Porous Structure Reconstruction Using Convolutional Neural Networks

The three-dimensional high-resolution imaging of rock samples is the basis for pore-scale characterization of reservoirs. Micro X-ray computed tomography (µ-CT) is considered the most direct means of obtaining the three-dimensional inner structure of porous media without deconstruction. The micrometer resolution of µ-CT, however, limits its application in the detection of small structures such as nanochannels, which are critical for fluid transportation. An effective strategy for solving this problem is applying numerical reconstruction methods to improve the resolution of the µ-CT images. In this paper, a convolutional neural network reconstruction method is introduced to reconstruct high-resolution porous structures based on low-resolution µ-CT images and high-resolution scanning electron microscope (SEM) images. The proposed method involves four steps. First, a three-dimensional low-resolution tomographic image of a rock sample is obtained by µ-CT scanning. Next, one or more sections in the rock sample are selected for scanning by SEM to obtain high-resolution two-dimensional images. The high-resolution segmented SEM images and their corresponding low-resolution µ-CT slices are then applied to train a convolutional neural network (CNN) model. Finally, the trained CNN model is used to reconstruct the entire low-resolution three-dimensional µ-CT image. Because the SEM images are segmented and have a higher resolution than the µ-CT image, this algorithm integrates the super-resolution and segmentation processes. The input data are low-resolution µ-CT images, and the output data are high-resolution segmented porous structures. The experimental results show that the proposed method can achieve state-of-the-art performance.     

Participatory Vulnerability Reduction (PVR): an urban community-based approach for earthquake management

Participation of local people during any disaster is enormous. They possess better knowledge and information about their own community than anyone else from the outside. This study proposes Participatory Vulnerability Reduction (PVR), a community-based approach for disaster management. The concept of PVR was applied to an urban community of Dhaka city (Ward no. 06 of Dhaka North City Corporation) which has been identified by the Comprehensive Disaster Management Programme as one of the most vulnerable areas of the city for earthquake. PVR consists three steps, and in each step, different participatory urban appraisal tools were used. In the first step, the community people assessed the earthquake vulnerability. It was found that some certain parts of the study area are highly vulnerable due to lack of accessibility to the critical facilities, inadequacy of open space, poor construction practice and unsuitable soil condition for building construction. This was followed by analyzing the root causes and effects of these problems. Structural fragility of the buildings, construction of settlements by filling the low-lying areas and development of slums beside taller buildings are the three major causes behind the above vulnerable issues. In the second step, capacity of the community was assessed in terms of resources and their organizational structure. In the final step, local people developed the strategies to overcome the vulnerability and a community-based organizational set up was proposed to coordinate the collective actions. Although developed in local context, application of PVR is not limited for earthquake and it can be replicated for other communities as well.     

Indices based assessment of built-up density and urban expansion of fast growing Surat city using multi-temporal Landsat data sets

GeoJournal - The population growth in urban areas leads to the expansion of built-up area which leads to a number of serious problems like environmental pollution, destruction of urban ecology,...     

Multiple-tracers-aided surface-subsurface hydrological modeling for detailed characterization of regional catchment water dynamics in Kumamoto area,southern Japan

Hydrogeology Journal - Integrated watershed modeling techniques have been applied in recent years to examine surface and subsurface interactions. Model performance is often evaluated by best fit of...     

Transforming local natural resource conflicts to cooperation in a changing climate: Bangladesh and Nepal lessons

ABSTRACT

Since the 1990s, climate change impact discourse has highlighted potential for large scale violent conflicts. However, the role of climate stresses on local conflicts over natural resources, the role of policies and adaptation in these conflicts, and opportunities to enhance cooperation have been neglected. These gaps are addressed in this paper using evidence from participatory action research on 79 cases of local collective action over natural resources that experience conflicts in Bangladesh and Nepal. Climate trends and stresses contributed to just under half of these conflict cases. Nine factors that enable greater cooperation and transformation of conflict are identified. Participatory dialogue and negotiation processes, while not sufficient, changed understanding, attitudes and positions of actors. Many of the communities innovated physical measures to overcome natural resource constraints, underlying conflict, and/or institutional reforms. These changes were informed by improving understanding of resource limitations and indigenous knowledge. Learning networks among community organizations encouraged collective action by sharing successes and creating peer pressure. Incentives for cooperation were important. For example, when community organizations formally permitted excluded traditional resource users to access resources, those actors complied with rules and paid towards management costs. However, elites were able to use policy gaps to capture resources with changed characteristics due to climate change. In most of the cases where conflict persisted, power, policy and institutional barriers prevented community-based organizations from taking up potential adaptations and innovations. Policy frameworks recognizing collective action and supporting flexible innovation in governance and adaptation would enable wider transformation of natural resource conflicts into cooperation.

Key policy insights

• Climate stresses, policy gaps and interventions can all worsen local natural resource conflicts.

• Sectoral knowledge and technical approaches to adaptation are open to elite capture and can foster conflicts.

• Many local natural resource conflicts can be resolved but this requires an enabling environment for participatory dialogue, external facilitation, flexible responses to context, and recognition of disadvantaged stakeholder interests.

• Transforming conflict to greater cooperation mostly involves social and institutional changes, so adaptation policies should focus less on physical works and more on enabling factors such as negotiation, local institutions, knowledge, and incentives.

     

An evaluation of force-based design vs. direct displacement-based design of jointed precast post-tensioned wall systems

The unique features of jointed post-tensioned wall systems, which include minimum structural damage and re-centering capability when subjected to earthquake lateral loads, are the result of using unbonded post-tensioning to attach the walls to the foundation, along with employing energy dissipating shear connectors between the walls. Using acceptance criteria defined in terms of inter-story drift, residual drift, and floor acceleration, this study presents a multiplelevel performance-based seismic evaluation of two five-story unbonded post-tensioned jointed precast wall systems. The design and analysis of these two wall systems, established as the direct displacement-based and force-based solutions for a prototype building used in the PREcast Seismic Structural Systems （PRESSS） program, were performed at 60% scale so that the analysis model could be validated using the PRESSS test data. Both buildings satisfied the performance criteria at four levels of earthquake motions although the design base shear of the direct displacement-based jointed wall system was 50% of that demanded by the force-based design method. The study also investigated the feasibility of controlling the maximum transient inter-story drift in a jointed wall system by increasing the number of energy dissipating shear connectors between the walls but without significantly affecting its re-centering capability.     

Irrigation and farm water management in Pakistan

Present irrigation practices and water management techniques in Pakistan are the result of a long process. Through a cultural-historical approach, generic relationships of some present patterns are traced to their origin. The origin of irrigation was probably in small alluvial valleys of Southwest Asia, which is also considered the hearth of seed agriculture. From a simple beginning the irrigation and water management systems have become extremely complicated to support Pakistan's largest irrigation network in the world.Part of the research for this paper was done at the Department of Geography, South Asia Institute, University of Heidelberg, Heidelberg, Germany during the summer of 1992.     

Korrelation der Sporenzonen der Oberen Trias und des Jura im Mittleren Orient und in Süddeutschland

Zusammenfassung Bei der sporenstratigraphischen Gliederung des mittleren Mesozoikums im Mittleren Orient konnten vom Nor bis zur Unteren Kreide 6 Sporenzonen unterschieden werden: Unterkreide:Ischyosporites variegatus — Rouseisporites laciniatus — Cicatricosisporites-Zone Malm:Ischyosporites variegatus — Rouseisporites laciniatus-Zone Dogger:Ischyosporites variegatus — Duplexisporites problematicus-Zone Lias:Concavisporites — Duplexisporites problematicus-Zone Rät:Concavisporites — Duplexisporites problematicus — Lophotriletes sangburensis — Ricciisporites tuberculatus-Zone Nor:Concavisporites — Duplexisporites problematicus — Lophotriletes sangburensis — Cyclotriletes oligogranifer-ZoneVergleichende Untersuchungen ergaben, daß diese Sporenzonen auch auf Süddeutschland übertragbar sind und den faunistischen Grenzen entsprechen. Nur die sporenstratigraphische Festlegung der Nor/Rätsowie der Dogger/Malm- und der Malm/Unterkreide-Grenze bedürfen noch der Verifizierung.

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In the middle Mesozoic of the Middle East 6 spore-assoziations could be distinguished from the Norian to the Lower Cretaceous: Lower Cretaceous:Ischyosporites variegatus — Rouseisporites laciniatus — Cicatricosisporites zone Upper Jurassic:Ischyosporites variegatus — Rouseisporites laciniatus zone Middle Jurassic:Ischyosporites variegatus — Duplexisporites problematicus zone Lower Jurassic:Concavisporites — Duplexisporites problematicus zone Rhaetian:Concavisporites — Duplexisporites problematicus — Lophotriletes sangburensis — Ricciisporites tuberculatus zone Norian:Concavisporites — Duplexisporites problematicus — Lophotriletes sangburensis — Cyclotriletes oligogranifer zone.The interregional validity and the correspondance of these spore zones with the faunistic boundaries could be substantiated in equivalent sequences in Southern Germany. However, the palynological definition of the Norian/Rhaetian, Middle/Upper Jurassic and Jurassic/Cretaceous boundaries have still to be confirmed in other regions since suitable sections have not been available in Southern Germany.

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Résumé Dans le Mésozoïque moyen du Moyen Orient, six zones de spores peuvent être distinguées du Norien au Crétacé inférieur: Crétacé inférieur: Zone àIschyosporites variegatus — Rouseisporites laciniatus — Cicatricosisporites Jurassique supérieur: Zone àIschyosporites variegatus — Rouseisporites laciniatus Jurassique moyen: Zone àIschyosporites variegatus — Duplexisporites problematicus Jurassique inférieur: Zone àConcavisporites — Duplexisporites problematicus Réthien: Zone àConcavisporites — Duplexisporites problematicus — Lophotriletes sangburensis — Ricciisporites tuberculatus Norien: Zone àConcavisporites — Duplexisporites problematicus — Lophotriletes sangburensis — Cyclotriletes oligogranifer Une étude comparative montre que les mêmes zones de spores existent en Allemagne du sud et qu'elles correspondent aux limites faunistiques. Toutefois, les limites Norien/ Rhétien, Dogger/Malm et Malm/Crétacé inférieur demandent à être vérifiées.

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- : : Ischyosporites variegatus —Rouseisporites laciniatus — Cicatricosisporites : Ischyosporites variegatus — Rouseisporites laciniatus : Ischyosporites variegatus — Duplexisporites problematicus : Concavisporites — Duplexisporites problematicus : Concavisporites — Duplexisporites problematicus — Lophotriletes sangburensis — Ricciisporites tuberculatus : Concavisporites — Duplexisporites problematicus — Lophotriletes sangburensis — Cyclotriletes oligogranifer. , , . , /, / / .

     

Variations in diagenetic environments of the coral rag and underlying oolite of the osmington oolite formation (upper oxfordian) of the Oxford—Berkshire area,U.K., and their implications

Petrographic and geochemical evidence shows convincingly that the diagenetic environment changes from marine phreatic through freshwater phreatic to vadose during lithification of the oolites and the overlying Coral Rag of the Osmington Oolite Formation in the Oxford—Berkshire area. This change is thought to be a consequence of tectonic uplift following deposition of the Coral Rag. Extensive neomorphic replacement of the corals took place in a freshwater phreatic environment created by tectonic uplift. Retention of Sr in the Coral Rag is related to differing diagenesis: pore-fluids remained for protracted periods within the Coral Rag as the downward flow was greatly retarded because of obliteration of porosity in the oolites by marine phreatic cementation before deposition of the Coral Rag.     

Levels of organochlorine pesticide residues in some organs of the Ganges perch, Lates calcarifer, from the Ganges-Brahmaputra-Meghna Estuary, Bangladesh

Levels of organochlorine pesticide residues (p,p′ DDT, DDD, DDE, Aldrin, Dieldrin, Lindane, Heptachlor and BHC) were analysed in the dry and wet seasons in four organs (muscle, liver, gut and egg samples) of Ganges Perch, Lates calcarifer, collected during October–November–December, 1996 and May–June–July, 1997 from the Ganges–Brahmaputtra–Meghna estuary. The residues were analysed by using gas-chromatography (GC) in electron capture detector (ECD) mode and were verified by thin layer chromatography (TLC). Among the four organs analysed, the residues were found in the order egg > gut > muscle > liver. The pesticide residues were found in the order ∑DDT > Heptachlor >Dieldrin > Aldrin. Higher levels of residues were found during the dry season due to high lipid content in fishes. A positive correlation was observed between the pesticide residues (∑DDT and ∑OCs) and lipid contents of fish, and the correlation was found to be linear. The concentrations of pesticide residues in muscle, liver and gut were below the FAO/WHO (1993) recommended permissible limit except in eggs.