Simulation of railroad terminal operations and traffic control strategies in critical scenarios

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An ETA Prediction Model for Intermodal Transport Networks Based on Machine Learning

Transparency in transport processes is becoming increasingly important for transport companies to improve internal processes and to be able to compete for customers. One important element to increase transparency is reliable, up-to-date and accurate arrival time prediction, commonly referred to as estimated time of arrival (ETA). ETAs are not easy to determine, especially for intermodal freight transports, in which freight is transported in an intermodal container, using multiple modes of transportation. This computational study describes the structure of an ETA prediction model for intermodal freight transport networks (IFTN), in which schedule-based and non-schedule-based transports are combined, based on machine learning (ML). For each leg of the intermodal freight transport, an individual ML prediction model is developed and trained using the corresponding historical transport data and external data. The research presented in this study shows that the ML approach produces reliable ETA predictions for intermodal freight transport. These predictions comprise processing times at logistics nodes such as inland terminals and transport times on road and rail. Consequently, the outcome of this research allows decision makers to proactively communicate disruption effects to actors along the intermodal transportation chain. These actors can then initiate measures to counteract potential critical delays at subsequent stages of transport. This approach leads to increased process efficiency for all actors in the realization of complex transport operations and thus has a positive effect on the resilience and profitability of IFTNs

Models and Methods for Multi-Actor Systems

2010/2011The study of the models and methods to apply to multi-actor systems is a widely discussed research topic in the related scientific literature. The multi-actor systems are defined as systems that are characterized by the presence of several autonomous elements, of different decision makers and of complex rules that allow the communication, the coordination and the connection of the components of such systems. Commonly, the study of Multi-Actor System, MAS, recalls the well-known issues concerning the multi-agent systems. The research topic related to the multi-agent system firstly started to appear in scientific literature in 1980s, mainly in relation to the computer science and artificial intelligence. In this dissertation, in particular, the study of the multi-agent systems, and specifically of the multi-actor systems, is taken into account merely in relation to the distinctive features of complexity that characterize such systems and not to the issues concerning the agent-oriented software engineering. Therefore, the research results presented in this thesis are focused on the development and on the realization of innovative models and methodologies to face the management and the decision making mechanisms applied to complex multi-actor systems. This dissertation especially focuses on two different examples of multi-actor systems in two very diverse perspectives. The former deals with the research problem related to intermodal transportation networks, while the latter with the so called consensus problem in distributed networks of agents. Concerning the research problem related to the intermodal logistic systems, the research activity addresses the management of their more and more increasing complexity by the applications of the modern Information and Communication Technologies (ICT) tools that are key solutions to achieve the efficiency and to enhance logistics competitiveness. The related scientific literature still seems lacking in addressing with adequate attention the impact of these new techniques on the management of these complex systems and, moreover, there is an apparent lack of a systematic and general methodology to describe in detail the multiplicity of elements that can influence the dynamics and the corresponding information and decision making structure of intermodal transportation systems. The innovative results presented in this dissertation are focused on the development of an Integrated System, IS, devoted to manage intermodal transportation networks at the tactical as well as operational decision level to be used by decision makers both in off-line planning and real time management. To specify the Integrated System, a reference model is developed relying on a top-down metamodeling procedure. These innovative research results are a contribution to bridge the gap and to propose not only a systematic modeling approach devoted to describe a generic multi-actor logistic system, but also a management technique based on a closed loop strategy. The second example of application is focused on a topic that is widely discussed in scientific literature related to the study of the multi-actor collective behaviors in a distributed network. The interaction protocols that allow the agents to reach the convergence to a common value is called consensus or agreement problem. This research problem is particularly studied in the context of cooperative control of multi-agent systems because the agents are autonomous, independent and have to interact in a distributed network. The presented research results address the investigation of new and fast alignment protocols that enhance the performances of the standard iteration protocols for particular topologies of digraphs on the basis of a triangular splitting of the standard iteration matrix. The examined examples, the models and the methodologies applied to analyze them, are very different in the two cases and this testifies the large extent of research problems related to the multi-actor systems.L’analisi di modelli e metodi da sviluppare e da applicare nel contesto dei sistemi multi-attoriali costituisce un tema molto variegato e discusso nella letteratura scientifica internazionale. I sistemi multi-attoriali sono sistemi che si contraddistinguono per la presenza di molti elementi autonomi diversi tra loro, di molteplici decisori e di complesse regole che determinano la comunicazione, il coordinamento e la connessione all'interno di tali sistemi. Frequentemente, facendo riferimento a sistemi multi-attoriali, Multi-Actor Systems, si richiama il tema molto attuale dei sistemi multi agente, Multi-Agent Systems. Diffusisi a partire dal 1980, i sistemi multi agente sono spesso studiati in relazione alle metodologie di sviluppo dell'ingegneria del software. Nel presente lavoro di tesi, il tema dei sistemi multi-agente, ed in particolare di quelli multi-attoriali, non viene analizzato in questo contesto, ma in relazione alle tecniche decisionali da adottare per gestire sistemi caratterizzati da un alto livello di complessità. In tale ambito, i risultati presentati all'interno di questa dissertazione sono focalizzati sullo sviluppo e sulla realizzazione di nuovi metodi e di nuove metodologie, in grado di affrontare la gestione della complessità dei sistemi multi-attoriali. Vengono in particolare esaminate due diverse problematiche, in due contesti completamente diversi e con tecniche differenti, a testimoniare le vaste applicazioni che riguardano i sistemi multi-attoriali. I problemi analizzati sono incentrati, in primo luogo, su un'applicazione inerente la gestione di sistemi logistici intermodali ed, in secondo luogo, sullo studio delle regole o protocolli di interazione in una rete distribuita di agenti autonomi. Per quanto riguarda l'aspetto legato ai sistemi intermodali di trasporto, un tema molto discusso nella letteratura scientifica recente, l'analisi si focalizza sulla gestione della loro sempre crescente complessità, tramite l'utilizzo di sistemi dell'Information and Communication Technology, ICT. Questi strumenti richiedono metodi e modelli che sono innovativi rispetto a quanto è presente nella letteratura scientifica, all'interno della quale è stata riscontrata la mancanza di un approccio sistematico e sufficientemente ad alto livello per la realizzazione di una metodologia in grado di descrivere allo stesso tempo sia la molteplicità di elementi che influenzano le dinamiche e le informazioni, sia le strutture decisionali dei sistemi intermodali. L'innovazione dei risultati presentati in questa tesi si focalizza proprio sull'esigenza di proporre un sistema integrato, Integrated System (IS), basato su un metamodello delle reti intermodali di trasporto, che fornisca un valido supporto ai decisori sia a livello tattico che operativo. Il secondo aspetto affrontato in questa tesi riguarda un altro argomento di largo ed attuale interesse nella letteratura scientifica, che viene comunemente chiamato problema del consenso. Questo problema affronta lo studio di come diversi agenti autonomi collocati su una rete distribuita siano in grado di comunicare e di accordarsi su un valore comune, senza la presenza di un decisore centrale. A questo scopo ci sono degli algoritmi che specificano le regole o protocolli di interazione tra i diversi agenti. In tale contesto, i risultati proposti si focalizzano su alcune problematiche rappresentate dal protocollo classico del consenso e soprattutto sulla sua scarsa efficienza in particolari conformazioni delle reti di agenti. Il lavoro di tesi propone, quindi, un approccio di suddivisione, splitting, della matrice standard di iterazione, di tipo triangolare, che presenta notevoli vantaggi in termini di performance rispetto all'algoritmo classico. Lo studio di problemi multi-attoriali, pertanto, richiede lo sviluppo di innovative metodologie decisionali e di nuovi metodi di gestione delle comunicazioni, per rispondere al livello sempre crescente di complessità, offrendo in questo modo alcuni spunti molto interessanti per la ricerca.XXIV Ciclo198

ОПТИМИЗАЦИЯ ПАРАМЕТРОВ РАБОТЫ ТРАНСПОРТНО-СКЛАДСКИХ КОМПЛЕКСОВ

When determining the operating parameters of transport and storage complexes, the necessity to choose an optimization criterion arises. A methodology for determining the optimal operating parameters of complexes, including methods of calculating the optimal amount of loading and unloading mechanisms and stations, is developed. Results of the research show that when calculating the optimal amount of loading and unloading mechanisms and stations it is advisable to take into account the ratio of arrival intervals of a rolling stock for loading and unloading, along with duration of the normative operating time for a single discharge mechanism. In order to determine the optimal number of loading and unloading mechanisms and stations in storage complexes, a criterion of minimum total expenditures of transport and storage enterprises for performing loading and unloading operations and transport organizations in relation with downtime of the rolling stock during loading and unloading operations is proposed. It is determined that economizing total expenditures of transport companies and a terminal complex when organizing unloading of an automobile transport by two loading means at one unloading station amounts to 23% compared to unloading at two stations.При определении параметров работы транспортно-складских комплексов возникает необходимость выбора критерия оптимизации. Разработана методика определения оптимальных параметров работы комплексов, включающая методы расчёта оптимального количества погрузочно-разгрузочных механизмов и постов. Результаты исследования показывают, что при расчётах оптимального количества погрузочно-разгрузочных механизмов и пунктов целесообразно учитывать соотношение интервалов приезда подвижного состава под погрузку, разгрузку и продолжительности нормативного времени работы одного разгрузочного механизма. Для определения оптимального количества погрузочноразгрузочных механизмов и постов в складских комплексах предложен критерий минимальных суммарных затрат транспортно-складских комплексов на выполнение погрузочно-разгрузочных операций и транспортных организаций в связи с простоем подвижного состава под погрузочно-разгрузочными работами. Определено, что экономия комплексных затрат транспортных компаний и терминального комплекса при организации разгрузки автотранспорта двумя погрузочными средствами на одном разгрузочном посту по сравнению с разгрузкой на двух постах составляет 23 %

Technical, economic and energetic competitiveness of rail-road combined transport: evaluation of the effects of possible ITS applications on intermodal terminal.

L'abstract è presente nell'allegato / the abstract is in the attachmen

Mixing quantitative and qualitative methods for sustainable transportation in Smart Cities

L'abstract è presente nell'allegato / the abstract is in the attachmen

VERIFICATION AND APPLICATION OF DETECTABILITY BASED ON PETRI NETS

In many real-world systems, due to limitations of sensors or constraints of the environment, the system dynamics is usually not perfectly known. However, the state information of the system is usually crucial for the purpose of decision making. The state of the system needs to be determined in many applications. Due to its importance, the state estimation problem has received considerable attention in the discrete event system (DES) community. Recently, the state estimation problem has been studied systematically in the framework of detectability. The detectability properties characterize the possibility to determine the current and the subsequent states of a system after the observation of a finite number of events generated by the system. To model and analyze practical systems, powerful DES models are needed to describe the different observation behaviors of the system. Secondly, due to the state explosion problem, analysis methods that rely on exhaustively enumerating all possible states are not applicable for practical systems. It is necessary to develop more efficient and achievable verification methods for detectability. Furthermore, in this thesis, efficient detectability verification methods using Petri nets are investigated, then detectability is extended to a more general definition (C-detectability) that only requires that a given set of crucial states can be distinguished from other states. Formal definitions and efficient verification methods for C-detectability properties are proposed. Finally, C-detectability is applied to the railway signal system to verify the feasibility of this property: 1. Four types of detectability are extended from finite automata to labeled Petri nets. In particular, strong detectability, weak detectability, periodically strong detectability, and periodically weak detectability are formally defined in labeled Petri nets. 2. Based on the notion of basis reachability graph (BRG), a practically efficient approach (the BRG-observer method) to verify the four detectability properties in bounded labeled Petri nets is proposed. Using basis markings, there is no need to enumerate all the markings that are consistent with an observation. It has been shown by other researchers that the size of the BRG is usually much smaller than the size of the reachability graph (RG). Thus, the method improves the analysis efficiency and avoids the state space explosion problem. 3. Three novel approaches for the verification of the strong detectability and periodically strong detectability are proposed, which use three different structures whose construction has a polynomial complexity. Moreover, rather than computing all cycles of the structure at hand, which is NP-hard, it is shown that strong detectability can be verified looking at the strongly connected components whose computation also has a polynomial complexity. As a result, they have lower computational complexity than other methods in the literature. 4. Detectability could be too restrictive in real applications. Thus, detectability is extended to C-detectability that only requires that a given set of crucial states can be distinguished from other states. Four types of C-detectability are defined in the framework of labeled Petri nets. Moreover, efficient approaches are proposed to verify such properties in the case of bounded labeled Petri net systems based on the BRG. 5. Finally, a general modeling framework of railway systems is presented for the states estimation using labeled Petri nets. Then, C-detectability is applied to railway signal systems to verify its feasibility in the real-world system. Taking the RBC handover procedure in the Chinese train control system level 3 (CTCS-3) as an example, the RBC handover procedure is modeled using labeled Petri nets. Then based on the proposed approaches, it is shown that that the RBC handover procedure satisfies strongly C-detectability

Decision Support System Approach for the Management of Complex Systems in Transportation and Logistics

L'analisi e la gestione dei sistemi complessi e delle loro ripercussioni in diversi aspetti della vita quotidiana sono tematiche che continuano ad attrarre molta attenzione nella letteratura scientifica. Si considerino, ad esempio, il trasporto marittimo e su strada, i moderni sistemi di assistenza sanitaria, le catene di distribuzione integrate, i processi industriali o, ancora, il nuovo paradigma di citt\ue0 intelligente: \ue8 evidente come in tutti questi contesti vi sia sempre pi\uf9 la necessit\ue0 di analizzare e gestire elementi eterogenei, collegati tra loro al fine di raggiungere un obiettivo comune altrimenti non realizzabile. Tuttavia, il processo decisionale in tali ambiti richiede competenze trasversali che abbracciano svariate discipline, rendendo la gestione di questi sistemi molto complessa e, spesso, inefficace. I Sistemi di Supporto alle Decisioni (DSS) ben si adattano alla previsione ed al controllo dei sistemi complessi grazie a: la loro capacit\ue0 di integrare varie fonti di dati ed informazioni; l'applicazione di modelli formali tipici di diverse discipline; la possibilit\ue0 di interagire costantemente con il sistema considerato. L'obiettivo di questo lavoro di tesi \ue8 quello di definire un approccio generale basato sul concetto di DSS per la gestione di sistemi complessi nel settore dei trasporti e della logistica, e di applicare tale approccio a tre problemi di grande interesse oggigiorno: 1) il problema della ricollocazione dei veicoli nei servizi di car sharing, 2) la gestione intelligente delle operazioni di carica dei veicoli elettrici presso le infrastrutture pubbliche e 3) l'ottimizzazione delle operazioni di drayage nel trasporto container. In particolare, il focus della ricerca \ue8 rivolto al cuore del DSS, ovvero alla parte che direttamente supporta il processo decisionale: i moduli di ottimizzazione e simulazione e le loro interazioni. Vengono considerati diversi approcci di modellazione, simulazione ed ottimizzazione, evidenziando il carattere totalmente generale dell' approccio considerato. I risultati ottenuti nelle diverse applicazioni sottolineano l'efficacia dei DSS nel migliorare il processo decisionale, portando ad un miglioramento generale delle prestazioni dei sistemi in esame. In particolare: 1) l'applicazione del DSS permette di ottimizzare i set-point per l'introduzione di un sistema di incentivi economici atto a risolvere il problema di ricollocazione dei veicoli nei servizi di car sharing, garantendo un miglioramento delle prestazioni del sistema, anche in condizioni di quasi saturazione; 2) il DSS permette la formalizzazione di un approccio leader-follower per il coordinamento delle operazioni di ricarica di veicoli elettrici che tenga conto contemporaneamente sia dei requisiti dell'utente che quelli della rete elettrica; infine, 3) il DSS consente di migliorare l'efficienza delle operazioni di drayage nel trasporto containter, riducendo i costi di trasporto.In recent years, the analysis and management of complex systems and their impacts in many aspects of the every-day life are topics that attract a lot of attention in the scientific literature. Consider for instance road and maritime transportation, modern healthcare systems, integrated supply chains, industrial processes or the new paradigm of smart cities: it is apparent that in all these contexts there is an increasing need of analysing and managing heterogeneous elements, networked together in order to reach a common goal otherwise not achievable. However, making decisions concerning such systems requires specific competences from many disciplines, leading to a very complex and often ineffective management process. Decision Support Systems (DSSs) can strengthen the capacity of predicting and controlling complex systems by integrating various sources of data and information, applying formal models typical of diverse and isolated disciplines and constantly interacting with the considered system. The goal of this work is to define a general approach based on the DSS concept for the management of complex systems in transportation and logistics and to apply it to three problems of great interest nowadays: 1) the user-based vehicle relocation problem} in car sharing services, 2) the smart management of electric vehicles charging operations and 3) the container drayage problem. In particular, the focus of the research is on the core of the DSS, i.e., on the part that directly supports the decision making process: optimization modules, simulation modules and their interactions. Different modelling, simulation and optimization approaches are applied, highlighting the generality of the considered approach regardless the specific context analysed. Results show the ability of DSSs to enhance the effectiveness of the decision process, thus leading to an improvement of the considered systems performance. In particular: 1) the application of the DSS allows to optimize the set-points of an incentive policy designed to solve the vehicle relocation problem in car sharing services, guaranteeing an effective relocation and improving the system performance even in the case of nearly saturated offer; 2) the DSS allows the formalization of a leader-follower approach for the coordination of electric vehicles charging operations which takes into account simultaneously electric grid and drivers requirements; finally, 3) the DSS allows to improve the efficiency of drayage operations in container transportation, reducing total transportation costs