Pure Water Jet Machining of Ti-6Al-4V and Al 6061-T6 at Small Scales

This study investigates the use of ABAQUS's Smoothed Particle Hydrodynamics to simulate pure water jet machining of Al 6061-T6 and Ti-6Al-4V and further examines the ability to machine the same materials using a pulsed water jet using ABAQUS Smoothed Particle Hydrodynamics (SPH) at the same pressure and orifice diameters. These simulations were then verified experimentally at two pressures, 138 MPa and 317 MPa. Predictive modeling was also conducted using the two additional pressures 400 MPa and 621 MPa as well as three orifice diameters 0.254 mm, 0.3556 mm, and 0.4572 mm. Aluminum was chosen due to its low density and its ability to resist corrosion through passivation, and its importance to the aerospace industry, transportation, and building industries. Titanium was chosen because of the difficulties machining Titanium using conventional machining methods. Common problems when machining titanium using traditional metal cutting processes include tools that rapidly wear out and need to be replaced and poor machined surface integrity. The techniques developed in this study allow high precision machining of titanium that preserves the integrity of the machined material, reduces tool wear or even eliminates tooling entirely. The Al 6061-T6 simulations were validated at both pressures and had a percent error of less than 3% and were within the standard deviation of the experimental results. For the Ti-6Al-4V, simulations were validated at both pressures and had a percent error of less than a 2.6% and were within the standard deviation of the experimental results

The large-scale soil box: A new device for testing the performance of buried pipe

A new apparatus that measures pipe deflection as a function of simulated overburden stress is described†the large-scale soil box (LSSB). While the LSSB is similar to previous quasi-full scale instruments, it is capable of load testing two pipes simultaneously while monitoring deflection along their crowns. A series of tests were conducted on 24 and 36-in., 10-ft-long pipe sections. Pipe material varied throughout testing; materials included polyvinylchloride (PVC), high-density polyethylene (HDPE), steel, and aluminum. During load application, lasers allowed for deflection curves to be developed for each of the pipes as a function of simulated overburden produced via constrained lift bags. Analysis of the results appeared to indicate that loading in the LSSB is not necessarily uniform. This is likely due to non-uniform soil densities that were present prior to testing even though strict procedures and quality control checks were used prior to each test. Therefore, it would be difficult to use data from a device like this as a comparison against finite element models. However, results from these tests still may be used to assess the relative levels of effect of different pipe types and installation procedures

The Large-Scale Soil Box: A New Device for Testing the Performance of Buried Pipe

A new apparatus that measures pipe deflection as a function of simulated overburden stress is described†the large-scale soil box (LSSB). While the LSSB is similar to previous quasi-full scale instruments, it is capable of load testing two pipes simultaneously while monitoring deflection along their crowns. A series of tests were conducted on 24 and 36-in., 10-ft-long pipe sections. Pipe material varied throughout testing; materials included polyvinylchloride (PVC), high-density polyethylene (HDPE), steel, and aluminum. During load application, lasers allowed for deflection curves to be developed for each of the pipes as a function of simulated overburden produced via constrained lift bags. Analysis of the results appeared to indicate that loading in the LSSB is not necessarily uniform. This is likely due to non-uniform soil densities that were present prior to testing even though strict procedures and quality control checks were used prior to each test. Therefore, it would be difficult to use data from a device like this as a comparison against finite element models. However, results from these tests still may be used to assess the relative levels of effect of different pipe types and installation procedures

Quantitative DNA Analyses for Airborne Birch Pollen

Birch trees produce large amounts of highly allergenic pollen grains that are distributed by wind and impact human health by causing seasonal hay fever, pollen-related asthma, and other allergic diseases. Traditionally, pollen forecasts are based on conventional microscopic counting techniques that are labor-intensive and limited in the reliable identification of species. Molecular biological techniques provide an alternative approach that is less labor-intensive and enables identification of any species by its genetic fingerprint. A particularly promising method is quantitative Real-Time polymerase chain reaction (qPCR), which can be used to determine the number of DNA copies and thus pollen grains in air filter samples. During the birch pollination season in 2010 in Mainz, Germany, we collected air filter samples of fine (<3 mu m) and coarse air particulate matter. These were analyzed by qPCR using two different primer pairs: one for a single-copy gene (BP8) and the other for a multi-copy gene (ITS). The BP8 gene was better suitable for reliable qPCR results, and the qPCR results obtained for coarse particulate matter were well correlated with the birch pollen forecasting results of the regional air quality model COSMO-ART. As expected due to the size of birch pollen grains (similar to 23 mu m), the concentration of DNA in fine particulate matter was lower than in the coarse particle fraction. For the ITS region the factor was 64, while for the single-copy gene BP8 only 51. The possible presence of so-called sub-pollen particles in the fine particle fraction is, however, interesting even in low concentrations. These particles are known to be highly allergenic, reach deep into airways and cause often severe health problems. In conclusion, the results of this exploratory study open up the possibility of predicting and quantifying the pollen concentration in the atmosphere more precisely in the future