This study is comprised of three major parts. The first part involved the development of a multi-measurement, confined, free-free resonant column device. This device was developed to improve upon traditional manually excited, vacuum-confined, free-free methods. The device is capable of testing specimens with diameters up to 6-in., under confinements upwards of 50 psi. The device is composed of a seismic-source system, a data acquisition system and a specimen support and confinement system. The seismic source system is used to induce small-strain constrained compression waves, and longitudinal and torsional stress waves in the specimen. The data acquisition system is used to measure: (1) direct travel time of constrained compression waves, (2) longitudinal resonance in unconstrained compression, and (3) torsional resonance. From these measurements, constrained compression wave velocity, Vp, unconstrained compression wave velocity, Vc, and shear wave velocity, Vs, can be determined. With these wave velocities, small-strain, constrained modulus, Mmax, Young’s modulus, Emax, and shear modulus, Gmax can be determined. Poisson’s ratio is also calculated with the wave velocities. Finally, from the resonance measurements, small-strain material damping in unconstrained compression, DCmin, and in shear, DSmin, can be evaluated. The second part of this study involved verification tests with materials of known dynamic properties. The tests were performed with a manufactured aluminum specimen, ASTM graded Ottawa sand, and crushed rock aggregate base. The results compared well with previous results from similar tests. The third part of this study involved testing artificially cemented ASTM graded Ottawa sand. Cement contents (by weight) of 0.0, 0.5, 1.0 and 2.0%, were used to observe the effect of cementation with curing time at a constant confining pressure of 5 psi. The overall effect of cementation was: (1) a large increase in stiffness, and (2) an increase in material damping. The key effects related to cementation versus curing time are: (1) the increase in wave velocities are reasonably proportional to an increase in cement content up to a curing time of about 5 to 7 days, and (2) after a curing time of 5 to 7 days time the velocity increase with time seems to be similar for all cemented specimens. Additionally, the 2% cemented specimen was tested to observe the effect of confining pressure. The stiffness of this specimen was quite insensitive to confining pressure as was the material damping. / text

Several free-free beam micro-resonators are designed and fabricated using two commercially available surface micromachining processes, the UW-MEMS process and PolyMUMPs. Theoretical derivations of the design parameters are presented and an electrical lumped behavior model is developed for a single resonator with direct mechanic-to-electric analogy. A finite-element analysis (FEA) tool, the COMSOL Multiphysics 4.2a, is utilized to simulate the effects of the critical structural dimensions and electromechanical coupling. A variety of analyses, such as modal, static and dynamic responses are performed in FEA and the results are compared with the analytical solutions. The static and dynamic performances of the fabricated UW-MEMS resonators are tested using the Vecco NT-9100 In-Motion System. The electrical testing is carried out to obtain the frequency characteristics in electrical domain of the device. Measured data are compared with the analytical and simulation results. Discrepancies are discussed and analyzed.

In dense hot star winds, the infrared and radio continua are dominated by free‐free opacity and recombination emission line spectra. In the case of a spherically symmetric outflow that is isothermal and expanding at constant radial speed, the radiative transfer for the continuum emission from a dense wind is analytic. Even the emission profile shape for a recombination line can be derived. Key to these derivations is that the opacity scales with only the square of the density. These results are well‐known. Here an extension of the derivation is developed that also allows for line blends and the inclusion of an additional power‐law dependence beyond just the density dependence. The additional power‐law is promoted as a representation of a radius dependent clumping factor. It is shown that differences in the line widths and equivalent widths of the emission lines depend on the steepness of the clumping power‐law. Assuming relative level populations in LTE in the upper levels of He II, an illustrative application of the model to Spitzer/IRS spectral data of the carbon‐rich star WR 90 is given (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Reuse of reclaimed asphalt pavement (RAP) in the full-depth recycling (FDR) process is a cost-effective and environmentally responsible method of asphalt pavement reconstruction. Although FDR has been used for several years in some locations, the effect of RAP on the mechanical properties of recycled base materials has not been well documented. The purpose of this research was to investigate the influence of RAP on the mechanical properties of recycled base materials typical of northern Utah. Two sources of RAP, two sources of base, and RAP contents of 0, 25, 50, 75, and 100 percent were utilized in a full-factorial experimental design with three replicates of each unique combination. Testing procedures consisted of material classifications, compaction tests, and evaluations of strength, stiffness, and moisture susceptibility of each material blend. The California bearing ratio (CBR) test was used to measure strength, the free-free resonant column test was used to measure stiffness, and the tube suction test (TST) was used to measure moisture susceptibility. Once all the testing was completed, a fixed effects analysis of variance (ANOVA) was performed on each of the test results, or dependent variables. The independent variables were RAP content, RAP type, and base type, together with all their interactions. Results of the ANOVA were used to quantify the effects of RAP on the mechanical properties of the base materials. The data indicate that CBR values decrease as RAP content increases, with the greatest percentage reduction occurring with the addition of 25 percent RAP. For stiffness testing at the optimum moisture content determined for each blend, the general trend was a decrease in stiffness from 0 percent RAP to 25 percent RAP, followed by a steady increase in stiffness as the RAP content was increased from 25 to 100 percent. Following a 72-hr drying period at 140ºF, however, the general trend reversed; an increase in stiffness occurred as the RAP content was increased from 0 to 25 percent, and a steady decrease in stiffness was observed for RAP contents above 25 percent. The TST data suggest that additions of 25 and 50 percent RAP actually increase the moisture susceptibility of the recycled material compared to the neat base, although the blended material tested in this study was classified as non-moisture-susceptible when the RAP content was 75 percent or higher. Because of the marked impact of RAP content on the mechanical properties of recycled base materials, engineers should accurately determine asphalt layer thicknesses prior to pavement reconstruction and carefully determine the optimum blending depth for each project. While asphalt milling or base overlays may be required in some locations to avoid excessively high RAP contents, reduced blending depths may be warranted in other areas to prevent the use of low RAP contents. In summary, while the use of RAP in the FDR process is environmentally responsible and offers potentially significant cost savings, thicker pavement base layers, base stabilization, or both may be required in many instances to ensure adequate long-term pavement performance.