Optimization of Source/Relay Wireless Networks with Multiuser Nodes

We analyze the achievable data rate of cooperative relaying strategies in networks where nodes operate in half-duplex mode. Nodes have to deliver their data to a gateway, at a certain rate, and may have limited energy capabilities, as in the case of energy-harvesting communication networks. Both the requested data rate and the available energy capabilities may vary from node to node. Under such constraints, we take an information-theoretic approach and derive cut-set upper bounds to the achievable rate. Furthermore, we devise two kinds of communication strategies, each aiming at a different objective. The former ensures a fair rate allocation to the network nodes, but it neglects their energy constraints. The latter does consider energy constraints by meeting the requirements on the average power consumption at each node and by providing fairness in the data rate allocation. We show the performance of the aforementioned communication strategies, highlighting their effectiveness and providing useful insights on the system behavior

The Importance of Worker Reputation Information in Microtask-Based Crowd Work Systems

This paper presents the first systematic investigation of the potential performance gains for crowd work systems, deriving from available information at the requester about individual worker reputation. In particular, we first formalize the optimal task assignment problem when workers’ reputation estimates are available, as the maximization of a monotone (sub-modular) function subject to Matroid constraints. Then, being the optimal problem NP-hard, we propose a simple but efficient greedy heuristic task allocation algorithm. We also propose a simple “maximum a-posteriori” decision rule and a decision algorithm based on message passing. Finally, we test and compare different solutions, showing that system performance can greatly benefit from information about workers’ reputation. Our main findings are that: i) even largely inaccurate estimates of workers’ reputation can be effectively exploited in the task assignment to greatly improve system performance; ii) the performance of the maximum a-posteriori decision rule quickly degrades as worker reputation estimates become inaccurate; iii) when workers’ reputation estimates are significantly inaccurate, the best performance can be obtained by combining our proposed task assignment algorithm with the message-passing decision algorithm

On chip interconnects for multiprocessor turbo decoding architectures

International audienc

The marketing of herd health and production management services on Dutch dairy farms: perceptions of dairy farmers and their veterinary surgeons

A questionnaire-based survey on veterinary herd health and production management services was conducted on 194 specialist dairy veterinarians and 466 dairy farmers. The farmers were randomly selected from greater than 6,000 farmer clients of the surveyed veterinarians. This paper reports these survey findings and the findings of an earlier survey conducted among the veterinarians. The survey included questions on the attributes of the service itself, the practitioners delivering the service, reasons for participation and the expected future of herd health and production management services. Reasons farmers participated in herd health and production management programmes included; access to routine screening of their herd; increasing profits; and receiving regular veterinary advice or solutions to remedy existing problems. Advantages of participation named included: good management support; higher profits; structural solutions to problems; and being better informed. Differences between farming styles were observed, pointing to the different needs and goals of farming styles. Farmers cited high costs and the time investment required as major disadvantages. The proportion of farmers citing these reasons was lower than expected by the veterinarians. In the future, preventive healthcare will be the main reason of farmers to participate. Farmers who are not using the service can potentially be encouraged to engage the services after gaining increased insight into the herd health and management service structure, the planning of activities, the cost-benefit of the service, veterinary surgeons being more co-operative with other farm advisors and veterinarians being more willing to pay attention to quality issues on the dairy farm