Thesis (M.S. in environmental engineering)--Washington State University, December 2009. / Title from PDF title page (viewed on Jan. 15, 2010). "Department of Civil and Environmental Engineering." Includes bibliographical references (p. 32-34).

Thesis (M.D.S.)--University of Hong Kong, 2001. / Includes bibliographical references (leaves 112-129).

Thesis (doctoral)--Aalto University, 2010. / Includes bibliographical references. Also available on the World Wide Web.

Thesis (doktor-ingenieur)--Technische hochschule, Stuttgart. / Lebenslauf. "Literaturverzeichnis": p. 7-8.

Thesis (M.S.)--West Virginia University, 2001. / Title from document title page. Document formatted into pages; contains x, 92 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 79-83).

Thesis (M. Sc.)--University of Hong Kong, 1960. / Mimeographed. Includes bibliographical references (p. 71-74).

Thesis--M. Sc.(Eng.), University of Hong Kong. / Mimeographed.

published_or_final_version / Dentistry / Doctoral / Doctor of Philosophy

The production of high-performance concrete having all-rounded high performance has been promoted for the last few decades. Meanwhile, environmental concerns have quested for minimizing cement consumption to reduce carbon footprint. However, contradictory requirements are often imposed on the mix parameters in order to satisfy all the required performance attributes and environmental limitations. The addition of inert fillers such as limestone fines (LF) is a promising way to overcome these difficulties. In this thesis, the packing density and overall performance of mortar and concrete containing different amounts of LF are investigated. The test results revealed that blending of fine aggregate with LF or with both LF and cement could significantly increase the packing density because the LF and cement particles are much smaller than the aggregate particles and are thus able to fill into the voids between the aggregate particles. However, LF with similar fineness as cement has no filling effect for increasing the packing density when added to cement to a mortar mix in which the powder content is already enough to fill the voids between aggregate particles. Its filling effect is contributed mainly by filling into the paste to increase the paste volume. In fact, the addition of LF to mortar would slightly decrease the packing density, significantly decrease the water film thickness (WFT) and significantly increase the paste film thickness (PFT). The actual effects of LF volume on the packing density, WFT and PFT are dependent on the cement paste volume. In-depth analysis of the test results showed that the apparently complicated effects of the LF volume are caused by the corresponding changes in the WFT and PFT of the mortar. The overall effects of LF are dependent on the net outcome of the decrease in WFT and the increase in PFT due to the addition of LF. The addition of LF would increase the flow spread when the WFT is relatively large as the decrease in WFT has smaller effect than the increase in PFT, increase the cohesiveness when the LF volume is relatively small as the decrease in WFT has greater effect and increase the early strength provided the WFT would not become too small. However, the addition of LF would always decrease the flow rate because the decrease in WFT always has greater effect than the increase in PFT. Finally, the possible use of LF as cement paste replacement to reduce cement paste volume is studied. From the correlation of the ultimate shrinkage strain to the cement paste volume and W/C ratio, and to the concrete strength and cement paste volume, it may be concluded that cement paste replacement by the addition of LF would reduce the shrinkage of concrete by both decreasing the cement paste volume and increasing the concrete strength. Moreover, since the reduction in cement paste volume would allow less cement to be used, this would also lead to the production of concrete more ecological. More research on this possible usage of various inert fillers with different fineness is recommended. / published_or_final_version / Civil Engineering / Master / Master of Philosophy

Motor unit synchronization is phenomenon driven by a common input that results in the near-simultaneous firing of two or more motor units, which is referred to as short-term synchronization. The relationship between motor unit synchronization and force steadiness is still unclear, even after numerous experiments and simulations. Our main hypothesis was that the decreased force tetanus brought on by motor unit synchronization would be correlated to reduced steadiness at very low hand muscle forces. To determine if this correlation existed, young, healthy adults performed a submaximal, isometric pinch at four forces to determine if motor unit synchronization increased with a progressive decrease in force steadiness driven by reduced force levels. However, before performing synchronization analyses, we had to establish the best technique for measuring motor unit coherence, which quantifies the strength and frequency of a periodic common input. We used a pool of simulated spike trains with various firing rates, coefficients of variation (CV), common input frequencies and trial durations to explore the effects of data segmentation and spike train properties on coherence. We found that tapered segments overlapped by at least 50% maximized coherence measurements, regardless of taper type and that increasing common input frequency CV from 0.15-0.50 made coherence measurements unusable, even at high synchronization levels. During an isometric pinch at 2, 4, 8, and 12% of maximum digit force, we recorded thumb and index finger forces and EMG from the first dorsal interosseous (FDI) and adductor pollicis (AdP) muscles. As expected, the force CV dropped as each digit force increased. Pooled coherence revealed a dominant peak for the 2-10 Hz, but power for both digits' forces was limited to the 0-2 Hz bandwidth. There was a weak correlation for thumb force CV and coherence for within-AdP pairs, but no significant correlations were found for within-FDI pair coherence and finger force CV. Therefore, motor unit synchronization was not a strong driver of force steadiness for this protocol. To ensure that inherent firing rate nonstationarity of spike train data did not affect coherence measurements, we produced a new set of spike train pairs with firing rates and variances that approximated those for physiological motor units, which varied from 0-25%. Stationarity level was not significantly correlated to peak coherence (max R² = 0.082). Therefore, coherence measurements of spike train data with characteristics similar to those of the simulated trains were not significantly affected by nonstationarity. The establishment of the best method for computing coherence, the lack of a strong correlation between force steadiness and motor unit synchronization for submaximal isometric forces, and the knowledge that spike train nonstationarity has no significant effect on coherence measurements are all important discoveries needed for progress in the areas of basic neuromuscular function, motor unit synchronization, and pathological force unsteadiness.