Two-phase SPH modelling of a real debris avalanche and analysis of its impact on bottom drainage screens

Rapid flow-like landslides, particularly debris flows and debris avalanches, cause significant economic damage and many victims worldwide every year. They are usually extremely fast with the capability of travelling long distances in short times, sweeping away everything in their path. The principal objective of this paper is to test the ability of the ‘GeoFlow-SPH’ two-phase model developed by the authors, to reproduce the complex behaviour of natural debris avalanches where pore-water pressure evolution plays a key role. To reach this goal, the model is applied to reproduce the complex dynamic behaviour observed in Johnsons Landing debris avalanche including the observed bifurcation caused by the flowing out of part of the moving mass from the mid-channel. Initial thickness deposit trim-line, distribution of deposit volume, and the average velocities were provided for this real case, making it an appropriate case to validate the developed model. The paper also contributes to evaluate the SPH-FD model’s potentialities to simulate the structural countermeasure, like bottom drainage screens, used to reduce the impact of debris flows. The analysis of the results shows the adequacy of the proposed model to solve this complicated geophysical problem.Fil: Tayyebi, Saeid M.. Universidad Politécnica de Madrid; EspañaFil: Pastor, Manuel. Universidad Politécnica de Madrid; EspañaFil: Stickle, Miguel M.. Universidad Politécnica de Madrid; EspañaFil: Yagüe, Ángel. Universidad Politécnica de Madrid; EspañaFil: Manzanal, Diego. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Tecnologías y Ciencias de la Ingeniería "Hilario Fernández Long". Universidad de Buenos Aires. Facultad de Ingeniería. Instituto de Tecnologías y Ciencias de la Ingeniería "Hilario Fernández Long"; Argentina. Universidad Politécnica de Madrid; EspañaFil: Molinos, Miguel. Universidad Politécnica de Madrid; EspañaFil: Navas, Pedro. Universidad Politécnica de Madrid; Españ

Frequency of inter- and intraventricular dyssynchrony in patients with heart failure according to QRS width

Aims: Cardiac resynchronization therapy (CRT) is an effective treatment for heart failure patients with prolongation of QRS duration. Despite careful patient selection, some do not respond to CRT based on QRS complex duration. We sought to evaluate the presence of left ventricular dyssynchrony using tissue Doppler imaging (TDI) according to QRS duration in heart failure patients. Methods and results: Ninety-nine patients (mean age 52.6 ± 15.3 years) with severe heart failure left ventricular (LV) ejection fraction, 40 ms and intra-LV mechanical delays (defined as Ts-SD >33.4 ms and Ts-diff >100 ms) were correlated with the QRS width and morphology. We found a greater IVMD in Group II patients, compared with patients in Group I (42.5 ± 22.3 vs. 26.8 ± 21, respectively, P 40 ms. Conclusion: A substantial proportion of patients with prolonged QRS (32.1%) did not exhibit inter- or intraventricular dyssynchrony, which may represent a limitation in identifying the ideal QRS interval for the selection of patients for CRT. © The Author 2007

Early septal activation, successful lateral ablation

The coronary sinus activation pattern is an important clue for the detection of arrhythmia mechanisms and/or localization of accessory pathways. Any change in this pattern during radiofrequency ablation should be evaluated carefully to recognize the presence of another accessory pathway or innocence of the accessory pathway during arrhythmia. Intra-atrial conduction block can change the coronary sinus activation pattern. Negligence regarding this phenomenon can cause irreversible complications. Here we describe a case with left lateral accessory pathway conduction in which intra-atrial conduction block completely reversed the coronary sinus activation pattern. Copyright © 2008 Via Medica

Agreement of Bitewing and Digital Panoramic Radiographies in the Detection of Proximal Caries

Abstract: Background & Aims: Conventional radiography is used for the diagnosis of problems such as dental caries and failure in root canal therapy. The diagnosis accuracy of conventional radiography is acceptable in the evaluation of anatomical and pathological structures. However, it seems that by using digital radiography we can obtain more information in this field. The aim of this study is to compare the diagnosis accuracy of bitewing radiography and digital panoramic imaging (filtered and unfiltered) in detection of proximal caries. Methods: This was a descriptive-analytical study which has evaluated 56 files of patients who were referred to a private office in Qazvin, Iran. These patients had digital panoramic (with CD) and bitewing radiographies in their records. The presence of decay and depth of decay were evaluated at the basis of 5-scale and 4-scale measurements, respectively. After collecting the data, data were entered into SPSS and ANOVA and Kappa coefficient were used. Values of P < 0.05 were considered significant. Results: The highest agreement in terms of presence or absence of caries based on location was obtained for bitewing (Kappa > 0.76), unfiltered panoramic, and filtered panoramic, respectively. General agreement between the two observers in terms of depth of caries was higher for panoramic views than bitewing radiography. Conclusion: According to the results of this study digital panoramic imaging, in spite of its digital imaging which the manufacturer claims can increase diagnostic accuracy, cannot be as accurate as bitewing radiography in detection of proximal caries. Thus, bitewing radiography is always the best option for evaluation of proximal surfaces. Keywords: Bitewing, Filtered panoramic, Unfiltered panoramic, Interproximal carie

Analyzing crop change scenario with the SmartScape spatial decision support system

Agricultural land use is increasingly changing due to different anthropogenic activities. A combination of economic, socio-political, and cultural factors exerts a direct impact on agricultural changes. This study aims to illustrate how stakeholders and policymakers can take advantage of a web-based spatial decision support system (SDSS), namely SmartScape™ to either test existing crop change policies or produce effective crop change decisions using tradeoff analysis. We addressed the consequences of two common crop change scenarios for Dane county in Wisconsin, United States, (a) replacing perennial energy crops with annual energy crops and (b) replacing annual energy crops with perennial energy crops. The results suggested that converting areas under grass and alfalfa production that were located on high quality soil and flat slope to corn promoted a net-income and availability of gross biofuel. Additionally, the model outcome proposed that converting areas under corn and soy production that were located on high slope to grass promoted net-energy, phosphorus loading, soil loss, soil carbon sequestration, nitrous oxide emission, grassland bird habitat, pollinator abundance, and biocontrol. Therefore, SmartScape™ can assist strategic crop change policy by comparing the tradeoff among ecosystem services to ensure that crop change policies have outcomes that are agreeable to a diversity of policymakers

Introducing a Relationship to Estimate Hydraulic Gradient in Non-Darcy Turbulent Flow in Porous Media

Introduction: Study of flow characteristics in rock porous media is one the most interesting issues for scientists and engineering dealing with river engineering works. So, there is no surprise that many models to describe the relationship between the flow velocity of clear water with hydraulic gradient, rock size, porosity, Reynolds number, and kinematic viscosity, have been introduced. Due to the large spaces between the coarse materials, flow velocity passing through the materials is high which in turn results in higher amounts of Reynolds number of flow. This type of flow classified as turbulent flow. Although Darcy law rules the flow in porous media, it is used for laminar flow in fine porous media and its application is not recommended for turbulent flows. Moreover, as the flow parameters in turbulent flows vary against time, the state of the flow is not steady. The equations describing the turbulent flows are obtained using equations defining basic concepts of hydrodynamics and turbulence effects. Due to complexity of the turbulent flow, these equations are described in the form of the partial differential equations. In order to introduce the specifications of this type of flow, various relationships have been provided by many researchers. However, their applications are confined to the limited conditions of porosity and size materials. In this study, we aim to provide a relationship which can be applied for a wide range of porosity and material size of porous media. Materials and Methods: To describe the relation between effective hydraulic parameters in coarse porous media, we used dimensional analysis theorem of Buckingham. In this regard six dimensionless parameters have been provided from which a relationship including four constant parameters has been obtained. We used a part of (70 percent) several available sets of data, provided from Soil Conservation and Watershed Management Research Institute, Irrigation and Reclamation Engineering Department of the University of Tehran, and mostly from published results, to find the magnitude of the constant parameters. So, we introduced a new equation which expresses a relationship between hydraulic gradient, porosity, and Froud number. Finally, using the remained part of (30 percent) available data, we compared the results of the new equation with those obtained from available models. Results and Discussion: To evaluate the new introduced equation and comparing the results obtained from the new equation and those obtained from available equations, we computed the magnitude of relative errors as well as the mean relative errors of the hydraulic gradient estimated from all equations versus the hydraulic gradients provided from field and laboratory observations. It is found that the new equation has the least mean of relative error (15.3 percent) among all equations. Moreover, for various magnitudes of rock size as well as porosity, we computed the mean relative error of estimated hydraulic gradients according to observed data. We found that the new equation has the second largest accuracy (with the mean error of 11.64%) among all evaluated models in this research. Finally, we developed two relationships between hydraulic gradient and Froud number using actual as well as apparent velocities. Again, it is found that the new relationship has the least mean of relative error (14.03 percent) among all equations. Conclusion: Since all available equations introduced to express the flow characteristics in coarse porous media, can be used in a defined limits of porosity, rock size, etc., in this research we aimed to provide a new relationship which can be used for a wider range of porous media specifications. So, based on dimensional analysis and using several sets of available field and laboratory data, a new equation has been introduced in this research which can be used for a wide range of rock size, Reynolds number, and porosity; i.e. rock diameter of 0.5 to 20 cm, Reynolds number greater than 100, and porosity of 0.35 to 0.55. Moreover, we introduced two equations to demonstrate the relationship between hydraulic gradient and actual velocity as well as apparent velocity. When we evaluated the results obtained from the new relationship with those obtained from some available equations, we found that the relative error of the new equation is 14 percent, which illustrates that the error of the results produced by the new equation is less than those produced by the available equations

Oil price movements and production agreements

The purpose of this technical exercise is to apply econometric modelling to study the relationship between movements in the oil price and compliance by the Organization of the Petroleum Exporting Countries (OPEC) with its self-assigned production agreements, whose purpose is to bring order and stability to the international oil market. Copyright 2004 Organization of the Petroleum Exporting Countries.