11,211 research outputs found
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A parallel genetic algorithm for the Steiner Problem in Networks
This paper presents a parallel genetic algorithm to the
Steiner Problem in Networks. Several previous papers
have proposed the adoption of GAs and others
metaheuristics to solve the SPN demonstrating the
validity of their approaches. This work differs from them
for two main reasons: the dimension and the
characteristics of the networks adopted in the experiments
and the aim from which it has been originated. The reason
that aimed this work was namely to build a comparison
term for validating deterministic and computationally
inexpensive algorithms which can be used in practical
engineering applications, such as the multicast
transmission in the Internet. On the other hand, the large
dimensions of our sample networks require the adoption
of a parallel implementation of the Steiner GA, which is
able to deal with such large problem instances
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Active networks: an evolution of the internet
Active Networks can be seen as an evolution of the classical model of packet-switched networks. The traditional and âpassiveâ network model is based on a static definition of the network node behaviour. Active Networks propose an âactiveâ model where the intermediate nodes (switches and routers) can load and execute user code contained in the data units (packets). Active Networks are a programmable network model, where bandwidth and computation are both considered shared network resources. This approach opens up new interesting research fields. This paper gives a short introduction of Active
Networks, discusses the advantages they introduce and presents the research advances in this field
Translation and adaptation of an international questionnaire to measure usage of complementary and alternative medicine (I-CAM-G)
BACKGROUND: The growing body of data on prevalence of complementary and alternative medicine (CAM) usage means there is a need to standardize measurement on an international level. An international team has published a questionnaire0020 (I-CAM-Q), but no validation has yet been provided. The aim of the present study was to provide a German measurement instrument for CAM usage (I-CAM-G) which closely resembles the original English version, and to assess it's performance in two potential samples for measuring CAM usage.
METHODS: The English I-CAM-Q questionnaire was translated into German, and adapted slightly. The resulting I-CAM-G questionnaire was then pre-tested on N=16 healthy volunteers, and 12 cognitive interviews were carried out. The questionnaire was employed in a sample of breast cancer patients (N=92, paper and pencil), and a sample from the general population (N=210, internet survey). Descriptive analyses of items and missing data, as well as results from the cognitive interviews, are presented in this paper.
RESULTS: The translated questionnaire had to be adapted to be consistent with the German health care system. All items were comprehensible, whereby some items were unambiguous (e.g. CAM use yes/no, helpfulness), while others gave rise to ambiguous answers (e.g. reasons for CAM use), or high rates of missing data (e.g. number of times the CAM modality had been used during the last 3 months). 78% of the breast cancer patients and up to 85% of a sample of the general population had used some form of CAM.
CONCLUSIONS: Following methodologically sound and comprehensive translation, adaptation and assessment processes using recognized translation procedures, cognitive interviews, and studying the performance of the questionnaire in two samples, we arrived at a German questionnaire for measuring CAM use which is comparable with the international (English) version. The questionnaire appropriately measures CAM use, with some items being more appropriate than others. We recommend the development of a short version
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A fuzzy approach for the network congestion problem
In the recent years, the unpredictable growth of the Internet has moreover pointed out the congestion problem, one of the problems that historicallyha ve affected the network. This paper deals with the design and the evaluation of a congestion control algorithm which adopts
a FuzzyCon troller. The analogyb etween Proportional Integral (PI) regulators and Fuzzycon trollers is discussed and a method to determine the scaling factors of the Fuzzycon troller is presented. It is shown that
the Fuzzycon troller outperforms the PI under traffic conditions which are different from those related to the operating point considered in the design
LâinformalitĂ del cambiamento urbano. Pratiche e progettualitĂ dellâabitare nel quartiere San Berillo di Catania
This ethnographic research focuses on the informal activities that take place in the streets of the San Berillo neighbourhood in the historical centre of the city of Catania, highlighting the stories and meanings that are linked to these uses as a production of transformation and planning. Urban regeneration is an important resource to improve the urban quality, but this process can be produce marginalization and displacement process in the city context. Rethinking the city by expanding the elements of reference, it means recognizing in the urban practices, in the meanings from the bottom and in the symbolic dimension, interpretive categories endowed with planning. Urban practices play a decisive role in the construction of the city. Although they are often more easily associated with abusivism, they constitute the fundamental and prevailing modalities of urban development. The city is not given only by a constructive process of physical space but is the result of adaptation and appropriation of spaces to redefine their uses
The glowing screen before me and the moral law within me : a Kantian duty against screen overexposure
This research was supported by the Russian Academic Excellence Project at the Immanuel Kant Baltic Federal University.This paper establishes a Kantian duty against screen overexposure. After defining screen exposure, I adopt a Kantian approach to its morality on the ground that Kantâs notion of duties to oneself easily captures wrongdoing in absence of harm or wrong to others. Then, I draw specifically on Kantâs âduties to oneself as an animal beingâ to introduce a duty of self-government. This duty is based on the negative causal impact of the activities it regulates on a human beingâs mental and physical powers, and, ultimately, on the moral employment of these powers. After doing so, I argue that the duty against screen overexposure is an instance of the duty of self-government. Finally, I consider some objections.Publisher PDFPeer reviewe
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A genetic algorithm for the design of a fuzzy controller for active queue management
Active queue management (AQM) policies are those
policies of router queue management that allow for the detection of network congestion, the notification of such occurrences to the
hosts on the network borders, and the adoption of a suitable control
policy. This paper proposes the adoption of a fuzzy proportional
integral (FPI) controller as an active queue manager for Internet
routers. The analytical design of the proposed FPI controller is
carried out in analogy with a proportional integral (PI) controller,
which recently has been proposed for AQM. A genetic algorithm is
proposed for tuning of the FPI controller parameters with respect
to optimal disturbance rejection. In the paper the FPI controller
design metodology is described and the results of the comparison
with random early detection (RED), tail drop, and PI controller
are presented
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A management architecture for active networks
In this paper we present an architecture for network and applications management, which is based on the Active Networks paradigm and shows the advantages of network programmability. The stimulus to develop this architecture arises from an actual need to manage a cluster of active nodes, where it is often required to redeploy network assets and modify nodes connectivity. In our architecture, a remote front-end of the managing entity allows the operator to design new network topologies, to check the status of the nodes and to configure them. Moreover, the proposed framework allows to explore an active network, to monitor the active applications, to query each node and to install programmable traps. In order to take advantage of the Active Networks technology, we introduce active SNMP-like MIBs and agents, which are dynamic and programmable. The programmable management agents make tracing distributed applications a feasible task. We propose a general framework that can inter-operate with any active execution environment. In this framework, both the manager and the monitor front-ends communicate with an active node (the Active Network Access Point) through the XML language. A gateway service performs the translation of the queries from XML to an active packet language and injects the code in the network. We demonstrate the implementation of an active network gateway for PLAN (Packet Language for Active Networks) in a forty active nodes testbed. Finally, we discuss an application of the active management architecture to detect the causes of network failures by tracing network events in time
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Adaptive routing in active networks
New conceptual ideas on network architectures have been proposed in the recent past. Current store-andforward
routers are replaced by active intermediate systems,
which are able to perform computations on transient packets,
in a way that results very helpful for developing and
deploying new protocols in a short time. This paper introduces a new routing algorithm, based on a congestion
metric, and inspired by the behavior of ants in nature. The
use of the Active Networks paradigm associated with a cooperative learning environment produces a robust, decentralized algorithm capable of adapting quickly to changing conditions
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