Learning Multirobot Hose Transportation and Deployment by Distributed Round-Robin Q-Learning

Multi-Agent Reinforcement Learning (MARL) algorithms face two main difficulties: the curse of dimensionality, and environment non-stationarity due to the independent learning processes carried out by the agents concurrently. In this paper we formalize and prove the convergence of a Distributed Round Robin Q-learning (D-RR-QL) algorithm for cooperative systems. The computational complexity of this algorithm increases linearly with the number of agents. Moreover, it eliminates environment non sta tionarity by carrying a round-robin scheduling of the action selection and execution. That this learning scheme allows the implementation of Modular State-Action Vetoes (MSAV) in cooperative multi-agent systems, which speeds up learning convergence in over-constrained systems by vetoing state-action pairs which lead to undesired termination states (UTS) in the relevant state-action subspace. Each agent's local state-action value function learning is an independent process, including the MSAV policies. Coordination of locally optimal policies to obtain the global optimal joint policy is achieved by a greedy selection procedure using message passing. We show that D-RR-QL improves over state-of-the-art approaches, such as Distributed Q-Learning, Team Q-Learning and Coordinated Reinforcement Learning in a paradigmatic Linked Multi-Component Robotic System (L-MCRS) control problem: the hose transportation task. L-MCRS are over-constrained systems with many UTS induced by the interaction of the passive linking element and the active mobile robots.

An Assessment Of The Economic Impact Of Climate Change On The Transportation Sector In Montserrat

.--I. Introduction.--II. Literature review regarding climate change impacts on international transportation.--III. Economy of the Caribbean subregion and Monserrat.--IV. The international transportaion system in the Caribbean and in Monserrat.--V. Vulnerabilities of international transport system in Monserrat to climate change.--VI. Modelling.-- VII. Economic impact analysis of climate chage on the international transport.-- VIII. Approaches to mitigation and adaptation in the air and sea transportation sectors.-- IX. Conclusions

Endemic tuberculosis, the homeless, and public transportation: A merging of geographical information systems surveillance and the Houston Tuberculosis Initiative Surveillance project

To reach the goals established by the Institute of Medicine (IOM) and the Centers for Disease Control's (CDC) STOP TB USA, measures must be taken to curtail a future peak in Tuberculosis (TB) incidence and speed the currently stagnant rate of TB elimination. Both efforts will require, at minimum, the consideration and understanding of the third dimension of TB transmission: the location-based spread of an airborne pathogen among persons known and unknown to each other. This consideration will require an elucidation of the areas within the U.S. that have endemic TB. The Houston Tuberculosis Initiative (HTI) was a population-based active surveillance of confirmed Houston/Harris County TB cases from 1995–2004. Strengths in this dataset include the molecular characterization of laboratory confirmed cases, the collection of geographic locations (including home addresses) frequented by cases, and the HTI time period that parallels a decline in TB incidence in the United States (U.S.). The HTI dataset was used in this secondary data analysis to implement a GIS analysis of TB cases, the locations frequented by cases, and their association with risk factors associated with TB transmission. ^ This study reports, for the first time, the incidence of TB among the homeless in Houston, Texas. The homeless are an at-risk population for TB disease, yet they are also a population whose TB incidence has been unknown and unreported due to their non-enumeration. The first section of this dissertation identifies local areas in Houston with endemic TB disease. Many Houston TB cases who reported living in these endemic areas also share the TB risk factor of current or recent homelessness. Merging the 2004–2005 Houston enumeration of the homeless with historical HTI surveillance data of TB cases in Houston enabled this first-time report of TB risk among the homeless in Houston. The homeless were more likely to be US-born, belong to a genotypic cluster, and belong to a cluster of a larger size. The calculated average incidence among homeless persons was 411/100,000, compared to 9.5/100,000 among housed. These alarming rates are not driven by a co-infection but by social determinants. The unsheltered persons were hospitalized more days and required more follow-up time by staff than those who reported a steady housing situation. The homeless are a specific example of the increased targeting of prevention dollars that could occur if TB rates were reported for specific areas with known health disparities rather than as a generalized rate normalized over a diverse population. ^ It has been estimated that 27% of Houstonians use public transportation. The city layout allows bus routes to run like veins connecting even the most diverse of populations within the metropolitan area. Secondary data analysis of frequent bus use (defined as riding a route weekly) among TB cases was assessed for its relationship with known TB risk factors. The spatial distribution of genotypic clusters associated with bus use was assessed, along with the reported routes and epidemiologic-links among cases belonging to the identified clusters. ^ TB cases who reported frequent bus use were more likely to have demographic and social risk factors associated with poverty, immune suppression and health disparities. An equal proportion of bus riders and non-bus riders were cultured for Mycobacterium tuberculosis, yet 75% of bus riders were genotypically clustered, indicating recent transmission, compared to 56% of non-bus riders (OR=2.4, 95%CI(2.0, 2.8), p<0.001). Bus riders had a mean cluster size of 50.14 vs. 28.9 (p<0.001). Second order spatial analysis of clustered fingerprint 2 (n=122), a Beijing family cluster, revealed geographic clustering among cases based on their report of bus use. Univariate and multivariate analysis of routes reported by cases belonging to these clusters found that 10 of the 14 clusters were associated with use. Individual Metro routes, including one route servicing the local hospitals, were found to be risk factors for belonging to a cluster shown to be endemic in Houston. The routes themselves geographically connect the census tracts previously identified as having endemic TB. 78% (15/23) of Houston Metro routes investigated had one or more print groups reporting frequent use for every HTI study year. We present data on three specific but clonally related print groups and show that bus-use is clustered in time by route and is the only known link between cases in one of the three prints: print 22. (Abstract shortened by UMI.)^

Application of active and passive suspension techniques to improve high speed ground vehicle performance - phase II. Final report.

Transportation Department, Office of University Research, Washington, D.C.

Field evaluation of innovative active warning devices for use at railroad-highway grade crossings /

"August 1988."

Motorists' requirements for active grade crossing warning devices /

Mode of access: Internet.

Pilot Study on Improving the Efficiency of Transportation Projects Using Laser Scanning, 2003

Laser scanning is a terrestrial laser-imaging system that creates highly accurate three-dimensional images of objects for use in standard computer-aided design software packages. This report describes results of a pilot study to investigate the use of laser scanning for transportation applications in Iowa. After an initial training period on the use of the scanner and Cyclone software, pilot tests were performed on the following projects: intersection and railroad bridge for training purposes; section of highway to determine elevation accuracy and pair of bridges to determine level of detail that can be captured; new concrete pavement to determine smoothness; bridge beams to determine camber for deck-loading calculations; stockpile to determine volume; and borrow pit to determine volume. Results show that it is possible to obtain 2-6 mm precision with the laser scanner as claimed by the manufacturer compared to approximately one-inch precision with aerial photogrammetry using a helicopter. A cost comparison between helicopter photogrammetry and laser scanning showed that laser scanning was approximately 30 percent higher in cost depending on assumptions. Laser scanning can become more competitive to helicopter photogrammetry by elevating the scanner on a boom truck and capturing both sides of a divided roadway at the same time. Two- and three-dimensional drawings were created in MicroStation for one of the scanned highway bridges. It was demonstrated that it is possible to create such drawings within the accuracy of this technology. It was discovered that a significant amount of time is necessary to convert point cloud images into drawings. As this technology matures, this task should become less time consuming. It appears that laser scanning technology does indeed have a place in the Iowa Department of Transportation design and construction toolbox. Based on results from this study, laser scanning can be used cost effectively for preliminary surveys to develop TIN meshes of roadway surfaces. It also appears that this technique can be used quite effectively to measure bridge beam camber in a safer and quicker fashion compared to conventional approaches. Volume calculations are also possible using laser scanning. It seems that measuring quantities of rock could be an area where this technology would be quite beneficial since accuracy is more important with this material compared to soil. Other applications for laser scanning could include developing as-built drawings of historical structures such as the bridges of Madison County. This technology could also be useful where safety is a concern such as accurately measuring the surface of a highway active with traffic or scanning the underside of a bridge damaged by a truck. It is recommended that the Iowa Department of Transportation initially rent the scanner when it is needed and purchase the software. With time, it may be cost justifiable to purchase the scanner as well. Laser scanning consultants can be hired as well but at a higher cost.

Growth and Public Transportation Investments: Growth Management Strategies to Reduce Transportation Capital Costs In and Near Midwestern Urban Areas, 1995

Transportation and land-use are independent, inter-active systems. Land-use patterns shape local transportation demand, but transportation systems in turn influence land-use patterns. In attempting to satisfy transportation demand created by existing land-use patterns, transportation planners directly, if not always consciously or intentionally, influence future land-use patterns. This study examines that complex relationship. The purpose of the study was threefold: to compile the body of knowledge already existing; to apply this body of knowledge to the context of midsize cities in the Midwest; and, to make the knowledge accessible both to transportation planners and to public officials who make key decisions about land use.

FY2010 Annual Report Research, Intelligent Transportation Systems, and Technology Transfer Activities, October 18, 2011

Transportation research makes a difference for Iowans and the nation. Implementation of cost effective research projects contributes to a transportation network that is safer, more efficient, and longer lasting. Working in cooperation with our partners from universities, industry, other states, and FHWA, as well as participation in the Transportation Research Board (TRB), provides benefits for every facet of the DOT. This allows us to serve our communities and the traveling public more effectively. Pooled fund projects allow leveraging of funds for higher returns on investments. In 2010, Iowa led fifteen active pooled fund studies, participated in twenty-two others, and was wrapping-up, reconciling, and closing out an additional 6 Iowa Led pooled fund studies. In addition, non-pooled fund SPR projects included approximately 20 continued, 9 new, and over a dozen reoccurring initiatives such as the technical transfer/training program. Additional research is managed and conducted by the Office of Traffic and Safety and other departments in the Iowa DOT.

Experimentation of mitigation techniques to reduce the effects of permafrost degradation on transportation infrastructures at Beaver Creek experimental road site, Alaska Highway, Yukon

Les méthodes de design et de construction des routes développés dans le sud canadien ont maintenant besoin d’être adaptés aux environnements nordiques du pays afin de prévenir le dégel dramatique du pergélisol lors de la construction d’une nouvelle route. De plus, le réchauffement climatique occasionne présentement d’importants problèmes de stabilité des sols dans le nord canadien. Ces facteurs causent des pertes importantes au niveau des capacités fonctionnelles et structurales de l’Alaska Highway au Yukon sur un segment de plus de 200 km situé entre le village de Destruction Bay et la frontière de l’Alaska. Afin de trouver des solutions rentables à long terme, le ministère du transport du Yukon (en collaboration avec le Federal Highway Administration du gouvernement américain, Transports Canada, l’Université Laval, l’Université de Montréal et l’Alaska University transportation Center) a mis en place 12 sections d’essais de 50 mètres de longueur sur l’autoroute de l’Alaska près de Beaver Creek en 2008. Ces différentes sections d’essais ont été conçues pour évaluer une ou plusieurs méthodes combinées de stabilisation thermique telles que le drain thermique, le remblai à convection d’air, le pare-neige / pare-soleil, le remblai couvert de matières organiques, les drains longitudinaux, le déblaiement de la neige sur les pentes et la surface réfléchissante. Les objectifs spécifiques de la recherche sont 1) d’établir les régimes thermiques et les flux de chaleur dans chacune des sections pour les 3 premières années de fonctionnement ; 2) de documenter les facteurs pouvant favoriser ou nuire à l’efficacité des systèmes de protection et ; 3) de déterminer le rapport coûts/bénéfices à long terme pour chacune des techniques utilisées. Pour ce faire, une nouvelle méthode d’analyse, basée sur la mesure de flux d’extraction de chaleur Hx et d’induction Hi à l’interface entre le remblai et le sol naturel, a été utilisée dans cette étude. Certaines techniques de protection du pergélisol démontrent un bon potentiel durant leurs 3 premières années de fonctionnement. C’est le cas pour le remblai à convection d’air non-couvert, le remblai à convection d’air pleine largeur, les drains longitudinaux, le pare-soleil / pare-neige et la surface réfléchissante. Malheureusement, des problèmes dans l’installation des drains thermiques ont empêché une évaluation complète de leur efficacité.