Engineering Commons^™

Horses Damp The Spring In Their Step, Alan M. Wilson, M. Polly Mcguigan, Anne Su, Antonie J. Van Den Bogert

Mechanical Engineering Faculty Publications

The muscular work of galloping in horses is halved by storing and returning elastic strain energy in spring-like muscle–tendon units^{1, 2}.These make the legs act like a child's pogo stick that is tuned to stretch and recoil at 2.5 strides per second. This mechanism is optimized by unique musculoskeletal adaptations: the digital flexor muscles have extremely short fibres and significant passive properties, whereas the tendons are very long and span several joints^{3, 4}. Length change occurs by a stretching of the spring-like digital flexor tendons rather than through energetically expensive length changes in the muscle^{5 …}

Distributed Fault Tolerance In Optimal Interpolative Nets, Daniel J. Simon

Electrical and Computer Engineering Faculty Publications

The recursive training algorithm for the optimal interpolative (OI) classification network is extended to include distributed fault tolerance. The conventional OI Net learning algorithm leads to network weights that are nonoptimally distributed (in the sense of fault tolerance). Fault tolerance is becoming an increasingly important factor in hardware implementations of neural networks. But fault tolerance is often taken for granted in neural networks rather than being explicitly accounted for in the architecture or learning algorithm. In addition, when fault tolerance is considered, it is often accounted for using an unrealistic fault model (e.g., neurons that are stuck on or off …

2001 Scholars And Artists Bibliography, Michael Schwartz Library, Cleveland State University, Friends Of The Michael Schwartz Library

Scholars and Artists Bibliographies

This bibliography was created for the annual Friends of the Michael Schwartz Library Scholars and Artists Reception, recognizing scholarly and creative achievements of Cleveland State University faculty, staff and emeriti

Dsp-Based Field-Oriented Step Motor Control, Daniel J. Simon, Dennis L. Feucht

Electrical and Computer Engineering Faculty Publications

The SMC3 motor drive has been built using an Analog Devices ADSP-2101 digital signal processor (DSP). The SMC3 is designed to work with two-phase step motors, which are permanent magnet motors with many (typically 100) poles. The firmware in the SMC3 DSP drives the step motor phase windings using field-oriented control rather than using single steps. This method derives the maximum theoretical performance from the motor. This paper describes field-oriented control, and how the SMC3 hardware and firmware implements it.

Modal Uncoupling Of Damped Gyroscopic Systems, Jerzy T. Sawicki, G. Genta

Mechanical Engineering Faculty Publications

A new approach for uncoupling the equations of motion typical for rotordynamical systems is presented. The method does not neglect the speed-dependent e!ects, such as gyroscopic e!ects, and can be particularly valuable in the controller design of actively controlled rotors. In the presence of hysteretic type of damping, the resulting uncoupled gyroscopic systems come with an equivalent viscous damping, equivalent in a sense of yielding the same natural frequency and decay rate. The approach is illustrated through three examples of technical interest: a Je!cott rotor with hysteretic damping, a Stodola}Green rotor, and a rotor of a small gas turbine. The …

Lessons From Roman Cement And Concrete, Norbert J. Delatte

Civil and Environmental Engineering Faculty Publications

Although masonry and lime mortars had been used for centuries by earlier civilizations, the Romans were the first to extensively use naturally occurring volcanic earth to make hydraulic cement. The volcanic powder named “pulvis puteolanis,” found near the town of Puteoli near Naples (now Pozzouli), was used to build magnificent structures. The use of this hydraulic cement in masonry and concrete greatly expanded civil engineering possibilities. The Roman engineer Vitruvius, writing in The Ten Books on Architecture, described the careful materials selection, proportioning, and workmanship that was critical to the performance of Roman concrete. Masonry and coarse and fine …

A Numerical Model For The Cyclic Instability Of Thermally Grown Oxides In Thermal Barrier Systems, Anette M. Karlsson, A. G. Evans

Mechanical Engineering Faculty Publications

Morphological instability of the thermally grown oxide (TGO) is a fundamental source of failure in some thermal barrier systems. The instabilities occur when initial non-planarity in the TGO grows in amplitude as the system experiences thermal cycling. By numerical means, this study explores how these instabilities are linked to constituent properties. The associated phenomena involve oxidation of the TGO, plastic flow of the bond coat, thermal expansion misfit between the TGO, bond coat and substrate, and stress relaxation in the TGO at high temperature. A key implication of the simulations is that the incidence of reverse yielding upon reheating differentiates …

In-Vivo 3d Motion Estimation Of The Shoulder Joint Utilizing Magnetic Resonance Imaging During A Simulated Push Task, D. M. Magnusson, Antonie J. Van Den Bogert, J. L. Ronsky

Antonie J. van den Bogert

No abstract provided.

Molecular Simulation Of Adsorption: Gibbs Dividing Surface And Comparison With Experiment, Orhan Talu, Alan L. Myers

Chemical & Biomedical Engineering Faculty Publications

At low temperature near the normal boiling point, computer simulations of adsorption of gases can be compared directly with experiment. However, for adsorptive gas separations in which the gas is adsorbed near or above its critical temperature, absolute simulation variables must be converted to excess variables for comparison with experiment. The conversion of absolute to excess variables requires the helium pore volume of the adsorbent. Lennard-Jones potential parameters for helium gas molecules interacting with the oxygen atoms of silicalite are ε/k = 28.0 K and σ = 2.952 Å. The helium pore volume of silicalite is 0.175 cm …

Wear And Friction Behavior Of Pressure Infiltration Cast Copper-Carbon Composites, G. Göller, D. P. Koty, M. Singh, A. Tekin

Chemical & Biomedical Engineering Faculty Publications

Metal matrix composites, prepared by pressure infiltration casting of copper base alloy into 2 types of microporous carbon preforms, one with 100% amorphous carbon and the other containing 40 wt pct. graphite and 60 wt pct. amorphous carbon, have been examined for their wear and friction behavior under ambient conditions using a pin-on-plate reciprocating wear tester. Micro-structural characterization of tribo-surfaces has been carried out. The thin carbon films formed on the tribo-surface reduced the friction coefficient and wear for the composites, especially at low loads on the pin. Adhesive wear observed on the tribo-surface promoted wear and …

Modeling Nonlinear Behavior In A Piezoelectric Actuator, Hanz Richter, Eduardo A. Misawa, D. A. Lucca, H. Lu

Mechanical Engineering Faculty Publications

A piezoelectric tube actuator is employed as a sample positioning device in Nanocut, a cutting instrument conceived to study the mechanics of nanometric cutting. Extension of functionality of the instrument as a nanometric machine tool motivates the search for an accurate model of the actuator for implementing feedback control. A simple nonlinear model describing longitudinal expansion of the piezoelectric tube actuator is presented in this paper. The model derivation is based on a non-formal analogy with nonlinear viscoelastic materials under uniaxial extension, for which the responses to a step input are similar to the piezoelectric tube. Suitability of the …

In Vivo Flow Dynamics Of The Total Cavopulmonary Connection From Three-Dimensional Multislice Magnetic Resonance Imaging, Shiva Sharma, Ann E. Ensley, Katherine Hopkins, George P. Chatzimavroudis, Timothy M. Healy, Vincent K.H. Tam, Kirk R. Kanter, Ajit P. Yoganathan

Chemical & Biomedical Engineering Faculty Publications

Background. The total cavopulmonary connection (TCPC) design continues to be refined on the basis of flow analysis at the connection site. These refinements are of importance for myocardial energy conservation in the univentricular supported circulation. In vivo magnetic resonance phase contrast imaging provides semiquantitative flow visualization information. The purpose of this study was to understand the in vivo TCPC flow characteristics obtained by magnetic resonance phase contrast imaging and compare the results with our previous in vitro TCPC flow experiments in an effort to further refine TCPC surgical design.

Methods. Twelve patients with TCPC underwent sedated three-dimensional, multislice …

Another Look At Hartford Civic Center Coliseum Collapse, Rachel Martin, Norbert J. Delatte

Civil and Environmental Engineering Faculty Publications

Only a few hours after five thousand basketball fans had left, the roof of the Hartford Civic Center Coliseum collapsed under a heavy snowfall. Fortunately, the arena was empty. The design of the space frame roof had been based on an innovative and extensive computer analysis. However, when deflections twice as great as those predicted by the computer analysis were observed during construction, the warning was ignored. Overconfidence in computer analysis results played a large part in this failure. A useful lesson from this case is that the computer is only an analytical tool and computed results must be checked …

Evaluation Of The Precision Of Magnetic Resonance Phase Velocity Mapping For Blood Flow Measurements, George P. Chatzimavroudis, John N. Oshinski, Robert H. Franch, Peter G. Walker, Ajit P. Yoganathan, Roderic I. Pettigrew

Chemical & Biomedical Engineering Faculty Publications

Evaluating the in vivo accuracy of magnetic resonance phase velocity mapping (PVM) is not straightforward because of the absence of a validated clinical flow quantification technique. The aim of this study was to evaluate PVM by investigating its precision, both in vitro and in vivo, in a 1.5 Tesla scanner. In the former case, steady and pulsatile flow experiments were conducted using an aortic model under a variety of flow conditions (steady: 0.1–5.5 L/min; pulsatile: 10–75 mL/cycle). In the latter case, PVM measurements were taken in the ascending aorta of ten subjects, seven of which had aortic regurgitation. Each velocity …