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Search Results: 1 - 10 of 3254 matches for " Johan Lukkien "
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A Generic Service Architecture for Secure Ubiquitous Computing Systems  [PDF]
Shudong Chen, Johan Lukkien, Richard Verhoeven
Int'l J. of Communications, Network and System Sciences (IJCNS) , 2012, DOI: 10.4236/ijcns.2012.51007
Abstract: The development of ubiquitous computing systems benefits tremendously from the service-oriented computing concept in seamless interoperation of heterogeneous devices. However, architectures, services interfaces and network implementation of the existing service-oriented systems differ case by case. Furthermore, many systems lack the capability of being applied to resource constrained devices, for example, sensors. Therefore, we propose a standardized approach to present a service to the network and to access a networked service, which can be adopted by arbitrary types of devices. In this approach, services are specified and exposed through a set of standardized interfaces. Moreover, a virtual community concept is introduced to determine a secure boundary within which services can be freely discovered, accessed and composed into applications; a hierarchical management scheme is presented which enables the third party management of services and their underlying resources. In this way, application control logic goes into the network and environment context is dealt with intelligently by the system. A prototype system is developed to validate our ideas. Results show the feasibility of this open distributed system software architecture.
Relevance As a Metric for Evaluating Machine Learning Algorithms
Aravind Kota Gopalakrishna,Tanir Ozcelebi,Antonio Liotta,Johan J. Lukkien
Computer Science , 2013, DOI: 10.1007/978-3-642-39712-7_15
Abstract: In machine learning, the choice of a learning algorithm that is suitable for the application domain is critical. The performance metric used to compare different algorithms must also reflect the concerns of users in the application domain under consideration. In this work, we propose a novel probability-based performance metric called Relevance Score for evaluating supervised learning algorithms. We evaluate the proposed metric through empirical analysis on a dataset gathered from an intelligent lighting pilot installation. In comparison to the commonly used Classification Accuracy metric, the Relevance Score proves to be more appropriate for a certain class of applications.
Adaptive Broadcast Suppression for Trickle-Based Protocols
Thomas M. M. Meyfroyt,Milosh Stolikj,Johan J. Lukkien
Computer Science , 2015, DOI: 10.1109/WoWMoM.2015.7158134
Abstract: Low-power wireless networks play an important role in the Internet of Things. Typically, these networks consist of a very large number of lossy and low-capacity devices, challenging the current state of the art in protocol design. In this context the Trickle algorithm plays an important role, serving as the basic mechanism for message dissemination in notable protocols such as RPL and MPL. While Trickle's broadcast suppression mechanism has been proven to be efficient, recent work has shown that it is intrinsically unfair in terms of load distribution and that its performance relies strongly on network topology. This can lead to increased end-to-end delays (MPL), or creation of sub-optimal routes (RPL). Furthermore, as highlighted in this work, there is no clear consensus within the research community about what the proper parameter settings of the suppression mechanism should be. We propose an extension to the Trickle algorithm, called adaptive-k, which allows nodes to individually adapt their suppression mechanism to local node density. Supported by analysis and a case study with RPL, we show that this extension allows for an easier configuration of Trickle, making it more robust to network topology.
Proactive Dependability Framework for Smart Environment Applications
Ehsan Ullah Warriach,Tanir Ozcelebi,Johan J. Lukkien
Computer Science , 2015,
Abstract: Smart environment applications demand novel solutions for managing quality of services, especially availability and reliability at run-time. The underlying systems are changing dynamically due to addition and removal of system components, changing execution environments, and resources depletion. Therefore, in such dynamic systems, the functionality and the performance of smart environment applications can be hampered by faults. In this paper, we follow a proactive approach to anticipate system state at runtime. We present a proactive dependability framework to prevent faults at runtime based on predictive analysis to increase availability and reliability of smart environment applications, and reduce manual user interventions.
Improving the Performance of Trickle-Based Data Dissemination in Low-Power Networks
Milosh Stolikj,Thomas M. M. Meyfroyt,Pieter J. L. Cuijpers,Johan J. Lukkien
Computer Science , 2015, DOI: 10.1007/978-3-319-15582-1_12
Abstract: Trickle is a polite gossip algorithm for managing communication traffic. It is of particular interest in low-power wireless networks for reducing the amount of control traffic, as in routing protocols (RPL), or reducing network congestion, as in multicast protocols (MPL). Trickle is used at the network or application level, and relies on up-to-date information on the activity of neighbors. This makes it vulnerable to interference from the media access control layer, which we explore in this paper. We present several scenarios how the MAC layer in low-power radios violates Trickle timing. As a case study, we analyze the impact of CSMA/CA with ContikiMAC on Trickle's performance. Additionally, we propose a solution called Cleansing that resolves these issues.
Properties of Lorenz Curves for Transformed Income Distributions  [PDF]
Johan Fellman
Theoretical Economics Letters (TEL) , 2012, DOI: 10.4236/tel.2012.25091
Abstract: Redistributions of income can be considered as variable transformations of the initial income variable. The transformation is usually assumed to be positive, monotone-increasing and continuous, but discontinuous transformations have also been discussed recently. If the transformation is a tax or a transfer policy, the transformed variable is either the post-tax or the post-transfer income. A central problem has been the Lorenz dominance between the initial and the transformed income. This study considers analyses of other properties of the transformed Lorenz curves, especially its limits. We take in account mainly two cases (a) the transformed variable Lorenz dominates the initial one and (b) the initial Lorenz dominates the transformed one. For applications, the first case is more important than the second. The limits obtained are not accurate for a specific transformation, but do hold generally for all distributions and a broad class of transformations so that, if one pursues general conditions the inequalities obtained cannot be improved.
Properties of Non-Differentiable Tax Policies  [PDF]
Johan Fellman
Theoretical Economics Letters (TEL) , 2013, DOI: 10.4236/tel.2013.33022

In this study, we reconsider the effect of variable transformations on the redistribution of income. We assume that the density function is continuous. If the theorems should hold for all income distributions, the conditions earlier given are both necessary and sufficient. Different conditions are compared. One main result is that continuity is a necessary condition if one demands that the income inequality should remain or be reduced. In our previous studies, of tax policies the assumption was that the transformations were differentiable and satisfy a derivative condition. In this study, we show that it is possible to reduce this assumption to a continuity condition.

Educational Activities at the Sami Folk High School 1942-1982  [PDF]
Johan Hansson
Creative Education (CE) , 2015, DOI: 10.4236/ce.2015.69090
Abstract: The Sami folk high school started in 1942 as a school for young Sami that needed more education that the Swedish folk school or nomadic school offered its pupils. The school was managed by the Swedish mission society, an organization within the Swedish church. The school was successful but struggled with financial problems. The result was that a foundation with Sami representation managed the school instead after 1972. The following year was even more successful. The number of students increased, and the management could offer more courses and their curriculum had more Sami elements than earlier. However, there was also some conflicts during the 1970s. The largest one being the language boycott addressing the issue of Sami languages at the Sami folk high school as a subject in the school, and as an important part of the Sami culture and identity. This article describes the education of the Sami folk high school’s first 40 years with the help of a model for Sami pedagogy developed by Keskitalo and Määttä. The model shows that the education is to a large extent affected by outer factors—self determination, as well as inner factors—language issues and the curriculum.
Transfer Policies with Discontinuous Lorenz Curves  [PDF]
Johan Fellman
Journal of Mathematical Finance (JMF) , 2016, DOI: 10.4236/jmf.2016.61003

In earlier papers, classes of transfer policies have been studied and maximal and minimal Lorenz curves \"\"??obtained. In addition, there are policies belonging to the class with given Gini indices or passing through given points in the \"\"?plane. In general, a transformation \"\"?describing a realistic transfer policy has to be continuous. In this paper the results are generalized and the class of transfer policies?\"\"?is modified so that the members may be discontinuous. If there is an optimal policy which Lorenz dominates all policies in the class, it must be continuous. The necessary and sufficient conditions under which a given differentiable Lorenz curve \"\"?can be generated by a member of a given class of transfer policies are obtained. These conditions are equivalent to the condition that the transformed variable \"\"?stochastically dominates the initial variable X. The theory presented is obviously applicable in connection with other income redistributive studies such that the discontinuity can be assumed. If the problem is reductions in taxation, then the reduction for a taxpayer can be considered as a new benefit. The class of transfer policies can also be used for comparisons between different transfer-raising situations.

Transformations and Lorenz Curves: Sufficient and Necessary Conditions  [PDF]
Johan Fellman
Theoretical Economics Letters (TEL) , 2016, DOI: 10.4236/tel.2016.63050
Abstract: In this study, we reconsider the effect of variable transformations on income inequality. Under the assumption that the theorems should hold for all income distributions, earlier given sufficient conditions are also necessary. Different versions of the conditions are compared. Furthermore, one can prove that the assumption of continuity of the transformations can be implicitly included in the necessary and sufficient conditions, and hence, it can be dropped from the assumptions. The effects of two transformations on income inequality are compared.
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