Development of numerical methods for the reactive transport of chemical species in a porous media : a nonlinear conjugate gradient method

In the framework of the evaluation of nuclear waste disposal safety, the French Atomic Energy Commission (CEA) is interested in modelling the reactive transport in porous media. At a given time step, the equation system of reactive-transport can be written as a system of nonlinear coupled equations F(x) = 0. In the computational code which is presently used, this system is solved using classical sequential iterative algorithms (SIA). We are currently investigating nonlinear conjugate gradient methods to improve the resolution of the system. Indeed, the handling of the coupling is improved by numerical derivation along the descent direction. The original feature of this method is the use of an explicit formula for the descent parameter. We choose an approach involving two distinct codes, that is one code for the chemistry and one code for the transport equations

Development of numerical methods for the reactive transport of chemical species in a porous media : a nonlinear conjugate gradient method

In the framework of the evaluation of nuclear waste disposal safety, the French Atomic Energy Commission (CEA) is interested in modelling the reactive transport in porous media. At a given time step, the equation system of reactive-transport can be written as a system of nonlinear coupled equations F(x) = 0. In the computational code which is presently used, this system is solved using classical sequential iterative algorithms (SIA). We are currently investigating nonlinear conjugate gradient methods to improve the resolution of the system. Indeed, the handling of the coupling is improved by numerical derivation along the descent direction. The original feature of this method is the use of an explicit formula for the descent parameter. We choose an approach involving two distinct codes, that is one code for the chemistry and one code for the transport equations

Coupling Methodology within the Software Platform Alliances

CEA, ANDRA and EDF are jointly developing the software platform ALLIANCES which aim is to produce a tool for the simulation of nuclear waste storage and disposal repository. This type of simulations deals with highly coupled thermo-hydro-mechanical and chemical (T-H-M-C) processes. A key objective of Alliances is to give the capability for coupling algorithms development between existing codes. The aim of this paper is to present coupling methodology use in the context of this software platform.Comment: 7 page

Study of glyceraldehyde-3-phosphate oxidoreductases from archaea and bacteria

Carbon monoxide is a greenhouse gas mainly produced by anthropogenic sources, but the electrons liberated for CO oxidation toCO2 have a very low potential of -520 mV. Interestingly, CO can be produced in the syngas by the gasification of renewable sources. Hence, to exploit these low potential electrons and carbon from renewable sources, the general objective of this project was to engineer Escherichia coli to use carbon monoxide as the sole energy and carbon source. One of the engineering points was the heterologous expression in E. coli of the glyceraldehyde-3-phosphate oxidoreductase (GAPOR) to function in the gluconeogenic direction to fix the low potential electrons from the carbon monoxide. The already characterised GAPOR from the mesophilic Methanococcus maripaludis has been produced in a mutant E. coli strain optimised for crude extract enzyme assay. Three genes were deleted from the E. coli Rosetta-gami 2(DE3): iscR to improve the availability of the [4Fe-4S] cofactor in the cell; selA and hypF to diminish the benzyl viologen reduction background activity observed in the preliminary test. The glyceraldehyde-3-phosphate (G3P) oxidation activity of GAPOR in cell crude extract and affinity purified has been tested, but no activity was observed. In parallel, the enzymes from the M. maripaludis molybdenum cofactor biosynthesis pathway were co-expressed with GAPOR to improve the G3P-dependent activity. However, no enzymatic activity has been detected. A new LC-MS method of molybdopterin cofactor identification has been used to detect the cofactor, but so far, no cofactor was observed in the protein extract. The expression of the newly discovered bacterial homologous genes of GAPOR: GOR-SL from the mesophilic bacterium Geosporobacter ferrireducens, was tentatively expressed in E. coli, but no soluble enzyme has been detected. The expression of both proteins was tested in aldehyde ferredoxin oxidoreductase expressing bacteria Clostridium autoethanogenum and Clostridium acetobutylicum under the control of different inducible and constitutive promoters. GAPOR and GOR expression has been observed in the soluble fraction of C. acetobutylicum. NoG3P-dependent activity has been detected during the enzyme assay on the purified enzyme and no impact on the cell solvent production in batch culture was either seen. This study did not allow the production of active enzymes; nevertheless, it opened a new path of research in the archaeal molybdenum cofactor biosynthesis pathway and the pursuit of the investigation in GAPOR and GOR-SL-like protein in C. acetobutylicum

Introduction to the digital government and Business Process Management (BPM) minitrack HICSS'54

Digital Government (traditionally known as e- Government) focuses on value delivery to citizens through information and communication technology (ICT) support for processes, activities and resources. Digital government’s collaborative processes involve organizations (employees, technologies), partners (providers, consumers), and users (citizens, foreigners), leading to complex interactions within different e- Government models and available technologies. Business Process Management (BPM) constitutes a real asset for enhancing the services of an organization and their coordination, as well as the products that each actor of a virtual network delivers to meet clients’ expectations (citizens, patients, etc.). Successful interorganizational process management within e- Government collaborative organizations will lead to better conceptual and technological integration, not only with each other but also with citizens and users in general. To this end, it is necessary to devise new ways to deal with the complexity of e-Government collaborative process definition, modeling, analysis, enactment and monitoring from various dimensions and points of view including theory, engineering, interoperability, agility, social aspects, etc

Towards a Metamodel supporting E-government Collaborative Business Processes Management within a Service-based Interoperability Platform

Interoperability between different organizations is a complex task, where a key element is to be able to define without ambiguity the concepts that are involved in each domain and their relations. A key aspect for enabling e-government is the technological support for complex interaction scenarios, defining collaborative Business Processes (BPs) that are the basis for these interactions. E-government collaborative BPs involve several and heterogeneous participants: organizations, partners, and users, with different capabilities, needs, and available technical support. The goal of this paper is to present ongoing research on e-government cross-organizational collaborative BPs support in a service-based interoperability platform. This proposal is focused on the formalization and exploitation of e-government knowledge and information (i.e., metamodels and ontologies) to improve the definition, automated generation, control, monitoring and improvement of e-government collaborative BPs

Study of glyceraldehyde-3-phosphate oxidoreductases from archaea and bacteria

Carbon monoxide is a greenhouse gas mainly produced by anthropogenic sources, but the electrons liberated for CO oxidation toCO2 have a very low potential of -520 mV. Interestingly, CO can be produced in the syngas by the gasification of renewable sources. Hence, to exploit these low potential electrons and carbon from renewable sources, the general objective of this project was to engineer Escherichia coli to use carbon monoxide as the sole energy and carbon source. One of the engineering points was the heterologous expression in E. coli of the glyceraldehyde-3-phosphate oxidoreductase (GAPOR) to function in the gluconeogenic direction to fix the low potential electrons from the carbon monoxide. The already characterised GAPOR from the mesophilic Methanococcus maripaludis has been produced in a mutant E. coli strain optimised for crude extract enzyme assay. Three genes were deleted from the E. coli Rosetta-gami 2(DE3): iscR to improve the availability of the [4Fe-4S] cofactor in the cell; selA and hypF to diminish the benzyl viologen reduction background activity observed in the preliminary test. The glyceraldehyde-3-phosphate (G3P) oxidation activity of GAPOR in cell crude extract and affinity purified has been tested, but no activity was observed. In parallel, the enzymes from the M. maripaludis molybdenum cofactor biosynthesis pathway were co-expressed with GAPOR to improve the G3P-dependent activity. However, no enzymatic activity has been detected. A new LC-MS method of molybdopterin cofactor identification has been used to detect the cofactor, but so far, no cofactor was observed in the protein extract. The expression of the newly discovered bacterial homologous genes of GAPOR: GOR-SL from the mesophilic bacterium Geosporobacter ferrireducens, was tentatively expressed in E. coli, but no soluble enzyme has been detected. The expression of both proteins was tested in aldehyde ferredoxin oxidoreductase expressing bacteria Clostridium autoethanogenum and Clostridium acetobutylicum under the control of different inducible and constitutive promoters. GAPOR and GOR expression has been observed in the soluble fraction of C. acetobutylicum. NoG3P-dependent activity has been detected during the enzyme assay on the purified enzyme and no impact on the cell solvent production in batch culture was either seen. This study did not allow the production of active enzymes; nevertheless, it opened a new path of research in the archaeal molybdenum cofactor biosynthesis pathway and the pursuit of the investigation in GAPOR and GOR-SL-like protein in C. acetobutylicum

Expanding Awareness: Comparing Location, Keyword, and Network Filtering Methods to Collect Hyperlocal Social Media Data

Opportunities to collect real-time social media data during a crisis remain limited to location and keyword filtering despite the sparsity of geographic metadata and the tendency of keyword-based methods to capture information posted by remote rather than local users. Here we introduce a third, network filtering method that uses social network ties to infer the location of social media users in a geographic community and collect data from networks of these users during a crisis. In this paper we compare all three methods by analyzing the distribution of situational reports of infrastructure damage and service disruption across location, keyword, and network-filtered social media data during a weather emergency. We find that network filtering doubles the number of situational reports collected in real-time compared to location and keyword filtering alone, but that all three methods collect unique reports that can support situational awareness of incidents occurring across a community