4,873 research outputs found
Recovering from External Disturbances in Online Manipulation through State-Dependent Revertive Recovery Policies
Robots are increasingly entering uncertain and unstructured environments.
Within these, robots are bound to face unexpected external disturbances like
accidental human or tool collisions. Robots must develop the capacity to
respond to unexpected events. That is not only identifying the sudden anomaly,
but also deciding how to handle it. In this work, we contribute a recovery
policy that allows a robot to recovery from various anomalous scenarios across
different tasks and conditions in a consistent and robust fashion. The system
organizes tasks as a sequence of nodes composed of internal modules such as
motion generation and introspection. When an introspection module flags an
anomaly, the recovery strategy is triggered and reverts the task execution by
selecting a target node as a function of a state dependency chart. The new
skill allows the robot to overcome the effects of the external disturbance and
conclude the task. Our system recovers from accidental human and tool
collisions in a number of tasks. Of particular importance is the fact that we
test the robustness of the recovery system by triggering anomalies at each node
in the task graph showing robust recovery everywhere in the task. We also
trigger multiple and repeated anomalies at each of the nodes of the task
showing that the recovery system can consistently recover anywhere in the
presence of strong and pervasive anomalous conditions. Robust recovery systems
will be key enablers for long-term autonomy in robot systems. Supplemental info
including code, data, graphs, and result analysis can be found at [1].Comment: 8 pages, 8 figures, 1 tabl
Heterogeneous Strong Computation Migration
The continuous increase in performance requirements, for both scientific
computation and industry, motivates the need of a powerful computing
infrastructure. The Grid appeared as a solution for inexpensive execution of
heavy applications in a parallel and distributed manner. It allows combining
resources independently of their physical location and architecture to form a
global resource pool available to all grid users. However, grid environments
are highly unstable and unpredictable. Adaptability is a crucial issue in this
context, in order to guarantee an appropriate quality of service to users.
Migration is a technique frequently used for achieving adaptation. The
objective of this report is to survey the problem of strong migration in
heterogeneous environments like the grids', the related implementation issues
and the current solutions.Comment: This is the pre-peer reviewed version of the following article:
Milan\'es, A., Rodriguez, N. and Schulze, B. (2008), State of the art in
heterogeneous strong migration of computations. Concurrency and Computation:
Practice and Experience, 20: 1485-1508, which has been published in final
form at http://onlinelibrary.wiley.com/doi/10.1002/cpe.1287/abstrac
The limits of process: On (re)reading Henri Bergson
This article offers a reading of the work of Henri Bergson as it pertains to organizations through the lens of ideas drawn from critical realism. It suggests an alternative to interpretations based on a stark division between process and realist perspectives. Much of the existing literature presents a rather partial view of Bergson’s work. A review suggests some interesting parallels with themes in critical realism, notably the emergence of mind. Critical realism has a focus on process at its heart, but is also concerned with how the products of such processes become stabilized and form the conditions for action. This suggests that attention might usefully be paid to the relationship between organizational action and the sedimented practices grouped under the heading of ‘routines’. More attention to Bergson’s account of the relationship between instinct, intuition and intelligence provides a link to the social character of thought, something which can be mapped on to Archer’s work on reflexivity and the ‘internal conversation’. This suggests that our analyses need to pay attention to both memory and history, to building and dwelling, rather than the one-sided focus found in some process theory accounts
Virtual network security: threats, countermeasures, and challenges
Network virtualization has become increasingly prominent in recent years. It enables the creation of network infrastructures that are specifically tailored to the needs of distinct network applications and supports the instantiation of favorable environments for the development and evaluation of new architectures and protocols. Despite the wide applicability of network virtualization, the shared use of routing devices and communication channels leads to a series of security-related concerns. It is necessary to provide protection to virtual network infrastructures in order to enable their use in real, large scale environments. In this paper, we present an overview of the state of the art concerning virtual network security. We discuss the main challenges related to this kind of environment, some of the major threats, as well as solutions proposed in the literature that aim to deal with different security aspects.Network virtualization has become increasingly prominent in recent years. It enables the creation of network infrastructures that are specifically tailored to the needs of distinct network applications and supports the instantiation of favorable environme61CNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICORNP - REDE NACIONAL DE ENSINO E PESQUISAFAPERGS - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DO RIO GRANDE DO SULsem informaçãosem informaçãosem informaçã
Design, Implementation and Experiments for Moving Target Defense Framework
The traditional defensive security strategy for distributed systems employs well-established defensive techniques such as; redundancy/replications, firewalls, and encryption to prevent attackers from taking control of the system. However, given sufficient time and resources, all these methods can be defeated, especially when dealing with sophisticated attacks from advanced adversaries that leverage zero-day exploits
The modernist short story in Italy: the case of the 'Edizioni di Solaria'
This article investigates the role played by the modernist periodical Solaria (1926–34) as the Italian short story was being modernized. By offering a descriptive survey of the rarely studied corpus of fifteen short narrative volumes printed by the ‘Edizioni di Solaria’, the periodical’s minor publishing house, it sheds new light on the development of the short genre in this particular context. The two key questions addressed are, on the one hand, the validity of a recent hypothesis proposing Italo Svevo as a model for the ‘Solarian’ short story, and, on the other, the relationship between the codified novella/raccontoand other forms of short narrative prose derived from early twentieth-century avant-garde experimentation
Prospects for large-scale financial systems simulation
As the 21st century unfolds, we find ourselves having to control, support, manage or otherwise cope with large-scale complex adaptive systems to an extent that is unprecedented in human history. Whether we are concerned with issues of food security, infrastructural resilience, climate change, health care, web science, security, or financial stability, we face problems that combine scale, connectivity, adaptive dynamics, and criticality. Complex systems simulation is emerging as the key scientific tool for dealing with such complex adaptive systems. Although a relatively new paradigm, it is one that has already established a track record in fields as varied as ecology (Grimm and Railsback, 2005), transport (Nagel et al., 1999), neuroscience (Markram, 2006), and ICT (Bullock and Cliff, 2004). In this report, we consider the application of simulation methodologies to financial systems, assessing the prospects for continued progress in this line of research
Open agent systems???
E-institutions are envisioned as facilities on the Internet for heterogeneous software agents to perform their interactions and thus forming truly open agent systems. We investigate how these heterogeneous agents can determine whether an institution is one in which they can participate. We propose a layered approach which is supported through a (traditional) middle agent that is part of the environment. Starting with a basic compatibility of message types, each extra layer ensures a higher degree of compatibility, but requires also extra sophistication in both the information required and the matching algorithms. In this paper, we describe reasoning about how an agent should take on a specific role, message matching, and protocol compatibility. We explore the issues in the context of an actual accommodation agent built in JACK, and a travel agency institution built in ISLANDER
- …