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.

Bond Performance between Ultrahigh-Performance Concrete and Normal-Strength Concrete

Abstract: Ultrahigh-performance concrete (UHPC) exhibits several properties that make it appropriate for the rehabilitation of concrete structures. In this investigation, the application is focused on bridge deck overlays, but the study is equally applicable to other rehabilitation applications. Its negligible permeability makes this material suitable as a protective barrier that prevents any water or chemical penetration into the substrate. In addition, its ultra-high compressive strength and post-cracking tensile capacity could provide an improvement to the bearing capacity. However, for extensive acceptance, it has to be demonstrated that the bond between UHPC and normal strength concrete (NSC) offers a good long-term performance under a variety of operating conditions. The UHPC-NSC interface can experience high tensile, shear, and compressive stresses at both early and later life stages and the environmental conditions inherent to the operating environment. The success of the rehabilitation will depend ...

Characterization of uniaxial compressive response of bulk amorphous Zr–Ti–Cu–Ni–Be alloy

Abstract: Uniaxial compressive response of bulk amorphous Zr–Ti–Cu–Ni–Be alloy, also called as Vitreloy-1, was investigated at quasistatic and high strain rates in the range of 10−3 and 103 s−1, respectively. The Vitreloy-1 specimens exhibited elastic response followed by catastrophic fracture along a narrow shear band. The ultimate strength of the specimens varied between 1800 and 2200 MPa irrespective of the strain rate and independent of the aspect ratio of the specimens. The quasistatically deformed specimens fractured into two or three large fragments. The fracture surfaces were relatively smooth and revealed well developed and uniformly distributed veinal pattern. The dynamically loaded specimens, on the other hand, fractured into several fragments with relatively rough fracture surfaces containing nonuniformly distributed and partially developed veinal patterns. Evidence of melting in the form of ‘liquid bubbles’ was also observed along the cracks on the fracture surfaces of the specimens subjected to high strain-rate loading. A comparison of the mechanical response of Vitreloy-1 with other bulk metallic glass systems is also presented.

Organic matter pathways to zooplankton and benthos under pack ice in late winter and open water in late summer in the north-central Bering Sea

Abstract: On continental shelves in arctic and subarctic seas, much of the production from spring blooms at the retreating ice edge may sink to the bottom with little grazing by zooplankton, thereby supporting abundant benthic communities. The importance of this settled phytoplankton to mac- robenthos throughout the year may partly determine effects of long-term changes in ice cover. We studied organic matter (OM) pathways to macrobenthos and macrozooplankton under ice cover in late winter (March-April) and open water in late summer (September) in the north-central Bering Sea. In late winter 2001, only a very small fraction of OM in the water column was particulate. C:N ratios, δ 13 C, and δ 15 N in suspended particulate organic matter (SPOM), and sediments indicated very little recent input of fresh ice algae or phytoplankton in ice-covered areas. For the 3 main deposit- feeding bivalves, δ 13 C and δ 15 N indicated similar diets among species, with minimal change in food quality between late summer and late winter, and between late winters with very different ice cover (1999 vs. 2001). In winter 2001, there were large increases in δ 13 C from SPOM to bulk sediments (+3.2‰) and from sediments to near-surface deposit-feeders (+1.6 to +3.0‰), but small differences in δ 15 N from SPOM to sediments (+1.2‰) and from sediments to deposit-feeders (-0.3 to +1.6‰). These values suggest that the diet of near-surface deposit-feeders during these non-bloom periods included substantial amounts of the cells or products of bacteria that had assimilated well-reworked carbon and isotopically light dissolved inorganic nitrogen (DIN). By late summer and through winter, 4 to 11 mo after the spring bloom, products of bacterial activity appeared to be an important route of OM into the benthic food web. Due to bacterial dependence on annual carbon inputs, and unique nutrient content of fresh phytoplankton for breeding invertebrates, ice-edge blooms might be an important determinant of annual variations in macrobenthic abundance.

Giant piezoelectric voltage coefficient in grain-oriented modified PbTiO 3 material

Abstract: A rapid surge in the research on piezoelectric sensors is occurring with the arrival of the Internet of Things. Single-phase oxide piezoelectric materials with giant piezoelectric voltage coefficient (g, induced voltage under applied stress) and high Curie temperature (Tc) are crucial towards providing desired performance for sensing, especially under harsh environmental conditions. Here, we report a grain-oriented (with 95% texture) modified PbTiO3 ceramic that has a high Tc (364 °C) and an extremely large g33 (115 × 10-3 Vm N-1) in comparison with other known single-phase oxide materials. Our results reveal that self-polarization due to grain orientation along the spontaneous polarization direction plays an important role in achieving large piezoelectric response in a domain motion-confined material. The phase field simulations confirm that the large piezoelectric voltage coefficient g33 originates from maximized piezoelectric strain coefficient d33 and minimized dielectric permittivity ɛ33 in [001]-textured PbTiO3 ceramics where domain wall motions are absent.