Urban Air Mobility: Viability of Hub-Door and Door-Door Movement by Air

Owing to a century of innovation in connected and automated aircraft design, for the rst time in history, air transport presents a potential competitive alternative to road, for hub-to-door and door-to-door urban services. In this article, we study the viability of air transport, for moving people and goods in an urban area, based on three metrics - enroute travel time, fuel cost and carbon dioxide (CO2) emissions. We estimate the metrics from emission standards and operational assumptions on vehicles based on current market data and compare electric air travel to gasoline road travel. For passenger movement, air is faster than road for all distances. It fares better on fuel cost and emissions only for longer distances (specic transition distances are stated in the text). For consolidated movement of goods, air is at par with road. Finally, for movement of unconsolidated goods, air again fares better than road on all three metrics. It is also noteworthy that these results are based on a road friendly urban design. Changes in design that facilitate easier access to air based hub-to-door and door-to-door services, would only make the case stronger for Urban Air Mobility (UAM), especially with connected and automated aircraft, as the next revolution in urban transportation

ECOLOGICAL-ECONOMIC MODELING ON A WATERSHED BASIS: A CASE STUDY OF THE CACHE RIVER OF SOUTHERN ILLINOIS

A digitally represented watershed landscape (ARC/INFO GIS) is merged with farm optimization (linear programming) and sediment and chemical transport (AGNPS) models. Enhanced targeting of non-point source pollution to remedial policy and management initiatives result. The implications of which are linked back to farm income and forward to the managed ecosystem.Environmental Economics and Policy, Research and Development/Tech Change/Emerging Technologies,

Integrating landscapes that have experienced rural depopulation and ecological homogenization into tropical conservation planning

If current trends of declining fertility rates and increasing abandonment of rural land as a result of urbanization continue, this will signal a globally significant transformation with important consequences for policy makers interested in conservation planning. This transformation is presently evident in a number of countries and projections suggest it may occur in the future in many developing countries. We use rates of population growth and urbanization to project population trends in rural areas for 25 example countries. Our projections indicate a general decline in population density that has either occurred already (e.g., Mexico) or may occur in the future if current trends continue (e.g., Uganda). Using both temperate and tropical examples we present evidence that this process will lead to ecological homogenization as a dominant habitat (e.g., forest replaces a mosaic of human-maintained landscapes), resulting in declines in biodiversity at the local scale. Building on this information, we consider research programs that need to be conducted so that policy makers are prepared to effectively manage depopulated rural areas

REGIONAL ECONOMIC IMPACTS OF A WATERSHED PLANNING PROCESS TO REDUCE EROSION AND STREAM SEDIMENTATION

Farm-level and watershed-wide land-use changes resulting from policy initiatives are linked to a regional input/output model. As a result not only can the direct economic impacts at the farm and watershed levels be determined, so too can the direct and induced economic impacts at the regional level.Resource /Energy Economics and Policy,

Distributing synchronous systems with modular structure

Abstract—Synchronous programs were introduced to sim-plify the development of reactive systems hiding the complexity and indeterminism of the interleaving while taking full ad-vantage of possible concurrency. The introduction of commu-nication networks enabled the creation of distributed systems presenting the programmer with a new burden of interleaving and non determinism due to the asynchronous communication medium. Again this complexity should be hidden from the user while taking full advantage of the possible concurrency to improve performance. Many algorithms for the automatic distributions of synchronous programs have been proposed so far, but they are not suitable for large scale system because they do not preserve the compositionality of the original code: the modularity of the synchronous program is lost. As a result the subsystems are not re-usable and a small local change results in the recompilation and re-distribution of the overall system. This solution is cumbersome and unpractical in many real-world applications. In this paper we introduce an algorithm for the distribution of synchronous programs that preserves the modularity and allows separate compilation and subsystem re-use. I

Evaluating eVTOL Network Performance and Fleet Dynamics through Simulation-Based Analysis

Urban Air Mobility (UAM) represents a promising solution for future transportation. In this study, we introduce VertiSim, an advanced event-driven simulator developed to evaluate e-VTOL transportation networks. Uniquely, VertiSim simultaneously models passenger, aircraft, and energy flows, reflecting the interrelated complexities of UAM systems. We utilized VertiSim to assess 19 operational scenarios serving a daily demand for 2,834 passengers with varying fleet sizes and vertiport distances. The study aims to support stakeholders in making informed decisions about fleet size, network design, and infrastructure development by understanding tradeoffs in passenger delay time, operational costs, and fleet utilization. Our simulations, guided by a heuristic dispatch and charge policy, indicate that fleet size significantly influences passenger delay and energy consumption within UAM networks. We find that increasing the fleet size can reduce average passenger delays, but this comes at the cost of higher operational expenses due to an increase in the number of repositioning flights. Additionally, our analysis highlights how vertiport distances impact fleet utilization: longer distances result in reduced total idle time and increased cruise and charge times, leading to more efficient fleet utilization but also longer passenger delays. These findings are important for UAM network planning, especially in balancing fleet size with vertiport capacity and operational costs. Simulator demo is available at: https://tinyurl.com/vertisim-visComment: Accepted to AIAA SciTech Forum 202

Ecoregional Dominance in Spatial Distribution of Avian Influenza (H5N1) Outbreaks

Recent articles in Emerging Infectious Diseases (1,2) and elsewhere (3,4) have highlighted the role of Anatidae migration in dispersal of the H5N1 subtype of highly pathogenic avian influenza (HPAI) virus. Although these articles point out that identifying the geographic origin of migrating waterfowl is needed to understand and predict pathogen dispersal, study analyses have been limited to pathways with nominal reference to climatic and vegetation patterns that control spatiotemporal patterns of this migration