Homogeneous Sections Research Articles

Effects of Karst and geological structure on groundwater flow: The case of Yarqon-Taninim Aquifer, Israel

This study demonstrates the significant influences of the geological structure (especially folding and lithology) and the karst system on groundwater flow regime. Folds divert groundwater flow from the general hydraulic gradient; marly layers sustain several perched sub-aquifers above the regional aquifer; and karstification increases the hydraulic conductivity by several orders of magnitude. These phenomena are quantitatively demonstrated within the Yarqon-Taninim (YT) basin, Israel, which is a complex groundwater system, combining several (extremely) opposite characteristics: humid and arid recharge zones, phreatic and confined parts, shallow and deep sub-aquifers, stratified and relatively-homogeneous sub-basins, saline and fresh water bodies, as well as stagnant and fast-flowing groundwater regions. We have introduced a 3D geological-based grid for the basin (for the first time). It was implemented into a numerical code (FEFLOW), which was used thereafter to analyze quantitatively the flow regime, the groundwater mass balance, and the aquifer hydraulic properties. We present up to date conceptual understanding and numerical modeling of the YT flow field, especially at its mountainous parts. Based on the calibration procedure and the sensitivity analyses, we obtained the best-fitted hydraulic conductivity values for the aquifer mesh. The general phenomenon observed is that as groundwater flow quantity increases, the hydraulic conductivity also increases. We interpret this result by the karstification mechanism (including paleo-karst). Thus, where groundwater flow-lines converge and where groundwater discharge amount increases, the karstification process intensifies and permeability increases. Consequently, at the mountainous region, along the syncline axes, where groundwater flow-lines converge, higher conductivities are found. Modeling results also exhibit that at the lowland confined area, the geological structure does not play a major role in directing groundwater flow. Rather, the flow field is controlled by the well-developed karst system and the relatively homogenous carbonate section. It is hypothesizes that the extensive karstification took place at the Messinian Salinity Crises, ∼5.5 Ma, during which groundwater heads as well as sea level were lowered by several 100 m.

Development of comprehensive accident models for two-lane rural highways using exposure, geometry, consistency and context variables

In Europe, approximately 60% of road accident fatalities occur on two-lane rural roads. Thus, research to develop and enhance explanatory and predictive models for this road type continues to be of interest in mitigating these accidents. To this end, this paper describes a novel and extensive data collection and modeling effort to define accident models for two-lane road sections based on a unique combination of exposure, geometry, consistency and context variables directly related to the safety performance. The first part of the paper documents how these were identified for the segmentation of highways into homogeneous sections. Next, is a description of the extensive data collection effort that utilized differential cinematic GPS surveys to define the horizontal alignment variables, and road safety inspections (RSIs) to quantify the other road characteristics related to safety. The final part of the paper focuses on the calibration of models for estimating the expected number of accidents on homogeneous sections that can be characterized by constant values of the explanatory variables. Several candidate models were considered for calibration using the Generalized Linear Modeling (GLM) approach. After considering the statistical significance of the parameters related to exposure, geometry, consistency and context factors, and goodness of fit statistics, 19 models were ranked and three were selected as the recommended models. The first of the three is a base model, with length and traffic as the only predictor variables; since these variables are the only ones likely to be available network-wide, this base model can be used in an empirical Bayesian calculation to conduct network screening for ranking “sites with promise” of safety improvement. The other two models represent the best statistical fits with different combinations of significant variables related to exposure, geometry, consistency and context factors. These multiple variable models can be used, with caution, and in conjunction with results from other studies, to derive accident modification factors for these variables for design applications, and in safety assessment for smaller samples of sites for which these variables can be assembled with relative ease.

Integrating the Impact of Rain into Traffic Management

A new approach to the integration of the effects of inclement weather into traffic management strategies is presented. Adverse weather conditions are a critical factor affecting traffic operations and safety. Previously, a methodology for the analysis of the impact of rain has been addressed, and this impact on key traffic indicators (e.g., free-flow speed, capacity) has been quantified. As a result of these quantification studies, a first parameterization of the fundamental diagram according to rain intensity has been proposed. Since the fundamental diagram represents the basis of many simulation tools, the goal is to develop weather-responsive traffic state estimation tools that can be useful for control applications and traffic management. More precisely, the online traffic state estimation takes place within a Bayesian framework with particle-filtering techniques (i.e., sequential Monte Carlo simulations) in combination with a parameterized first-order macroscopic model. This approach has already been validated for sensor diagnosis and accident detection. In this paper the goal is to show how the integration of the weather effects can improve this efficient tool. The approach is validated with real-world data from the ring road section in Lyon, France (eight sensors from a homogeneous section). The results from different scenarios show the benefits of integrating the impact of rain into traffic state estimation. Strategies to detect a rain event in time and space are also suggested.

Near surface carbon dioxide within the urban area of Essen, Germany

The aim of this investigation was to determine the allocation between carbon dioxide concentrations, by mobile measurements at 1.5 m a.g.l., within the urban canopy layer regarding different conditions: anticyclonic and cyclonic weather situations, on weekdays, at different times of the day and in different seasons. During winter 2002/2003 (December–February) and summer 2003 (June–August) 20 high frequency spatial and temporal mobile measurements of carbon dioxide were taken in the city of Essen (51° 28′N, 7° 0′E, North Rhine-Westphalia, Germany). The route of the taken measurements started in the southern part of the city and ended after 63 km in the north of Essen, considering all different kinds of its land utilization. The contribution of motor vehicles to the carbon dioxide concentration was being determined by calculating the relation of carbon dioxide to other atmospheric substances, such as CO, NO, NO 2 and O 3. All atmospheric substances were captured at the same time and height with a measurement frequency of 1 Hz and a maximum travel speed of 30 km h −1 (8 m s −1). The results of each mobile measurement were condensed to average values for homogeneous route sections. This facilitated a comparison of the urban CO 2 concentration between the CO 2-data of a rural station and the results of a base line station maintained by the Federal Environmental Agency (UBA). With assistance of different statistical methods it was possible to testify that the determined CO 2-data are representative for the situation of the air quality in the city of Essen. The results of this investigation have shown that it is neither generally possible to describe the urban area as a permanent anthropogenic source for CO 2 nor to call it an urban CO 2 dome as it is often mentioned in literature (e.g. Idso et al., 1998, 2001). A comparison of the carbon dioxide mixing ratio of the city of Essen and the rural station, maintained by the Dept. of Applied Climatology and Landscape Ecology, demonstrated that the city exceeds the rural station for less than 30% per season.

The Influence of Timber Panels on Architecture

Since timber is naturally directional, timber products become directionally neutral only due to the progress in manufacture technology. This work studies timber panels with a view to analyse their influence on the architectural form. From a design point of view, two sub-categories are defined. These are solid panels, and optimised panels. Solid panels have a homogeneous and compact section and their thicknesses are relatively small. Composite panels are generally made up with two boards and an inner structure to which they are bonded. The work concludes that the two main typologies of timber panels influence design in a different way: due to their homogeneous inner structure, solid panels allow flexible cutting of the openings, and loads and supports can be placed with few limitations. In the other hand, optimised section panels require more planning and should be treated as finished elements.

Hybrid technique for analysing metallic waveguides containing isotropic chiral materials

A novel full-wave hybrid technique was formulated to treat three-dimensional discontinuities in isotropic chiral materials present in rectangular waveguides with perfect electrically conducting walls. Our formulation comprises (i) the coupled-mode method for obtaining the electromagnetic field in each section that is homogeneous in the propagation direction and (ii) the mode-matching method for obtaining the generalised scattering matrix of each discontinuity (formed by two adjacent homogeneous sections). In particular, we reformulated the coupled-mode method based on appropriate representations of E and B. This formulation ensures the satisfaction of the boundary conditions of the magnetic field on perfect electrically conducting walls, which is not ensured by the conventional formulation of the coupled-mode method as it is based on representations of E and H. A new expansion for H emerges indirectly from our formulation. Knowledge of this expansion is required by the mode-matching method for incorporating the effects of discontinuities between adjacent homogeneous sections. Calculations confirmed that our new formulation delivers correct results, whereas the conventional formulation may not.

Unsteady behavior of an elastic articulated beam floating on shallow water

The unsteady behavior of an elastic beam composed of hinged homogeneous sections, which freely floats on the surface of an ideal incompressible fluid, is studied within the framework of the linear shallow water theory. The unsteady behavior of the beam is due to incidence of a localized surface wave or initial deformation. Beam deflection is sought in the form of an expansion with respect to eigenfunctions of oscillations in vacuum with time-dependent amplitudes. The problem is reduced to solving an infinite system of ordinary differential equations for unknown amplitudes. The beam behavior with different actions of the medium and hinge positions is studied.

Effects of Pavement Spatial Variability on Contractor’s Management Strategies

Performance-based maintenance contracts are becoming an increasingly popular method of outsourcing pavement maintenance work. These contracts transfer performance-related risks to contractors with the objective of reducing the total cost of maintenance over the pavement life cycle by leveraging on the efficiencies of private sector management. In such contractual settings, transportation agencies hedge their exposure to poorly performing pavements that require frequent attention. However, this comes with a price. Contractors price in their bids a premium to account for such scenarios. This paper presents a model for contractors to determine optimal management strategies by taking into account the inherent spatial variability in pavement’s structural characteristics. The model considers a tradeoff between economies of scale associated with managing longer pavement sections and the risk reduction benefits with managing relatively smaller, e.g., more homogeneous sections. The results indicate that the length of optimal management sections depends not only on the expected contract penalty costs (disincentive costs), but also the ability of the contractor to explore economies of scale. The model is illustrated using typical data available to transportation agencies.

Effect of axial restraint in composite bars under nonlinear inelastic uniform torsion by BEM

In this paper, the effect of axial restraint in the elastic–plastic uniform torsion analysis of cylindrical bars taking into account the effect of geometric nonlinearity is presented employing the boundary element method. The bar is axially elastically supported at the centroids of its end cross sections, treating the cases of free axial boundary conditions (vanishing axial force), restrained axial shortening or given axial force as special ones. The cross section of the bar is an arbitrary doubly symmetric composite one, consisting of materials in contact, each of which can surround a finite number of inclusions, while the case of a homogeneous cross section is treated as a special one. The stress–strain relationships for the materials are assumed to be elastic–plastic-strain hardening. The incremental torque–rotation relationship is computed based on the finite displacement (finite rotation) theory, that is the transverse displacement components are expressed so as to be valid for large rotations and the longitudinal normal strain includes the second-order geometrically nonlinear term, often described as the “Wagner strain”. The proposed formulation does not stand on the assumption of a thin-walled structure and therefore the cross section’s torsional rigidity is evaluated exactly without using the so-called Saint-Venant’s torsional constant. The torsional rigidity of the cross section is evaluated directly employing the primary warping function of the cross section depending on both its shape and the progress of the plastic region. A boundary value problem with respect to the aforementioned function is formulated and solved employing a BEM approach. The developed procedure retains most of the advantages of a BEM solution over a pure domain discretization method, although it requires domain discretization, which is used only to evaluate integrals. The significant increase of the torsional rigidity of the bar and the arising axial force due to the axial restraint are concluded.

Fundamental Diagram Modelling and Analysis Based NGSIM Data

Abstract Traffic control requires looking at traffic models of all types in finer details. This paper is to investigate lane-wise flow-density (or equivalently speed-density) relationship which is traditionally called Fundamental Diagram (FD) over a stretch of homogeneous freeway section using the microscopic NGSIM data. Particularly, it investigates how a homogenous traffic further drop (breakdown) through data analysis and modeling. The breakdown of a homogenous traffic is understood as the significant flow drop and density increase with noticeable shock-wave back-propagation. The corresponding density is a generalization of the critical density for traffic breakdown from free-flow. Variable structure models with two limbs of the inverse λ – shape are proposed to model the homogenous flow and its further drop. A special Generalized Polynomial Model (with fraction coefficients) is also proposed for the right limb. Properly aggregated NGSIM data are used to fit the model with results compared with some other models over time at fixed location using Root Mean Square Errors (RMSE) as measure. Principles for time/distance aggregation of individual vehicle trajectories to macroscopic traffic state parameters are proposed.

Semi-analytical dual edge element method and its application to waveguide discontinuities

A semi-analytical dual edge element is proposed to solve the waveguide discontinuities. The governing equations for electromagnetic waveguide are converted to the Hamiltonian system, and the corresponding variational principle based on the dual variables is given. For waveguide sections which are homogeneous along the longitudinal direction, the dual edge element is employed to discretize the cross section, and a precise integration method based on the Riccati equations is used for the longitudinal integration to generate the export stiffness matrices. The whole waveguide discontinuity problems can be solved by combining the export stiffness matrices of homogeneous waveguide sections with the system matrices by conventional three-dimentional finite element method for inhomogneous waveguide sections. Numerical examples demonstrate the high accuracy and efficiency of this method for solving waveguide discontinuity problems.

A high‐resolution relative time scale for the Viséan Stage (Carboniferous) of the Kulm Basin (Rhenish Mountains, Germany)

AbstractThe Viséan (Carboniferous) sedimentary succession of the basinal Kulm facies (Rhenish Mountains) was investigated in detail in order to achieve a high‐resolution stratigraphic subdivision and correlation. Additionally, the ranges of fossil index taxa (ammonoids), fossil marker beds, volcaniclastic horizons and sedimentary features (e.g. colour changes) were integrated in the correlation. As a result, a comprehensive database was compiled, which contains 190 stratigraphic events of the Viséan interval of this area.Several sections are almost completely composed of shales, which are regarded to represent a slow but constant basinal background sedimentation of the Kulm facies. The thickness of lithological homogeneous sections thus indicates an approximately linear record of time and the average thicknesses of biozones and positions of stratigraphic events can easily be calculated from the compiled database. The result is an approximately time‐linear biostratigraphic scale for the Viséan Stage of the Kulm Basin. Given a numerical length of the Viséan Stage of ca. 19 Ma, 190 stratigraphic events give a mean resolution of 100 000 years. This is unique in Palaeozoic stratigraphy. Copyright © 2008 John Wiley & Sons, Ltd.

On Jarava, or putting the cart before the horse

AbstractThe change of circumscription of Jarava (Stipeae) from a morphologically homogeneous section with nine species of the genus Stipa to a heterogeneous genus of ca. 60 species is criticized because of the lack of DNA data to support the change. The modification is considered inconvenient in terms of the ICBN article 14.1 on disadvantageous strict application of priority rules, due to the abundance of Stipa in South American arid regions, a fact which is reflected in the extensive use of the name Stipa by Latinamerican botanists.

Optimal design and operation of a natural gas tri-reforming reactor for DME synthesis

Korea Gas Corporation (KOGAS) is developing a new di-methyl-ether (DME) plant. Syngas is provided by natural gas tri-reforming, in a reactor consisting of a homogenous part where oxidation leads to a temperature increase required for the reforming reactions and a catalytic part where the reforming reactions take place. A first principle model for the tri-reforming reactor is developed. A kinetic mechanism is proposed combining homogeneous gas-phase reactions and heterogeneous catalytic reactions. The proposed model is systematically calibrated and validated with global sensitivity analysis followed by global parameter estimation against concentration measurements of a lab-scale prototype reactor and comparisons of the sensitivity of the outlet as a function of inlet composition and design parameters with experimental results. The validated model is finally used for the optimization of design variables such as length ratio of homogeneous and heterogeneous section and operational variables such as the feed composition.

Geometry of all supersymmetric four-dimensional 𝒩 = 1 supergravity backgrounds

We solve the Killing spinor equations of ${\cal N}=1$ supergravity, with four supercharges, coupled to any number of vector and scalar multiplets in all cases. We find that backgrounds with N=1 supersymmetry admit a null, integrable, Killing vector field. There are two classes of N=2 backgrounds. The spacetime in the first class admits a parallel null vector field and so it is a pp-wave. The spacetime of the other class admits three Killing vector fields, and a vector field that commutes with the three Killing directions. These backgrounds are of cohomogeneity one with homogenous sections either $\bR^{2,1}$ or $AdS_3$ and have an interpretation as domain walls. The N=3 backgrounds are locally maximally supersymmetric. There are N=3 backgrounds which arise as discrete identifications of maximally supersymmetric ones. The maximally supersymmetric backgrounds are locally isometric to either $\bR^{3,1}$ or $AdS_4$.

Coronal Loop Model Including Ion Kinetics

We present a kinetic coronal loop model including collisions and wave-particle interactions to study the mechanisms of loop heating. The model is based on a quasi-linear treatment of the Vlasov equation for the reduced velocity distribution functions of the protons, which are the only ions considered in the loop plasma. For the energy input into the loop, we assume that linear Alfven waves penetrate the loop from its footpoints and heat the protons via wave-particle interactions and wave absorption. Through Coulomb collisions between protons and electrons some thermal energy can be transferred to the electrons. It turns out that in such a model protons are hotter than electrons, and the scale length for proton heating along the loop is determined by the dissipation scale of the ion-cyclotron waves. Through the gyrofrequency this scale is connected to the cross section area of the loop and, thus, to the spatial variation of the magnetic field shaping the coronal loop. Furthermore, it is shown that in the case of a nearly homogeneous flux tube cross section, an almost flat temperature profile occurs along the major part of the loop with an enhanced plasma density. These plasma parameter profiles are consistent with those of loops having temperatures between 1 and 1.5 MK as observed in extreme-ultraviolet emission. However, if the magnetic field lines are more strongly diverging from the footpoints to the loop apex, the proton heating is found to be more uniform, resulting in a higher temperature and lower density along the loop. These profiles are similar to those observed in X-ray loops.

Quantitative morphodynamic typology of rivers: a methodological study based on the French Upper Rhine basin

AbstractThis study sought to establish a quantitative functional hydrogeomorphological typology of river reference types in the French Upper Rhine basin that would meet the requirements of the European Water Framework Directive, defined in terms of hydromorphological quality and prospects for river restoration. Four ecoregions (i.e. hydrogeomorphic units) were delineated by expert opinion and validated by independent variables (i.e. 1·5‐year peak discharge, comparison of 10‐year daily flow and low flow, valley bottom morphology and specific stream power). A data set of 31 quantitative and qualitative variables for 187 field sites was established and analysed. Agglomerative hierarchical clustering (AHC) of the quantitative variables and principal component analysis (PCA) provided hierarchy and grouping of variables. Multiple correspondence analysis (MCA) confirmed these results, discriminating sites into seven groups, but did not lead to a functional typology due to important overlapping between groups and variability within groups. A definitive quantitative typology was obtained through AHC and discriminant analysis with cross‐validation computed separately in each ecoregion. Results for two ecoregions, ‘marly calcareous loess‐covered hills’ and ‘crystalline Vosges mountains’, are given as examples. Finally, the classification of the sites is extended to the whole river network by river sectorization, each homogeneous river section being classified to one category on the basis of the preceding classification of sites. Methodological implications regarding river classification are also given. Copyright © 2007 John Wiley & Sons, Ltd.

Generalization-oriented Road Line Classification by Means of an Artificial Neural Network

In line generalization, a first goal to achieve is the classification of features previous to the selection of processes and parameters. A feed forward backpropagation artificial neural network (ANN) is designed for classifying a set of road lines through a supervised learning process, attempting to emulate a classification performed by a human expert for cartographic generalization purposes. The main steps of the process are presented in this paper: (a) experimental data selection; (b) segmentation of lines into homogeneous sections, (c) sections enrichment through a set of quantitative measures derived from a principal component analysis, and qualitative information derived from road network and road type; (d) expert classification of the sections; and finally (e) the ANN design, training and validation. The quality of results is analyzed by means of error matrices after a cross-validation process giving a goodness, or percentage of agreement, over 83%.

Streaming potential and electroviscous effect in heterogeneous microchannels

This communication presents a theoretical analysis of the streaming potential and the electroviscous effect on pressure-driven flow in heterogeneous microchannels. Compact formulae in terms of phenomenological coefficients are derived for the streaming potential and the apparent viscosity ratio in channels with surface charge variations perpendicular and parallel to the applied pressure gradient. In the latter case, the streaming potential per unit liquid flow in a multi-section channel is found to be simply the summation of that in each homogeneous section. The apparent viscosity ratio is a weighted average of each section where the hydrodynamic resistance serves as the weighting factor. The phenomenological coefficients are specified using electrokinetic flow analysis, through which the streaming potential and electroviscous effect in a two-section slit channel are examined. It is found that they both depend on the arrangement of surface heterogeneity in small microchannels. This dependence, however, gets weak in large microchannels, which is consistent with the prediction of thin double layer approximation.

Protein Expression within the Human Renal Cortex and Renal Cell Carcinoma: The Implication of Cold Ischemia

Cold ischemia of tissue during tissue treatment may influence protein expression, but has not been well studied. Better understanding of this is fundamental prior to using stored fresh-frozen tissue where the time from organ harvest until tissue collection and storage is most often not documented. We collected samples from normal renal cortex and cancerous tissues at serial time points for up to 60 min from three nephrectomized individuals with newly diagnosed clear cell renal cell carcinoma (RCC). Samples were processed onto protein chips and identified using surface-enhanced laser desorption/ionization-time of flight mass spectrometry (SELDI). The number and size of proteins expressed at separate sites within homogenous tissue sections were comparable. Cold ischemia time neither affected the number nor the size of proteins expressed. While the quantity of most proteins was similar between separate sites and unaffected by cold ischemia time, we noted variation in the quantity of some proteins compared to...