In this paper we address the problem of chemical plume tracing using an autonomous underwater vehicle. We assume that turbulent water flow induces a random pattern of the readings of a binary (on off) sensor used to d...
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In this paper we address the problem of chemical plume tracing using an autonomous underwater vehicle. We assume that turbulent water flow induces a random pattern of the readings of a binary (on off) sensor used to detect the chemical being dispersed in the water. Our algorithm is completely sensor driven, not requiring idependent measures of the water flow direction and intensity. Instead, it relies on a stochastic model of the plume dispersion which is parametrised by the chemical source position, which we want to estimate, and by other nuisance parameters - comprising water flow - which are jointly estimated along with the desired source location. Instead of being based on a discrete controller that chains a series of perception driven behaviors, the mapping trajectory is chosen, at each step, as the direction along which the expected probability (given all data observed so far) of detecting the chemical is maximal.
作者：
E. BovioF. BaralliD. CecchiNATO Undersea Research Centre
Viale San Bartolomeo 400 19138 La Spezia (SP) ITALY ISME
Interuniversity Centre of Integrated System for Marine Environment c/o DSEA University of Pisa Via Diotisalvi 2 56126 Pisa Italy
Recognizing the potential of autonomous underwater vehicles for scientific and military applications, in 1997 MIT and the NATO Undersea Research Centre initiated a Joint Research Project (GOATS), for the development o...
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Recognizing the potential of autonomous underwater vehicles for scientific and military applications, in 1997 MIT and the NATO Undersea Research Centre initiated a Joint Research Project (GOATS), for the development of environmentally adaptive robotic technology applicable to Mine Counter Measures (MCM) and Rapid Environmental Assessment in coastal environments. The August 2001 GOATS Conference marked the end of this 5 years project, but did not mark the end of the work. The Centre initiated in 2002 a new long term programme to explore and demonstrate the operational benefits and limitations of AUV for covert preparation of the battlespace. Recently the work addressed the evaluation of COTS (Commercial Off-The-Shelf) AUV technology for MCM operations in response to terrorist mining of port. The paper summarizes the work performed and refers to the scientific publications derived from the AUV programme at the NATO Undersea Research Centre.
During chicken embryonic development the metanephros forms from the uretic duct at embryonic day (E) 7. As the metanephric tissue develops between E7 and E10, it comes into close apposition with lumbosacral nerves. Co...
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During chicken embryonic development the metanephros forms from the uretic duct at embryonic day (E) 7. As the metanephric tissue develops between E7 and E10, it comes into close apposition with lumbosacral nerves. Coculturing of metanephric and nerve explants demonstrated that the Schwann cells of the sciatic nerve inhibit the migration of metanephric cells in a contact-dependent manner. Conversely, metanephric cells inhibit dorsal root ganglion axon extension in a contact-dependent manner. However, metanephric cells are not inhibited by contact with growth cones or axons. Dorsal root ganglion growth cones become sensitive to the inhibitory signals on the surfaces of metanephric cells around E8, a time when the metanephros is expanding into the territory occupied by nerves in vivo. These observations demonstrate inhibitory bidirectional tissue-tissue interactions in vitro and provide a novel model system for the study of contact-based guidance of both neuronal and non-neuronal cell migration. (C) 2004 Wiley-Liss, Inc.
The Environment Assessment Directive of the European Union (EU) requires that the potential impacts on cultural heritage of proposed developments are examined. This paper considers how well cultural heritage is consid...
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Many real world design problems involve multiple, usually conflicting optimization criteria. Often, it is very difficult to weight the criteria exactly before alternatives are known. Multi-Objective Evolutionary Algor...
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Many real world design problems involve multiple, usually conflicting optimization criteria. Often, it is very difficult to weight the criteria exactly before alternatives are known. Multi-Objective Evolutionary Algorithms based on the principle of Pareto optimality are designed to explore the complete set of non-dominated solutions, which then allows the user to choose among many alternatives. However, although it is very difficult to exactly define the weighting of different optimization criteria, usually the user has some notion as to what range of weightings might be reasonable. In this paper, we present a novel, simple, and intuitive way to integrate the user's preference into the evolutionary algorithm by allowing to define linear maximum and minimum trade-off functions. On a number of test problems we show that the proposed algorithm efficiently guides the population towards the interesting region, allowing a faster convergence and a better coverage of this area of the Pareto optimal front. (C) 2001 Elsevier Science Ltd. All rights reserved.
Traditional approach for the design of missile guidance and autopilot systems has been to design these subsystems separately and then to integrate them. Such an approach does not exploit any beneficial relationships b...
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Traditional approach for the design of missile guidance and autopilot systems has been to design these subsystems separately and then to integrate them. Such an approach does not exploit any beneficial relationships between these and other subsystems. A technique for integrated design of missile guidance and autopilot systems using the feedback linearization technique is discussed. Numerical results using a six degree-of-freedom missile simulation are given. Integrated guidance-autopilot systems are expected to result in significant improvements in missile performance, leading to lower weight and enhanced lethality. These design methods have extensive applications in high performance aircraft autopilot and guidance system design. (C) 2001 Elsevier Science Ltd. All rights reserved.
It is now well established that the small GTPases of the Rho family - Rac, Cdc42 and Rho - regulate growth cone morphology, Less clear is their role in guiding the growth cone. Do they act permissively, providing the ...
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It is now well established that the small GTPases of the Rho family - Rac, Cdc42 and Rho - regulate growth cone morphology, Less clear is their role in guiding the growth cone. Do they act permissively, providing the dynamic actin structures needed for guidance? Or do they act instructively, transducing specific guidance signals? Recent studies have provided the first strong evidence for an instructive role: extracellular guidance cues can modulate Rho GTPase activities in vitro, and Rho GTPase activators function in growth cone guidance in vivo. The pathways linking Rho GTPases and the actin cytoskeleton are also rapidly coming into view, revealing further points of regulation by extracellular guidance cues. The growth cone is therefore guided by signals transduced both via and independently of Rho GTPases.
Dissociated neuronal cultures on substrates patterned with extracellular matrix (ECM) proteins have yielded much information regarding the physiological characteristics of neuronal cells behaviour in vitro. However, n...
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Dissociated neuronal cultures on substrates patterned with extracellular matrix (ECM) proteins have yielded much information regarding the physiological characteristics of neuronal cells behaviour in vitro. However, neuronal patterning using long term embryonic brain slice cultures has not been comprehensively demonstrated to-date. Structuring was performed by micro contact printing of laminin. The slice cultures were evaluated by means of phase contrast microscopy at 3-22 days in culture. We were able to consistently achieve outgrowth of neurons, neurites and filopodia from brain stem slices cultured on ECM proteins structures of grid- and line-shapes. We believe that brain slice cultures on patterned substrates is a favourable approach to study functional synapses in vitro under defined conditions. The use of appropriate structures and the subsequent cell patterning may help to gain further understanding of axonal, dendritic and synaptic signal transductions and processes. (C) 2001 Elsevier Science Ireland Ltd. All rights reserved.
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