Michigan Technological University

About: Michigan Technological University is a education organization based out in Houghton, Michigan, United States. It is known for research contribution in the topics: Population & Volcano. The organization has 8023 authors who have published 17422 publications receiving 481780 citations. The organization is also known as: MTU & Michigan Tech.

The Effect of Fuel and Engine Design on Diesel Exhaust Particle Size Distributions

Abstract: The objective of this research was to obtain diesel particle size distributions from a 1988 and a 1991 diesel engine using three different fuels and two exhaust control technologies (a ceramic particle trap and an oxidation catalytic converter). The particle size distributions from both engines were used to develop models to estimate the composition of the individual size particles. Nucleation theory of the H{sub 2}O and H{sub 2}SO{sub 4} vapor is used to predict when nuclei-mode particles will form in the dilution tunnel. Combining the theory with the experimental data, the conditions necessary in the dilution tunnel for particle formation are predicted. The paper also contains a discussion on the differences between the 1988 and 1991 engine`s particle size distributions. The results indicated that nuclei mode particles (0.0075--0.046 {micro}m) are formed in the dilution tunnel and consist of more than 80% H{sub 2}O-H{sub 2}SO{sub 4} particles when using the 1988 engine and 0.29 wt% sulfur fuel. Nucleation theory indicated that H{sub 2}O-H{sub 2}SO{sub 4} particles may form during dilution at 0.03 wt% fuel sulfur levels and above. The 1991 engine was designed for lower particulate emissions than the 1988 engine and the 1991 engine`s accumulation mode particles (0.046-1.0 {micro}m) weremore » reduced more than 80% by volume compared to the 1988 engine using the same low sulfur fuel. The particle size composition model indicated that using low sulfur fuel and the 1991 engine, the nuclei mode contained more than 45% of the total solid particles and over 85% of the soluble organic fraction.« less

Comparison of methods for determining bulk densities of rocky forest soils

Abstract: Measurement of forest soil bulk density is often hampered by coarse fragments. In this study, five methods to determine total and fine bulk density and coarse-fragment content of a rocky forest soil in western Montana were evaluated. Two methods of core sampling (small and large diameter cylinders), two methods of soil excavation and volume determination (water and polyurethane foam), and a nuclear source moisture gauge were tested at two depths (0-10 cm and 10-20 cm) on a soil with a 35% slope and 45% rock content. In the surface 10 cm, total and fine soil bulk density values were greatest from the nuclear gauge. The two excavation techniques gave similar results. Volumetric rock-fragment content calculations using the small diameter cylinder were significantly lower than those using the other methods. At the 10- to 20-cm depth, all methods except the large diameter cylinder gave comparable results for total soil bulk density. The small diameter core method gave the highest estimate of fine bulk density at this depth. All methods are easy to use. Soil excavation using the polyurethane foam for volume determinations is the simplest method and has low standard errors.

Impulsive responding and the sustained attention to response task.

Abstract: Two studies investigated whether the sustained attention to response task (SART) is a better measure of impulsive responding than of sustained attention. Participants performed target detection tasks with global-local letter stimuli using one of two response formats: standard, responding to targets; and SART, withholding to targets. In the first experiment, performance in the SART changed rapidly over time, whereas performance in the standard format was stable over time. In the second experiment, performance in the SART was susceptible to global-local condensation tasks, a result previously found with highly impulsive individuals. Overall the results indicate that the SART is sensitive to impulsive responding.