Methodology for determining optimized traffic light cycles based on simulation

In large urbanized cities, a major problem that affects the economy and health of all citizens is vehicular congestion. This is because the traffic light cycles are not adequate. In the present study, we seek to optimize traffic light cycles based on simulation, in order to improve vehicle flow. For this, the PTV Vissim 9.0 software was used as a simulator and the Synchro 10.0 software to determine the initial optimal traffic light cycle. Through several runs and having as variables the length of queues, delay times and the average speed, the optimal traffic light cycle could be found for the study area. The results obtained reflect a 14% reduction in delay times and 10% in queue lengths. On the other hand, the average vehicle speed increased by 10.56%. All this represents an improvement in the service level of the study intersections

Luneburg lens in silicon photonics

The Luneburg lens is an aberration-free lens that focuses light from all directions equally well. We fabricated and tested a Luneburg lens in silicon photonics. Such fully-integrated lenses may become the building blocks of compact Fourier optics on chips. Furthermore, our fabrication technique is sufficiently versatile for making perfect imaging devices on silicon platforms. (C) 2011 Optical Society of AmericaPublisher PDFPeer reviewe

Evaluating flood risk governance with geospatial technologies

The concept of governance for flood resilience has gained traction in scholarship and practice over the last 15 years. Governance is distinct from government as it recognizes that flood risk management (FRM) is carried out by actors that transcend government and which include the private sector and civil society. Though there is a theoretical notion that effective FRM entails the involvement of a diverse set of actors and measures, there is a notable lack of studies on the development and evaluation of tools designed to foster greater integration between public and private actors to solve FRM problems of common concern. This dissertation primarily focuses on the Canadian context and the problem of residential properties that are high-risk and “uninsurable” for flood damages, and which are subject of current national public policy discourse. Current public policy discussions revolve around the relocation of these properties away from high-risk flood zones and establishing a public program for extending affordable flood insurance coverage to these higher risk properties. This dissertation focuses on an alternative strategy by evaluating the role that a public-private data-sharing partnership could play in reducing and managing the number of high-risk “uninsurable” properties. Through three interrelated studies, this dissertation demonstrates how, in the absence of a common approach to flood risk identification, insurers and municipalities have a conflicting understanding of which properties are at risk of flood. The lack of channels for information-exchange between municipalities and insurers are also prohibiting municipal officials from knowing why insurers classify a property as “high-risk”, while also posing difficulties for insurers to become aware of public flood risk mitigation investments happening across Canada. To foster collaboration between insurers and municipal officials for resolving the flood insurability problem, a data-sharing platform is proposed and evaluated via interviews with municipal officials and insurers. While this process of evaluation confirmed there is a “missing link” between municipalities and insurers, the proposed data platform faces many obstacles for its adoption and evidence gathered suggest it is unlikely to lead to greater availability and affordability of flood insurance products. Instead, findings support an appeal process that would establish a three-way communication line between insurers, government officials and individual homeowners who are experiencing issues finding affordable flood insurance coverage for their property. This process of appeal would (1) reveal the reasons why insurers classify a specific property as “high risk” of flood, (2) address modelling and technical limitations that may be influencing insurers’ risk classification such as the omission of flood protection infrastructure, (3) agree upon additional measures that could be implemented to reduce physical flood risk by either the homeowner and/or responsible government agencies that could further promote that flood insurance remains available and affordable to the homeowner. More broadly, this dissertation concludes that in a time of increasing economic losses from floods and climate risk uncertainties, a concerted multi-level government effort is necessary to collect data about flood protection infrastructure. This database can inform the process of appeal but it can also be used to raise awareness and provide confidence among civil society and the private sector about the effectiveness of public infrastructure investments in preventing flood damages. Finally, this dissertation presents novel approaches for evaluating flood risk governance that leverage geospatial data, methods and tools which could be replicated and tested in other international contexts

Supporting Local Climate Change Adaptation with the Participatory Geoweb: Findings from Coastal Nova Scotia

The effects of climate change have been detected in various natural systems in the last century (IPCC, 2014). As a consequence of these changes, governments are seeking to identify adaptive strategies for protecting citizens and vulnerable economic sectors (Adger et al., 2005; Smit & Wandel, 2006). Coastal areas are particularly susceptible to a changing climate as sea level continues to rise and storm surges become more powerful and frequent events. This research introduces the use of the participatory Geoweb as a tool (labelled “AdaptNS”) for supporting local climate change adaptation efforts in Shelburne County, Nova Scotia. AdaptNS serves as a visualization tool for displaying high-resolution interactive flood maps of sea level rise and storm surge scenarios between 2000 and 2100. The participatory aspect of this Geoweb tool is integrated as a means for decision-makers, stakeholders, and community members to identify adaptation priorities in response to climate change risks. This interdisciplinary approach was possible through the use of several technologies, including the Arcpy Python library for analysis, and a coupling of the Google Maps API and LAMP bundle for the front-end and back-end tool development. By using feedback from community members, AdaptNS was identified to support local adaptation by providing communities with comprehensive visuals of climate change risks, a platform for identifying adaptation priorities, and a means to communicate local risks to upper levels of government and businesses

Obstacle avoidance in aerial pursuit

Pursuing prey through clutter is a complex and risky activity requiring integration of guidance subsystems for obstacle avoidance and target pursuit. The unobstructed pursuit trajectories of Harris’ hawks Parabuteo unicinctus are well modeled by a mixed guidance law feeding back target deviation angle and line-of-sight rate. Here we ask how their pursuit behavior is modified in response to obstacles, using high-speed motion capture to reconstruct flight trajectories recorded during obstructed pursuit of maneuvering targets. We find that Harris’ hawks use the same mixed guidance law during obstructed pursuit but appear to superpose a discrete bias command that resets their flight direction to aim at a clearance of approximately one wing length from an upcoming obstacle as they reach some threshold distance from it. Combining a feedback command in response to target motion with a feedforward command in response to upcoming obstacles provides an effective means of prioritizing obstacle avoidance while remaining locked-on to a target. We therefore anticipate that a similar mechanism may be used in terrestrial and aquatic pursuit. The same biased guidance law could also be used for obstacle avoidance in drones designed to intercept other drones in clutter, or to navigate between fixed waypoints in urban environments