A fractal model for characterizing fluid flow in fractured rock masses based on randomly distributed rock fracture networks

A fractal model that represents the geometric characteristics of rock fracture networks is proposed to link the fractal characteristics with the equivalent permeability of the fracture networks. The fracture networks are generated using the Monte Carlo method and have a power law size distribution. The fractal dimension DT is utilized to represent the tortuosity of the fluid flow, and another fractal dimension Df is utilized to represent the geometric distribution of fractures in the networks. The results indicate that the equivalent permeability of a fracture network can be significantly influenced by the tortuosity of the fluid flow, the aperture of the fractures and a random number used to generate the fractal length distribution of the fractures in the network. The correlation of fracture number and fracture length agrees well with the results of previous studies, and the calculated fractal dimensions Df are consistent with their theoretical values, which confirms the reliability of the proposed fractal length distribution and the stochastically generated fracture network models. The optimal hydraulic path can be identified in the longer fractures along the fluid flow direction. Using the proposed fractal model, a mathematical expression between the equivalent permeability K and the fractal dimension Df is proposed for models with large values of Df. The differences in the calculated flow volumes between the models that consider and those that do not consider the influence of fluid flow tortuosity are as high as 17.64-19.51%, which emphasizes that the effects of tortuosity should not be neglected and should be included in the fractal model to accurately estimate the hydraulic behavior of fracture networks

Effects of compartmental model structure and long-term inflow on model predictions

Model predictions of solute transport in a wetland were compared with tracer experimental data to illustrate that the number of compartments in a compartmental model should be selected according to certain rules to accurately describe the transport process. If the input pulse is short, the model structure affects the output significantly. The temporal moments of the residence time distribution was obtained from a general solution of the compartmental model in the Laplace domain derived with an arbitrary inflow pollutograph. The variance of the residence time can be used as a useful tool to analyse the effect of model structure and long-term inflow pollutograph on the response of the model predictions.QC 2012011

Prediction of concentration and model validation

In this paper we examine some critical aspects concerning the justification of simplified radioecological models used in safety assessments for geological repositories. We propose a modelling approach for regulatory review of dose and risk calculations for a nuclear waste repository. The SSI modelling tools are applied to explore uncertainties in the size of the contaminant area due to leakage of radionuclides from a damaged nuclear waste canister. We demonstrate that an improved representation of geosphere transport processes will also enhance our understanding of radionuclide migration in the biosphere and provide a better basis for evaluating radiological consequences in the safety assessment.Qc 2012012

Developing The Semantic Web Application In Java

Maģistra darba “Semantiskā tīmekļa aplikācijas izstrāde valodā Java” praktiskais mērķis ir tādas semantiskā tīmekļa aplikācijas realizācija, kas ļautu veidot saturu RDF (Resource Description Framework) formātā. Darbā aprakstīta autora realizētās aplikācijas uzbūve un funkcionalitāte. Darba pirmajā nodaļā tiek apskatīti semantiskā tīmekļa teorētiskie aspekti un aprakstītas semantiskā tīmekļa tehnoloģijas. Otrajā nodaļā tiek specificētas veidojamās aplikācijas prasības, sniegts ieskats izvēlētajās izstrādes tehnoloģijās, kā arī aprakstīti vispārējie aplikācijas uzbūves principi. Trešajā nodaļā detalizēti tiek aprakstīta aplikācijas darbība, izklāstītas realizācijas procesā radušās problēmas un to risinājumi un piedāvāti turpmākie aplikācijas attīstības varianti.The practical goal of the work is to create fully functional semantic web application that would allow user to manage semantic web content and store the created data using Resource Description Framework. Master paper “Developing The Semantic Web Application In Java” provides detailed description of the architecture and functionality of the implemented application. The first chapter of the paper deals with the theoretical aspects of semantic web and related technologies. In the second chapter author gives the requirement specification for the future application, describes the architecture of the application and the technologies used for implementation. In the third chapter author reveals the details of implementation, outlines the problems experienced during development and also describes possible future improvements for application

Potential for high transient doses due to accumulation and chemical zonation of long-lived radionuclides across the geosphere-biosphere interface

Planning for the disposal of spent nuclear fuel is at an advanced stage in several nations around the world. Licensing of the disposal facility requires correspondingly detailed assessment of the future performance of the facility. With increased site-specific detail available to the assessment, local characteristics play an increasingly important role in determining the potential radiological risk posed by releases to the biosphere. In this paper we go beyond existing reference biosphere models and investigate the potential for specific accumulation mechanisms. The implications for the modelling carried out in long timescale performance assessment are discussed