Abstract:There is growing interest in evaluating the impacts at the watershed scale of agricultural best management practices (BMPs) designed to improve water quality. Many approaches to impact assessment require detailed information about actual BMP use by farmers and landowners in a watershed. This paper examines the strengths and weaknesses of using formal USDA Natural Resources Conservation Service records of conservation program participation as an indicator of spatial and temporal patterns of BMP implementation and maintenance. Field interviews with conservation program participants revealed potential limitations with official records regarding (1) documentation of the incidence of successful BMP implementation, (2) the nature of the BMPs that were implemented, (3) accurate measurement of the timing and location of BMP implementations, and (4) information about the long-term use and maintenance of implemented BMPs. The results suggest that official records should be field-verified before being used as indicators of BMP use. The findings also point to a larger need for development of more robust and accurate systems for tracking BMP implementation and maintenance over periods of time. Key words: best management practice (BMP) implementation-maintenance-measurement-official records-watershedThere is growing interest among policymakers, farmers, and researchers in documenting the impacts of conservation practice adoption on environmental outcomes (Helmers et al. 2007;James and Cox 2008;Mausbach and Dedrick 2004;Van Liew et al. 2007). Numerous approaches to measuring the impacts of best management practices (BMPs) on water quality have been used, ranging from controlled experiments on small research plots or individual farm fields, monitoring of paired watersheds, empirical models that derive output coefficients for broad classes of land use, and process models that simulate the dynamics of watershed physical and hydrologic processes (Cherry et al. 2008). National-level estimates of the impacts of conservation programs have also been developed based on estimates of BMP adoption from large-scale representative sample surveys of farmers (Lambert et al. 2007; USDA NRCS 2009a, 2009b.Efforts to quantify the impacts of realworld agricultural BMPs on water quality at the watershed scale can benefit from the availability of accurate information about the current and past conservation behaviors of farmers and landowners. However, methods for gathering data on conservation behaviors and actual BMP use within watersheds vary widely, and strategies to integrate this information with detailed biophysical monitoring data in analytical models are still in their infancy. One recent initiative designed to address this situation is the USDA Conservation Effects Assessment Program (CEAP) that has coordinated the efforts of 14 existing USDA Agricultural Research Service (ARS) watershed research sites and allocated almost $8 million between 2004 to 2007 to fund another 13 non-ARS watershedscale research projects to develop innovat...

Internet growth has generated new types of services where the use of sensors and actuators is especially remarkable. These services compose what is known as the Internet of Things (IoT). One of the biggest current challenges is obtaining a safe and easy access control scheme for the data managed in these services. We propose integrating IoT devices in an access control system designed for Web-based services by modelling certain IoT communication elements as resources. This would allow us to obtain a unified access control scheme between heterogeneous devices (IoT devices, Internet-based services, etc.). To achieve this, we have analysed the most relevant communication protocols for these kinds of environments and then we have proposed a methodology which allows the modelling of communication actions as resources. Then, we can protect these resources using access control mechanisms. The validation of our proposal has been carried out by selecting a communication protocol based on message exchange, specifically Message Queuing Telemetry Transport (MQTT). As an access control scheme, we have selected User-Managed Access (UMA), an existing Open Authorization (OAuth) 2.0 profile originally developed for the protection of Internet services. We have performed tests focused on validating the proposed solution in terms of the correctness of the access control system. Finally, we have evaluated the energy consumption overhead when using our proposal.

We introduce and explore a family of vertex-coloring problems which, surprisingly enough, have not been considered before despite stemming from the problem of Wi-Fi channel assignment. Given a spectrum of colors, endowed with a matrix of interferences between each pair of colors, the Threshold Spectrum Coloring problem fixes the number of colors available and aims to minimize the interference threshold, i.e., the maximum of the interferences at the vertices. Conversely, the Chromatic Spectrum Coloring problem fixes a threshold and aims to minimize the number of colors for which respecting that threshold is possible. As main theoretical results, we prove tight upper bounds for the solutions to each problem. Since both problems turn out to be NP-hard, we complete the scene with experimental results. We propose a DSATUR-based heuristic and study its performance to minimize the maximum vertex interference in Wi-Fi channel assignment, both for randomly generated graphs and for a real-world scenario. Further, for all these graphs we experimentally check the goodness of the theoretical bounds.

Due to the low cost of CMOS IP-based cameras, wireless surveillance sensor networks have emerged as a new application of sensor networks able to monitor public or private areas or even country borders. Since these networks are bandwidth intensive and the radioelectric spectrum is limited, especially in unlicensed bands, it is mandatory to assign frequency channels in a smart manner. In this work, we propose the application of automated negotiation techniques for frequency assignment. Results show that these techniques are very suitable for the problem, being able to obtain the best solutions among the techniques with which we have compared them.

Abstract-The rise of the Internet of Things (IoT) paradigm has allowed the design and development of new services interconnecting heterogeneous devices. However, the complexity of these new systems hasn't been followed by the increase of intelligence and reasoning of the devices connected. On the other hand, intelligent agent systems have developed precisely these characteristics so the combination of both paradigms by modelling intelligent agents in IoT devices is a very promising approach that will enable a more powerful and smart IoT. The interconnection of agents through a Internet-based network implies addressing critical issues that affect all network communications, such as security, privacy and access control, specially given the sensitivity of the information exchanged by agents. In this paper, we propose the application of User-Managed Access (UMA) to provide an unified access control schema for an heterogeneous hybrid architecture of IoT devices and intelligent agents.