Filter Performance and Design for Highway Drains

The research is an investigation of soil filtration by geotextile fabrics, with the ultimate objective of improving design and long-term performance of underdrain systems in Indiana highways. Experiments were conducted in the laboratory using the best available techniques, Flexible Wall Gradient Ratio Test and Rapid Retention Test, in order to assess soil-filter compatibility and monitor geotextile clogging, for a range of materials and testing conditions. Field information was also collected and samples from highway reconstruction project were examined for their long-term performance. The main findings relate to the influence of the amounts of silt and clay and the state of compaction of the subgrade. Controlling parameters of the geotextile effectiveness are its opening size, thickness and manufacturing style. Based on these findings and information already available from the literature, new design and installation guidelines including filter selection criteria are proposed for non-woven geotextile filters in Indiana highway edge underdrain systems

Humanistic STEM: From Concept to Course

Blending perspectives from the humanities and STEM fosters the creativity of all students. The culturally implicit dichotomy between the two meta-disciplines can be overcome with carefully designed courses and programs intent on doing so. The why and how of doing so through an online course is described with qualitative evidence of the success. Future plans for a full slate of such course and a virtual community are discussed

Study of Side Ditch Liners for Highway Application

Over the past few years, the INDOT new materials department has received numerous erosion control products (mostly geosynthetics) to evaluate as alternatives to riprap and concrete in ditch liners. Potential benefits include lower construction costs and better aesthetics over current products. Unfortunately, no specification, design methodology, or classification system currently exists for these erosion control blankets. In this project\u27s phase I, existing information and knowledge on erosion control materials used to line highway side drainage ditches were investigated. From the available technical1iterature (journal and conference publications, other DOTs specifications, manufacturer documentation, independent test laboratory test data), design methodologies, classification system, product approval procedures, and installation methods were reviewed for temporary and permanent geosynthetic erosion control materials. Based on the synthesis of these reviews a design methodology was proposed including design aids (tables, flow charts, and graphs) necessary to perform flexible liner computations. A classification system based on product performance was also proposed. In addition, current design procedures for hard armor materials (fabric formed revetments, concrete block systems, gabions, and riprap) were reviewed. A tentative specification for both flexible and hard armor ditch liners was drafted

What Is Humanistic STEM and Why Do We Need It?

Getting students who are planning on technical careers to value their general education courses, particularly in the humanities, is not an easy task. The experiences of two professors from disciplines that cross the so-called divide between STEM and Humanities motivate not only a series of courses blending the two to the advantage of their own students but also a virtual pedagogical community to support efforts taking place elsewhere

A la recherche de la centralité perdue

Les mutations majeures de l'organisation de l'espace économique semblent remettre en question le concept de centralité et ses applications tout particulièrement à l'échelle de la ville, des réseaux de villes et de l'économie globalisée. L'étalement urbain fait émerger une centralité diffuse, multiple. La globalisation recompose les flux matériels et immatériels, et redistribue le pouvoir économique au bénéfice des villes globales. Une analyse précise des termes « centre » et « centralité » et des phénomènes qu'ils recouvrent permet de montrer que les schémas classiques, convenablement adaptés, restent pertinents à l'échelle des villes, mais que de nouveaux schémas de centralité apparaissent bien au niveau mondial, essentiellement sur une base réticulaire. / The major changes of economic space organization seem to cast doubt over the concept of centrality and its applications, especially at the city, city network and global economy scales. Urban sprawl gives rise to a diffused or multiple centrality. Economic globalization reorganizes material and immaterial flows, and redistributes economic power to the advantage of global cities. A precise analysis of the terms center and centrality and of the phenomena they refer to permits to show that the classical patterns, if they are properly adapted, remain relevant at the urban scale, but that new centrality patterns are emerging at the world scale, on a reticular basis.VILLE;MONDIALISATION;RESEAU;CENTRALITE

Investigation of Design Alternatives for the Subbase of Concrete Pavements

In all pavement structures, one or more support layers separate the pavement from the subgrade. In addition to offering structural support, these layers have several important functions, which include: providing a stable and uniform construction platform, facilitating drainage, mitigating pumping of the subgrade fines, and protecting the pavement from the effects of frost heave. Their performance is critical in achieving the desired pavement smoothness, and in extending the service life of the structure. A range of designs, making use of unbound or stabilized aggregates and in some cases geosynthetics, are employed by different agencies to fulfill these functions. This project was motivated by constructability and long term performance concerns with the existing base/subbase design employed by INDOT for concrete pavements, as well as the desire to identify state of the art design solutions that could be applicable to both concrete and asphalt pavements. The primary objectives of the study were to: critically reexamine INDOT’s existing design; perform a preliminary evaluation (based on aggregate compaction, hydraulic conductivity, strength and compatibility properties) of select unbound design options identified in collaboration with the Study Advisory Committee (SAC); explore the potential use of geotextiles as separator; and develop recommendations for base/subbase aggregate laboratory testing and evaluation

Analytical Study of the Nikawa Landslide

One of the most severe landslides triggered by the 1995 Hyogoken-Nambu earthquake was the Nikawa landslide. The seismic ground motion generated excessive pore pressure inside the portion of the slope mass that was below the water table. Data from standard penetration tests suggested that, in spite of the significant percentage of fines in the sand and its slight overconsolidation due to the fluctuation of the water table, the slope material had potential of liquefaction under seismic loading. The objective of the present study was to investigate the consistency between observations and the results of analysis methods for this slope failure. The methods of analysis were the conventional method of slices for static and pseudo-static computations, the Newmark method, and numerical modeling using the finite differences program FLAC. The constitutive behavior of the sand in FLAC analyses was represented by a modified Mohr-Coulomb model incorporating the equation proposed by Martin, Finn and Seed (1975) for the volumetric strain increments due to cyclic loading. Using this formulation, it is possible to simulate the pore pressure build-up due to dynamic loading in the portion of the sand layer located below the water table. Results are discussed and compared with observations

Measurements of Sheath Currents and Equilibrium Potential on the Explorer VIII Satellite (1960 xi)

Experimental data were obtained from the Explorer VIII satellite on five parameters pertinent to the problem of the interaction of space vehicles with an ionized atmosphere. The five parameters are: photoemission current due to electrons emitted from the satellite surfaces as a result of solar radiation; electron and positive ion currents due to the diffusion of charged particles from the medium to the spacecraft; the vehicle potential relative to the medium, and the ambient electron temperature. Included in the experimental data is the aspect dependence of the photoemission and diffusion currents. On the basis of the observations, certain characteristics of the satellite's plasma sheath are postulated

Parathyroid hormone-stimulated calcium absorption in cTAL from vitamin D-deficient rabbits

Parathyroid hormone-stimulated calcium absorption in cTAL from vitamin D-deficient rabbits. Cortical thick ascending limbs of Henle's loop were dissected from the kidneys of chronically vitamin D-deficient or -replete rabbits and perfused in vitro. Unidirectional transepithelial calcium fluxes from lumen to bath were measured with 45Ca. The tubules were bathed in a solution containing 150mM sodium and perfused with a solution containing 60mM sodium to simulate conditions in the cortical thick ascending limb in vivo. Transepithelial voltages were equal across tubules from vitamin D-deficient and -replete rabbits. Likewise, baseline and parathyroid hormone-stimulated calcium fluxes were the same in tubules from the two groups. Because calcidiol and calcitriol were undetectable in the serum of the vitamin D-deficient rabbits, we suggest that neither of these endogenous vitamin D metabolites is essential in the regulation of calcium absorption in this portion of the rabbit nephron