Conflict Resolution Schemes Research Articles

Tactical Conflict Solver Assisting Air Traffic Controllers Using Deep Reinforcement Learning

To assist air traffic controllers (ATCOs) in resolving tactical conflicts, this paper proposes a conflict detection and resolution mechanism for handling continuous traffic flow by adopting finite discrete actions to resolve conflicts. The tactical conflict solver (TCS) was developed based on deep reinforcement learning (DRL) to train a TCS agent with the actor–critic using a Kronecker-factored trust region. The agent’s actions are determined by the ATCOs’ instructions, such as altitude, speed, and heading adjustments. The reward function is designed in accordance with air traffic control regulations. Considering the uncertainty in a real-life situation, this study characterised the deviation of the aircraft’s estimated position to improve the feasibility of conflict resolution schemes. A DRL environment was developed with the actual airspace structure and traffic density of the air traffic operation simulation system. Results show that for 1000 test samples, the trained TCS could resolve 87.1% of the samples. The conflict resolution rate decreased slightly to 81.2% when the airspace density was increased by a factor of 1.4. This research can be applied to intelligent decision-making systems for air traffic control.

Raze policy conflicts in SDN

Software Defined Networking (SDN) enables flexible network management with a well-defined abstraction between control and data plane. In this way, operators could issue the policies, e.g., forwarding path, flow counting and rate limiting, from the control plane, which will be enforced by the flow table rules in the data plane. However, multiple active policies with the same priority will potentially trigger conflicts among policies with overlapped flow space, causing the flow table explosion. In contrast to the local switch conflict resolution schemes proposed by previous works, this paper tackles the same problem from a different angle and resolves the policy conflict problem by coordinating all switches under a global centralized view. Specifically, we propose COnflict RAzor (CORA), which tremendously reduces the storage cost of conflicting policies leveraging the global network information obtained in the controller. The basic idea of CORA is migrating policies causing large explosions across the network if necessary, while keeping the semantics equivalence. We prove CORA’s NP hardness and propose a heuristic to efficiently search a near-optimal policy migration strategy. Our experiments demonstrate that, CORA can effectively reduce the flow table storage occupation by averagely 79.8% within less than 40 s, which is 47.9% more efficient than the state-of-the-art.

Why Do Large Infrastructure Projects Often Fail?

The paper reports, in a systematic manner, the views of a group of experienced practitioners on why large infrastructure projects often fail. The views, centering on the role played by the Owner (the Client or Buyer), can be summarized as follows:The owner should be aware of the need of clarity when it comes to own priorities, requirements, decision making authority, and risk allocation, and such clarity together with measures intended to secure a cooperative spirit, including a balanced sharing of risk and conflict resolution schemes that secure a quick resolution of conflicts, are central elements in securing successful projects.

Beneficial mediated communication in cheap talk

This paper investigates mediated communication between an informed sender and an uninformed receiver with conflicting preferences in the framework of Crawford and Sobel (1982). It provides a simple condition for mediation to be beneficial, that is, to give the receiver a higher ex-ante payoff than the uninformed decision. This condition in turn allows us to identify scenarios in which mediation is beneficial while all cheap-talk equilibria are uninformative. Our condition extends the conditions for beneficial mediation with a binary type space (Mitusch and Strausz, 2005) and mediation via a biased mediator (Ambrus et al., 2013). Finally, we show the connection between the identified condition and related conditions in other conflict resolution schemes: delegation (Alonso and Matouschek, 2008) and arbitration (Kovác and Mylovanov, 2009).

Breaking the Dynamics of Emotions and Fear in Conflict and Reconstruction

AbstractThis paper is all about the construction of a new analytical framework to understand conflict and cooperation both at the international and at the domestic level with the aim of then finding mechanisms to reduce tensions and initiate conflict resolution schemes. The existing research literature on such analytical frameworks has so far been conducted a) mostly on standard social science disciplinary lines and has not incorporated the important work done on these questions by neuro-scientists and behavioral geneticists and b) is not really capable except in very specific instances to deal with the evolving dynamics of conflict and cooperation. Conflict over scarce resources (territory, mates, food) between members of the same species is a universal feature of evolution. Often conflict, especially armed conflict is supposed to be due to shows of force by two or more parties in order to appropriate or dominate resources. Force appears thus not to be the only decisive factor; perceived entitlement and powerful feelings of injustice thereby generated in the case of challenge, extended to group identity are also at the basis of conflict and aggression in humans. The relationship between environment and conflict, the role of emotions such as fear, and the absence of clear definition and enforcement of property rights within societies are also factors in the development of conflict. Thus we have here developed an analytically based numerical model that aims to include finding on these topics by Neuroscience and to emphasize the role of emotions in conflict and cooperation dynamics. This model has been simulated without specific reference to a particular country with the result that economic conditions drive our system since in one case sustained growth produces stability and end of combats whereas deteriorating capital growth and GDP collapse lead to increased hostile coalition participation and more fighting. However, the mere trigger of economic conditions is insufficient to explain conflict escalation, which results from increased participation in mutually hostile coalitions and greater fighting propensity where emotions such as fear and resentment play their role. Finally a detailed empirical analysis of the current Syrian conflict has been undertaken which shows the ability of the model to forecast actual historical developments. This study also indicates that worsening economic conditions are not the only triggering factors in civil conflict. Perceptions of opportunities due to a weakening of a regime’s authority also play a major role.

Improved Multi-Aircraft Ground Trajectory Predictionfor Air Traffic Control

Accurate trajectory prediction plays a fundamental role in advanced air traffic control operations, because it forms the basis for (among others) conflict detection and resolution schemes. It has been demonstrated that improved trajectory prediction accuracy can be achieved using radar measurements for a single aircraft, but the benefits are expected to be much greater if one can fuse measurements from multiple aircraft at different locations and time instants. It is shown here how this multi-aircraft sensor fusion problem can be formulated as a high-dimensional state estimation problem. A novel particle filtering algorithm is developed to solve it in realistic scale situations. By exploiting the structure of the problem, one can address the technical challenges that arise in the process: efficiently handling the information, dealing with the estimation of a very high-dimensional state, and dealing with the nonlinear dynamics of aircraft motion and control. The effectiveness of the novel algorithms is demonstrated on feasibility studies involving multiple aircraft (from one to several hundred). The studies show that in the presence of multiple aircraft the trajectory prediction results approach the theoretical limit ofaccuracy under these conditions.

Performance Evaluation of Airborne Separation Assurance for Free Flight

Airborne separation assurance is a key requirement for free flight operations. This paper investigates the feasibility of airborne separation assurance for free flight by evaluating the performance of Conflict Detection and Resolution (CD&R) schemes in a simulated air traffic environment. Two qualitatively different CD&R methods were evaluated in an air traffic simulation environment provided by the Future ATM Concepts Evaluation Tool (FACET). The evaluation was based on a horizontal-plane free flight traffic scenario constructed with initial conditions from actual air traffic data; nearly a thousand aircraft were modeled in this 6-hour scenario. The results of the performance evaluation indicate that airborne separation assurance performed quite well in the free flight evaluations: (1) All of the conflicts were resolved; (2) The impact on flight efficiency, as measured by path-length and flight-time changes, was quite small; and, (3) The impact on system stability, as measured by additional aircraft experiencing conflicts due to the “domino effect,” was modest.

A general discusion on national forest programmes

This paper mainly reviews the NFP process, as discussed by the IPF panel and European workshops in this field. It focuses on three issues i) basic terms, objectives and principles or elements of the concept NFP, ii) evaluation of national forest programmes, with justification, strengths and weaknesses, iii) implementation of NFPs, including requirements for success. Finally gaps in NFPs and priorities for future action are discussed. During the last years national forest programmes have received considerable attention as the reference framework for sustainable management. The following elements are considered as the most important: 1) participatory mechanisms 2) holistic and inter-sectoral approaches 3) national sovereignty 4) long term and iterative process 5) capacity building 6) effective co-ordination and conflict resolution schemes. A specific conclusion, which already can be drawn, proves that procedural instruments are too weak to achieve the NFP's objectives. Generally the following three limiting factors are recognised: funding, institutional capacity and co-ordination among all interested parties at the national and international level. However, the fact that issues of forest policy are back on the political agenda is seen as very advantageous. The overall conclusion is that the NFP process is far from rooted in national forest policies. The major problem is the vagueness of the term. Further clarification of the meanings and dimensions of the elements and principles is required.

A probabilistic approach to aircraft conflict detection

Conflict detection and resolution schemes operating at the mid-range and short-range level of the air traffic management process are discussed. Probabilistic models for predicting the aircraft position in the near-term and mid-term future are developed. Based on the mid-term prediction model, the maximum instantaneous probability of conflict is proposed as a criticality measure for two aircraft encounters. Randomized algorithms are introduced to efficiently estimate this measure of criticality and provide quantitative bounds on the level of approximation introduced. For short-term detection, approximate closed-form analytical expressions for the probability of conflict are obtained, using the short-term prediction model. Based on these expressions, an algorithm for decentralized conflict detection and resolution that generalizes potential fields methods for path planning to a probabilistic dynamic environment is proposed. The algorithms are validated using Monte Carlo simulations.

Simulative study on the performance improvement of conflict resolution schemes in Manhattan Street Network

A simple node structure is essential in the design of multi-hop wave division multiplexing (WDM) networks to process packets immediately, when it acts in a high speed environment running at over 1 Gbps, and an effective routing mechanism is required to improve network performance. In this paper, we compare the performance of deflection routing with that of store-and-forward routing in the Manhattan Street Network (MSN), which is one of the typical multi-hop WDM networks. We also propose three conflict resolution schemes for the deflection routing and compare their performances, including the existing random selection scheme, which does not strictly adopt the conflict resolution mechanism. The results show that all the proposed schemes lead to substantial performance improvement over the random selection scheme; in particular, the scheme which prefers the packet with the minimum distance to the destination presents the best performance.

Dynamic analysis of timed Petri nets: a case of two processes and a shared resource

There are several techniques for the analysis of the dynamics of timed Petri nets. When the net is not decision free, the existing methods come short of an efficient analysis. In this paper, we present a method, we call "relative temporal analysis", to analyze the dynamics of a system with two processes and a shared resource. It is possible to find the resource utilization sequence, the waiting time period for each process and identify possible conflicts through this technique. Based on this technique we also build control charts which can be used for control purposes such as obtaining "optimal" conflict resolution schemes.

Improving Subjective Probability Assessment for Planning and Control in Team-Like Organizations

Improving Subjective Probability Assessment for Planning and Control in Team-Like Organizations