Information criteria determine the number of active sources

With the neuroelectromagnetic inverse problem, the optimal choice of the number of sources is a difficult problem, especially in the presence of correlated noise. In this paper we present a number of information criteria that help to solve this problem. They are based on the probability density function of the measurements or their eigenvalues. Make use of the Akaike or MDL (minimum description length) correction term and all employ some sort of noise information. By extensive simulations we investigated the conditions under which these criteria yield reliable estimations. We were able to quantify two major factors of influence: (1) the precision of the noise information and (2) the signal-to-noise ratio (SNR). Here defined as the ratio of the smallest signal eigenvalues and the average of the noise eigenvalues. Furthermore, we found that the Akaike correction term tends to overestimate, due to its greater sensibility to the precision of the noise informatio

Overview Of Coupling Of Data, Models And Information Through The Web Using Existing Standards

Assessment of environmental status and integral safety requires combination of information from many sources, coming from either databases or increasingly via live model (scenario) simulations. Many of these models require input from one another, sometimes unidirectional, but more and more two-directional as well. Many protocols and frameworks are available for model coupling, often based on open standards and implementations. Previous overviews of coupling protocols have focused on data exchange volume, data complexity, invasiveness into existing models and support for specific programming languages. We extend the overview using recent developments in web-based protocols and focus on the suitability for internet-based data exchange. We also extend the focus of previous reviews by also taking the coupling with aggregated information products for end-users into account. We propose a hierarchical ordering of all standards for specific types of end-users

DRIHM - An Infrastructure To Advance Hydro-Meteorological Research

One of the main challenges in hydro-meteorological research (HMR) is predicting the impact of weather and climate changes on the environment, society and economy, including local severe hazards such as floods and landslides. At the heart of this challenge lies the ability to have easy access to hydro-meteorological data and models, and facilitate the collaboration across discipline boundaries. Within the DRIHM project (Distributed Research Infrastructure for Hydro-Meteorology, www.drihm.eu, EC funded FP7 project 2011-2015) we develop a prototype e-Science environment to facilitate this collaboration and provide end-to-end HMR services (models, datasets, and post-processing tools) at the European level, with the ability to expand to global scale. The objectives of DRIHM are to lead the definition of a common long-term strategy, to foster the development of new HMR models, workflows and observational archives for the study of severe hydro-meteorological events, to promote the execution and analysis of high-end simulations, and to support the dissemination of predictive models as decision analysis tools. For this we implement a service portal to construct heterogeneous simulation workflows that can include deterministic and ensemble runs on a heterogeneous infrastructure consisting of HPC, grid and Windows cloud resources. Via another FP7 project called DRIHM2US (www.drihm2us.eu) we collaborate with the NSF funded SCIHM project (www.scihm.org) to build a wider international collaborative network. This contribution will provide a sketch of the DRIHM architecture and show some use cases such as the November 2011 Genoa flooding

The role of gate operation in reducing problems with cohesive and non-cohesive sediments in irrigation canals

Sediments cause serious problems in irrigation systems, adversely affecting canal performance, driving up maintenance costs and, in extreme cases, threatening system sustainability. Multiple studies were done on the deposition of non-cohesive sediment and implications for canal design, the use of canal operation in handling sedimentation problems is relatively under-studied, particularly for cohesive sediments. In this manuscript, several scenarios regarding weirs and gate operation were tested, using the Delft3D model, applied to a case study from the Gezira scheme in Sudan. Findings show that weirs play a modest role in sedimentation patterns, where their location influences their effectiveness. On the contrary, gate operation plays a significant role in sedimentation patterns. Reduced gate openings may cause canal blockage while intermittently fully opening and closing of gates can reduce sediment deposition in the canal by 54% even under conditions of heavy sediment load. Proper location of weirs and proper adjusting of the branch canal's gate can substantially reduce sedimentation problems while ensuring sufficient water delivery to crops. The use of 2D/3D models provides useful insights into spatial and temporal patterns of deposition and erosion but has challenges related to running time imposing a rather coarse modelling resolution to keep running times acceptable.</p