe increase of international commerce and the expected container vessels capacity with 18, 000 TEU (twentyfoot equivalent unit) will put a considerable pressure on container hubs. High flow peaks will appear at gateway hubs in the transport network compromising the cargo transportation towards the hinterland and decreasing the network transport capacity. Moreover, authorities are forcing transport operators to operate in more sustainable ways. For container hubs this is translated into making a preferable choice for barge and train modalities before opting for truck modality. In this work we present a framework based on Model Predictive Control (MPC) to address the so-called transport modal split problem for the outgoing cargo at container hubs. We use two features (destination and due time) to categorize the cargo present at a container hub and develop a dynamic model to make predictions of cargo volume over time. The controller decision takes into account transporting cargo towards the final destination while opting for sustainable transport modalities. The approach is able to assign cargo in advance to the existing connections at the hub in order to overcome predicted cargo peaks in the future. The framework can also be used to choose between different connection schedules. Giving decision freedom to container hubs is a step towards a synchromodal and more flexible transport network. These statements are illustrated with two simulation examples.