Optimal Placement of Water Quality Monitoring Stations in Sewer Systems: An Information Theory Approach

A core problem associated with the water quality monitoring in the sewer system is the optimal placement of a limited number of monitoring sites. A methodology is provided for optimally design water quality monitoring stations in sewer networks. The methodology is based on information theory, formulated as a multi-objective optimization problem and solved using NSGA-II. Computer code is written to estimate two entropy quantities, namely Joint Entropy, a measure of information content, and Total Correlation, a measure of redundancy, which are maximized and minimized, respectively. The test on a real sewer network suggests the effectiveness of the proposed methodology

Effects of rock mass anisotropy on deformations and stresses around tunnels during excavation

rock mass where the in situ state of stress is uniform. The rock mass was assumed to behave elastically and two cases were examined: whether the rock mass has an isotropic elastic property or not. A two-dimensional plain strain elastic-plastic Jointed Rock model was used to study the response of the rock mass to excavation. The elastic behaviour of the rock mass was assured in the model by simply providing adequate cohesion. The study reveals that the distribution of excavation-inducedstresses and deformations in the space surrounding rock mass having anisotropic properties differs from that obtained under the assumption of isotropic properties. The neglect of the effect of elastic anisotropy can result in a significant underestimation of stresses and displacements in rock and thus also in the design of support measures and the final pressure tunnel linings. Additionally, when the tunnel geometry is circular and the rock mass contains one joint set where the plane of elastic anisotropy strikes to the tunnel axis, the results obtained for one dip angle will be identical to another dip angle by rotating the x- and y-axis accordingl

The construction of confidence intervals for frequency analysis using resampling techniques

International audienceResampling techniques such as the Bootstrap and the Jack-knife are generic methods for the estimation of uncertainties in statistics. When applied in frequency analysis, resampling techniques can provide estimates of the uncertainties in both distribution parameters and quantile estimates in circumstances in which confidence limits cannot be obtained theoretically. Test experiments using two different parameter estimation methods on two types of distributions with different initial sample sizes and numbers of resamples has confirmed the utility of such methods. However, care is necessary in evaluating the skewness of the resampled quantiles, especially with small initial sample sizes. Keywords: Bootstrap, Jack-knife, frequency analysis, maximum likelihood method, maximum product of spacings metho

Diversity of vibrissal follicle anatomy in cetaceans

Most cetaceans are born with vibrissae but they can be lost or reduced in adulthood, especially in odontocetes. Despite this, some species of odontocetes have been found to have functioning vibrissal follicles (including the follicle itself and any remaining vibrissal hair shaft) that play a role in mechanoreception, proprioception and electroreception. This reveals a greater diversity of vibrissal function in odontocetes than in any other mammalian group. However, we know very little about vibrissal follicle form and function across the Cetacea. Here, we qualitatively describe the gross vibrissal follicle anatomy of fetuses of three species of cetaceans, including two odontocetes: Atlantic white-sided dolphin (Lagenorhynchus acutus), harbour porpoise (Phocoena phocoena), and one mysticete: minke whale (Balaenoptera acutorostrata), and compared our findings to previous anatomical descriptions. All three species had few, short vibrissae contained within a relatively simple, single-part follicle, lacking in muscles. However, we observed differences in vibrissal number, follicle size and shape, and innervation distribution between the species. While all three species had nerve fibers around the follicles, the vibrissal follicles of Balaenoptera acutorostrata were innervated by a deep vibrissal nerve, and the nerve fibers of the odontocetes studied were looser and more branched. For example, in Lagenorhynchus acutus, branches of nerve fibers travelled parallel to the follicle, and innervated more superficial areas, rather than just the base. Our anatomical descriptions lend support to the observation that vibrissal morphology is diverse in cetaceans, and is worth further investigation to fully explore links between form and function

Design of pressure tunnels using a finite element model

In this study, a two-dimensional plane strain finite element model is used for the prediction of mechanical and hydraulic behaviour of pre-stressed concrete-lined pressure tunnels. Results obtained from numerical models are presented and compared with the one calculated using analytival solutions

Mechanical-hydraulic interaction in the lining cracking process of pressure tunnels

Pressure tunnels are in operation subjected to internal water pressure. When the hoop tensile stress acting at the lining intrados exceeds the tensile strength of concrete, longitudinal cracks occur in the concrete lining. As a consequence of crack openings, the internal water pressure will act at the lining extrados and cause high local water losses. If left untreated, these losses will induce the washing out of joint fillings and increase the risk of hydro-jacking of the surrounding rock mass. When pressure tunnels are situated close to valley slopes, excessive water losses can endanger the stability of the rock mass and provoke landslide. Whether or not the internal water pressure is fully effective at the lining extrados, it depends predominantly on the number of cracks and the width of crack openings. The width of cracks can be estimated based on the total circumferential deformation of the rock mass, which is governed not only by mechanical boundary pressures, but also by seepage pressures. In turn, seepage pressures generate water losses from the tunnel, which are depending not only on the permeability of the rock mass, the grouted zone, and the concrete lining, but also, if any, on the width of the crack openings. The estimation of pressures transmitted to the rock mass requires therefore solutions using iterative methods dealing with this coupling behaviour. This paper presents a method to estimate the distribution of seepage pressures and water losses around concretelined pressure tunnels pre-stressed by grouting, which considers the lining cracking process due to a high internal water pressure. The mechanical and hydraulic behaviour of cracked concrete-lined pressure tunnels is presented so as a first step for more elaborate numerical studies

Metabolic engineering of the iodine content in Arabidopsis

Plants are a poor source of iodine, an essential micronutrient for human health. Several attempts of iodine biofortification of crops have been carried out, but the scarce knowledge on the physiology of iodine in plants makes results often contradictory and not generalizable. In this work, we used a molecular approach to investigate how the ability of a plant to accumulate iodine can be influenced by different mechanisms. In particular, we demonstrated that the iodine content in Arabidopsis thaliana can be increased either by facilitating its uptake with the overexpression of the human sodium-iodide symporter (NIS) or through the reduction of its volatilization by knocking-out HOL-1, a halide methyltransferase. Our experiments show that the iodine content in plants results from a balance between intake and retention. A correct manipulation of this mechanism could improve iodine biofortification of crops and prevent the release of the ozone layer-threatening methyl iodide into the atmosphere

The Niger Delta's vulnerability to river floods due to sea level rise

An evaluation of vulnerability to sea level rise is undertaken for the Niger Delta based on 17 physical, social and human influence indicators of exposure, susceptibility and resilience. The assessment used geographic information systems (GIS) techniques to evaluate and analyse the indicators and the index of coastal vulnerability to floods, if sea level rise conditions are occurring. Each indicator value is based on data extracted from various sources, including remote sensing, measured historical data series and a literature search. Further on, indicators are ranked on a scale from 1 to 5 representing "very low" to "very high" vulnerability, based on their values. These ranks are used to determine a similar rank for the defined coastal vulnerability index (CV_SLRI). Results indicate that 42.6% of the Niger Delta is highly vulnerable to sea level rise, such areas being characterised by low slopes, low topography, high mean wave heights, and unconfined aquifers. Moreover, the analysis of social and human influences on the environment indicate high vulnerability to sea level rise due to its ranking for type of aquifer, aquifer hydraulic conductivity, population growth, sediment supply and groundwater consumption. Such results may help decision makers during planning to take proper adaptive measures for reducing the Niger Delta's vulnerability, as well as increasing the resilience to potential future floods

The Niger Delta's vulnerability to river floods due to sea level rise

An evaluation of vulnerability to sea level rise is undertaken for the Niger Delta based on 17 physical, social and human influence indicators of exposure, susceptibility and resilience. The assessment used geographic information systems (GIS) techniques to evaluate and analyse the indicators and the index of coastal vulnerability to floods, if sea level rise conditions are occurring. Each indicator value is based on data extracted from various sources, including remote sensing, measured historical data series and a literature search. Further on, indicators are ranked on a scale from 1 to 5 representing “very low” to “very high” vulnerability, based on their values. These ranks are used to determine a similar rank for the defined coastal vulnerability index (CVSLRI). Results indicate that 42.6% of the Niger Delta is highly vulnerable to sea level rise, such areas being characterised by low slopes, low topography, high mean wave heights, and unconfined aquifers. Moreover, the analysis of social and human influences on the environment indicate high vulnerability to sea level rise due to its ranking for type of aquifer, aquifer hydraulic conductivity, population growth, sediment supply and groundwater consumption. Such results may help decision makers during planning to take proper adaptive measures for reducing the Niger Delta’s vulnerability, as well as increasing the resilience to potential future floods