This thesis examines the impact of spillway surface roughness on discharge capacity determination in hydraulic models. The study combines physical hydraulic modeling in a laboratory with Computational Fluid Dynamics (CFD) modeling using Fluent. The aim is to evaluate the effect of material roughness on spillway discharge determination for prototype spillways and outlets. The project includes a literature review, data collection, 3D modeling, model setup, numerical modeling, result analysis, comparison with other reports, and report writing. The results concluded that varying roughness heights as well as changing turbulence model and mesh settings did not significantly impact the final discharge (kg/s) at steady state. P-values less than 1e-7 for the average discharge at flowtime of [150 − tfinal[s]] suggests strong confidence in the statistical insignificance of varying roughness height affecting the discharge.

The focus of the project was to alter and optimize the water repellant textile coating formulations to reach enhanced durability. For this purpose, the project was approached with three methods. Firstly, bio-based components were implemented in the mother emulsion to act as surfactant and crosslinking agent and to provide hydrophobic properties. Secondly different binders were added to crosslink and increase the coating resistance towards washes. Lastly additives at nano-scale were added to increase surface roughness in order to obtain higher hydrophobicity and improved of crosslinking capacity due to the presence of more functional groups.  The stability of all emulsions was controlled using different techniques such as optical microscopy to determine particle size, distribution and any observable instability (flocculation etc.), normal aging at room temperature and accelerated aging using higher temperature. All coatings were applied using a laboratory padder on standard PA and PES pieces of textiles and hydrophobic performance was evaluated through ISO 4920 spray test. By standard washing and repeating spray test, durability could be assessed. Further structure and property studies have been run using other tests such as: contact angle measurement, breathability of the coating and SEM observations. Based on the obtained results the incorporation of low HLB, bio-based surfactants in low amount (~0,25%) resulted in an increase in the hydrophobic performance of the tested textiles. However, a decrease in shelf life could be observed with these surfactants at room temperature. Sonication was successfully used to increase both stability and shelf life significantly. Some binders and nanoparticles proved to be successful in increasing the coating quality and thus the durability. Overall many of the developed formulations could enhance performance on PA compared to the already present commercial product. On PES textile, however, the developed strategies yielded hydrophobic effect close to the commercial product.

Limited knowledge exists of the terrain variables that have an influence on gopher tortoise (Gopherus polyphemus) burrow locations. Previous studies suggest that terrain features may play a role in preference of burrow location. LiDAR- (Light Detection and Ranging) derived terrain features can be evaluated through GIS (Geographic Information System) analysis at a fine spatial scale. LiDAR data acquired at 0.5 meter post spacing over three locations on Camp Shelby Joint Forces Training Center, MS were used to develop DTMs (Digital Terrain Models) for use in burrow site characterization. Terrain variables (e.g. elevation, slope, aspect) were developed from the LiDAR DTM in ArcGIS. Burrows and randomly allocated non-burrow points were used in logistic regression analysis to model the relationship between burrow occurrence and terrain features. Four models correctly classified more than 83% of the burrow locations. The R2 were 34.83%, 49.31%, 28.09%, and 31.51%.

The horizontal shear strength of the interface between prestressed concrete hollow core slabs and cast-in-place concrete topping slabs was evaluated through a set of 24 push-off experiments. The push-off test specimens featured segments of dry-mix and wet-mix hollow core slabs with a variety of surface treatments including machine finished, sandblasted, broom roughened, rake roughened and grouted. A cast-in-place slab was poured on top of the hollow core specimens to form a 15 inch by 15 inch interface between the two materials. Results indicate the average horizontal shear strength of the push-off specimens was 227 psi. Higher shear strength and slip capacity was observed in specimens that were broom roughened in the direction transverse to the applied shear force and in grouted dry-mix specimens. Specimens with machine finished surfaces had lower average horizontal shear strength than those with intentionally roughened surfaces, but still exceeded the shear strength of 80 psi specified in the ACI 318-08 code. A method to comparatively quantify the surface roughness of the hollow core slabs with different surface treatments was adapted from an existing ASTM standard for pavements. This standard specifies the procedure to determine mean texture depth that can be correlated to horizontal shear strength of the push-off specimens. Analytical studies were also performed to estimate the maximum horizontal shear stresses that can be expected in composite hollow core slabs under normal construction conditions. A finite element model was developed to observe the behavior of the horizontal shear failure mode for composite hollow core slabs.

<p>This is a dissertation by Funing Li submitted to the Faculty of Purdue University in partial fulfillment of the requirements for the degree of Doctor of Philosophy.</p>

The curing characteristics of photopolymer resin determine the relationship between the vat polymerization (VP) process parameters and the layer thickness, geometric accuracy, and surface quality of the 3D printed specimen. Dispersing filler material into the photopolymer resin changes its curing characteristics because the filler scatters and absorbs light, which modifies the curing reaction. However, the ability to cure photopolymer resin with high filler volume fraction is important to 3D print material specimens for specific engineering applications, e.g. structural polymer composite materials, electrical and thermal conductive materials, and ceramic materials for biological and high-temperature environments. We methodically measure the curing characteristics of diacrylate/epoxy photopolymer resin with dispersed glass microspheres. The experiments show that the curing depth, degree-of-cure, and surface roughness depend on both the light exposure dose and the filler fraction. We determine that the degree-of-cure increases with increasing filler fraction for constant exposure dose, and approaches 90% with increasing exposure dose, independent of the filler fraction. The geometric accuracy of the 3D printed specimens decreases with increasing exposure dose and with increasing filler volume fraction due to so-called profile broadening. Finally, we show that the average surface roughness of the 3D printed specimens decreases with increasing exposure dose and filler fraction. This work has implications for VP of photopolymer resins with high filler fraction. / Master of Science / Photopolymer resin is a gel-like liquid material that hardens (cures) into solid after absorbing light energy, and such a material is often used in the field of additive manufacturing (3D printing) to create complex geometry. Certain types of filler materials, such as metal powder or carbon fiber, can be added into the photopolymer resin to tailor the material properties, and thus, affects the curing behavior of photopolymer resin mixed with these filler materials. We conducted an experiment to understand how adding glass microspheres to a consumer grade photopolymer resin affects the process of creating 3D objects. This is important in the context of 3D printing engineered composite materials that derive their function from the organization and orientation of filler material in a matrix. To do this, we created many samples in the shape of a "VT" logo using the composite resin we made and measured their thickness (curing depth), degree-of-cure, surface roughness, and geometric accuracy, as a function of the amount of light energy being exposed to the resin (exposure dose) and the amount of the glass filler being added into the resin (filler fraction). We observed that when we increased the amount of light exposure, it resulted specimens that are thicker and more in degree of cure. Adding the glass filler to the liquid had mixed effects on the hardening process, because glass can scatter light and change how light travels within the resin. As a result, the printed objects became less accurate in shape and have smoother surface with increasing exposure dose and filler fraction, because more light is scattered off the designed curing profile and unintentionally cured the surrounding resin.

No description available.

No description available.

While cement treatment is a proven method for improving the strength and durability of soils and aggregates, cement hydration causes shrinkage strains in the cement-treated base (CTB) that can lead to reflection cracking in asphalt surfaces. Cracking may then cause increased pavement roughness and lead to poor ride quality. The overall purpose of this research was to utilize data collected through the Long-Term Pavement Performance (LTPP) program to investigate the use and classification of CTB layers and evaluate the relative impact of cement content on the development of roughness and cracking in asphalt concrete (AC) pavements constructed using CTB layers. The data included 52 LTPP test sites, which represented 13 different states and one Canadian province, with cement contents ranging from 3.0 to 9.5 percent by weight of dry aggregate. Statistical procedures were utilized to identify the factors that were most correlated to the observed pavement performance and to develop prediction equations that transportation agencies can use to estimate the amount of roughness for a given pavement at a given age and the amount of distress associated with a particular crack severity level for a given pavement. The data collected for this study suggest that wide ranges of cement contents are used to stabilize soils within individual American Association of State Highway and Transportation Officials soil classifications. The data also suggest that CTBs comprising flexible pavement structures are constructed mainly on rural facilities. A backward-selection model development technique was used to develop sets of prediction equations for roughness and cracking. Age, AC thickness, CTB thickness, and cement content were determined to be significant predictors of International Roughness Index, while age, air freezing index, AC thickness, CTB thickness, cement content, and traffic loads in thousands of equivalent single-axle loads were determined to be significant predictors of low-severity, medium-severity, and high-severity block, fatigue, longitudinal (wheel-path and non-wheel-path), and transverse cracking in AC pavements constructed using CTB layers. Investigation of the relationships between CTB modulus and the development of roughness and cracking is recommended for further study.

During the operation of a gas turbine, ingested contaminants present in the air form deposits on the surfaces of the turbine blades. These deposits grow over time, resulting in an increasingly rough surface. This gradual increase in roughness results in several negative consequences, among which is an increase in the rate of heat transfer to the blade which shortens blade life. This thesis presents research in which deposits were evolved on three different turbine blade coupons and their evolution was studied. A trend in roughness change over time was discovered. Also, an attempt was made to find the effect of the deposits on the heat transfer characteristics of a coupon surface. The deposits were formed using the BYU Turbine Accelerated Deposition Facility (TADF), which was used to simulate three months of deposition within a two hour test time. All three coupons underwent four cycles in the TADF: eight total hours of combustor testing—or one simulated year of deposition—with topological measurements being made on the coupon surface after every two hours (three simulated months) of testing. The data produced by the topological measurements were used with a CNC mill to machine scaled-up plastic models of the rough surfaces: four surfaces per model representing three, six, nine, and twelve simulated months of deposition. The models were placed in a wind tunnel where, following a period of thermal soaking at room temperature, they were suddenly exposed to a heated air stream. The thermal histories of the model were recorded with an infrared camera and were used to derive the heat transfer coefficient of each surface using the method developed by Shultz and Jones. The heat transfer coefficients are reported in the form of Stanton numbers to allow for the difference in thermal properties between the conditions and properties of the wind tunnel and its components and those of a real gas turbine. The Stanton numbers for the various surfaces were plotted versus the simulated gas turbine operational time. Additionally, several roughness correlations were used to predict the Stanton number for each surface, producing a probable Stanton number history for the coupon. The measured nondimensional heat transfer coefficients did not reach the magnitudes predicted by the correlations. This is most likely due to unexpected flow conditions inside the wind tunnel. Recommendations for future research are presented.