A Survey on UAV-Aided Maritime Communications: Deployment Considerations, Applications, and Future Challenges

Maritime activities represent a major domain of economic growth with several emerging maritime Internet of Things use cases, such as smart ports, autonomous navigation, and ocean monitoring systems. The major enabler for this exciting ecosystem is the provision of broadband, low-delay, and reliable wireless coverage to the ever-increasing number of vessels, buoys, platforms, sensors, and actuators. Towards this end, the integration of unmanned aerial vehicles (UAVs) in maritime communications introduces an aerial dimension to wireless connectivity going above and beyond current deployments, which are mainly relying on shore-based base stations with limited coverage and satellite links with high latency. Considering the potential of UAV-aided wireless communications, this survey presents the state-of-the-art in UAV-aided maritime communications, which, in general, are based on both conventional optimization and machine-learning-aided approaches. More specifically, relevant UAV-based network architectures are discussed together with the role of their building blocks. Then, physical-layer, resource management, and cloud/edge computing and caching UAV-aided solutions in maritime environments are discussed and grouped based on their performance targets. Moreover, as UAVs are characterized by flexible deployment with high re-positioning capabilities, studies on UAV trajectory optimization for maritime applications are thoroughly discussed. In addition, aiming at shedding light on the current status of real-world deployments, experimental studies on UAV-aided maritime communications are presented and implementation details are given. Finally, several important open issues in the area of UAV-aided maritime communications are given, related to the integration of sixth generation (6G) advancements

Operationalising Ecologically Sustainable Development at the Micro Level Pareto Optimality and the Preservation of Biologically Crucial Levels.

The concept of Ecologically Sustainable Economic Development (ESED) has led to relentlessly heated debate. Yet, it still remains without a clear operational framework. At the micro level where a multitude of projects and programmes are designed, the absence of operational principles has serious repercussions. In order to tackle this ineffectiveness, ESED may be viewed as a pattern of economic process and evolution that takes into account the constraints imposed by the natural environment. In effect, the economic process should ensure the preservation of the human race by maintaining the biological basis responsible for the healthy evolution of the race. In addition, economic development should not lead to Pareto suboptimal positions by precluding production potentials. Based on these principles, the present paper outlines an operational framework for ESED at the micro level of projects and programmes. Copyright © 2006 Inderscience Enterprises Ltd

Valuating the receiving waters of urban wastewater systems through a stakeholder-based approach

The valuation of ecological services in European aquatic ecosystems is increasingly deemed to be an essential element for the integrated management concept pursued by the Water Framework Directive (2000/60/EC). However, the assessment methods are often doubted for their objectivity and transparency when based on the elicitation of stated preferences. The current research attempted to explicitly focus on the biases linked with the stakeholders participating in assessing methods operating with stated preferences. The most significant stakeholder groups were classified in three broad teams of Experts, DecisionMakers and Affected Professions. The three teams' preferences were in turn assessed in economic and non-economic terms for the accentuation of the high fluctuation among the findings, and the threatening biases emerged in the sourcing of stated preference methods. The wastewater treatment plant in Athens, Greece and Saronikos Bay offered a sound case study