Cognitive Medium Access: Exploration, Exploitation and Competition

This paper establishes the equivalence between cognitive medium access and the competitive multi-armed bandit problem. First, the scenario in which a single cognitive user wishes to opportunistically exploit the availability of empty frequency bands in the spectrum with multiple bands is considered. In this scenario, the availability probability of each channel is unknown to the cognitive user a priori. Hence efficient medium access strategies must strike a balance between exploring the availability of other free channels and exploiting the opportunities identified thus far. By adopting a Bayesian approach for this classical bandit problem, the optimal medium access strategy is derived and its underlying recursive structure is illustrated via examples. To avoid the prohibitive computational complexity of the optimal strategy, a low complexity asymptotically optimal strategy is developed. The proposed strategy does not require any prior statistical knowledge about the traffic pattern on the different channels. Next, the multi-cognitive user scenario is considered and low complexity medium access protocols, which strike the optimal balance between exploration and exploitation in such competitive environments, are developed. Finally, this formalism is extended to the case in which each cognitive user is capable of sensing and using multiple channels simultaneously.Comment: Submitted to IEEE/ACM Trans. on Networking, 14 pages, 2 figure

Knowledge Management and Sustainable Agriculture:the Italian Case

The contemporary knowledge-based economy requires global usage of information in all aspects of modern society. Pertinent information is an important asset for successful business, therefore an application of knowledge management in organisational practice has become a crucial factor for the viability and sustainable development of enterprises. This is particularly relevant for the agricultural context, which needs modern practices for enhancement and development. However, information and knowledge, due to their intangible character, seem difficult to manage and organize. Therefore the paper targeted at developing sustainable organizational model of knowledge management for small and medium enterprises. Italian agriculture is considered as a context for this study, and knowledge management was offered as a tool for facilitating agricultural performance and increasing competitiveness of agricultural sector. A wide concept of knowledge management and specified agricultural context require a theory-based approach to research and a survey. Thus, the research methodology includes the next four parts. The first one contains literature review and examines definitions, strategies, approaches and models of sustainable knowledge management. The second part includes content analysis of 105 scientific publications. The third part of methodology is based on the results of the two previous parts and includes creating the model of knowledge management. Verification of this model is the last part of the research. Verification was executed through on-line questionnaire distributed to Italian agricultural enterprises throughout the country on their intentions and awareness towards knowledge management and developed model of knowledge management. The results of the survey have demonstrated farmer’s incentives to implement the developed knowledge management model with flexible approach in its organisation

TARGET: Rapid Capture of Process Knowledge

TARGET (Task Analysis/Rule Generation Tool) represents a new breed of tool that blends graphical process flow modeling capabilities with the function of a top-down reporting facility. Since NASA personnel frequently perform tasks that are primarily procedural in nature, TARGET models mission or task procedures and generates hierarchical reports as part of the process capture and analysis effort. Historically, capturing knowledge has proven to be one of the greatest barriers to the development of intelligent systems. Current practice generally requires lengthy interactions between the expert whose knowledge is to be captured and the knowledge engineer whose responsibility is to acquire and represent the expert's knowledge in a useful form. Although much research has been devoted to the development of methodologies and computer software to aid in the capture and representation of some types of knowledge, procedural knowledge has received relatively little attention. In essence, TARGET is one of the first tools of its kind, commercial or institutional, that is designed to support this type of knowledge capture undertaking. This paper will describe the design and development of TARGET for the acquisition and representation of procedural knowledge. The strategies employed by TARGET to support use by knowledge engineers, subject matter experts, programmers and managers will be discussed. This discussion includes the method by which the tool employs its graphical user interface to generate a task hierarchy report. Next, the approach to generate production rules for incorporation in and development of a CLIPS based expert system will be elaborated. TARGET also permits experts to visually describe procedural tasks as a common medium for knowledge refinement by the expert community and knowledge engineer making knowledge consensus possible. The paper briefly touches on the verification and validation issues facing the CLIPS rule generation aspects of TARGET. A description of efforts to support TARGET's interoperability issues on PCs, Macintoshes and UNIX workstations concludes the paper

Large-x Parton Distributions

Reliable knowledge of parton distributions at large x is crucial for many searches for new physics signals in the next generation of collider experiments. Although these are generally well determined in the small and medium x range, it has been shown that their uncertainty grows rapidly for x>0.1. We examine the status of the gluon and quark distributions in light of new questions that have been raised in the past two years about "large-x" parton distributions, as well as recent measurements which have improved the parton uncertainties. Finally, we provide a status report of the data used in the global analysis, and note some of the open issues where future experiments, including those planned for Jefferson Labs, might contribute.Comment: LaTeX, 9 pages, 7 figures. Invited talk presented at the ``Workshop on Nucleon Structure in the High x-Bjorken Region (HiX2000),'' Temple University, Philadelphia, Pennsylvania, March 30-April 1, 200

Waveform Design for Secure SISO Transmissions and Multicasting

Wireless physical-layer security is an emerging field of research aiming at preventing eavesdropping in an open wireless medium. In this paper, we propose a novel waveform design approach to minimize the likelihood that a message transmitted between trusted single-antenna nodes is intercepted by an eavesdropper. In particular, with knowledge first of the eavesdropper's channel state information (CSI), we find the optimum waveform and transmit energy that minimize the signal-to-interference-plus-noise ratio (SINR) at the output of the eavesdropper's maximum-SINR linear filter, while at the same time provide the intended receiver with a required pre-specified SINR at the output of its own max-SINR filter. Next, if prior knowledge of the eavesdropper's CSI is unavailable, we design a waveform that maximizes the amount of energy available for generating disturbance to eavesdroppers, termed artificial noise (AN), while the SINR of the intended receiver is maintained at the pre-specified level. The extensions of the secure waveform design problem to multiple intended receivers are also investigated and semidefinite relaxation (SDR) -an approximation technique based on convex optimization- is utilized to solve the arising NP-hard design problems. Extensive simulation studies confirm our analytical performance predictions and illustrate the benefits of the designed waveforms on securing single-input single-output (SISO) transmissions and multicasting

Community Empowerment: Training on Cultivation of Mushroom From Corncob’s Waste In Air Terang Village, Central Sulawesi

The community has not utilized the abundant corncob waste in Air Terang Village. Corncob waste can be used as a medium for growing mushrooms. This program service aims to improve the knowledge and skills of the community in Air Terang Village, Tiloan District, Buol Regency in cultivating mushrooms from corncobs. The implementation of this service uses the Participatory Action Research (PAR) method, which consists of three stages: preparation, implementation, and evaluation. The result of this community service program is the community begins to understand and realize the use of corncob waste as a medium for growing mushrooms and can cultivate mushrooms from corncobs. Recommendations for the next service program are mushroom post-harvest processing and training on mushroom marketing strategies.The community has not utilized the abundant corncob waste in Air Terang Village. Corncob waste can be used as a medium for growing mushrooms. This program service aims to improve the knowledge and skills of the community in Air Terang Village, Tiloan District, Buol Regency in cultivating mushrooms from corncobs. The implementation of this service uses the Participatory Action Research (PAR) method, which consists of three stages: preparation, implementation, and evaluation. The result of this community service program is the community begins to understand and realize the use of corncob waste as a medium for growing mushrooms and can cultivate mushrooms from corncobs. Recommendations for the next service program are mushroom post-harvest processing and training on mushroom marketing strategies