Copyright (c) 2009 University of Nebraska - Lincoln All rights reserved. http://digitalcommons.unl.edu/mechengfacpub Recent documents in Mechanical Engineering Faculty Publications en-us Sat, 14 Nov 2009 23:18:01 PST 3600 http://digitalcommons.unl.edu/mechengfacpub/35 http://digitalcommons.unl.edu/mechengfacpub/35 Fri, 13 Nov 2009 12:27:35 PST The present invention provides a micro-robot for use inside the body during minimally-invasive surgery. The microrobot may include various sensors, imaging devices or manipulators. Dmitry Oleynikov http://digitalcommons.unl.edu/mechengfacpub/34 http://digitalcommons.unl.edu/mechengfacpub/34 Fri, 13 Nov 2009 12:22:46 PST The present invention provides a robot for use inside an open abdominal cavity during minimally-invasive surgery. The robot may include various sensors, imaging devices or manipulators. Dmitry Oleynikov http://digitalcommons.unl.edu/mechengfacpub/33 http://digitalcommons.unl.edu/mechengfacpub/33 Fri, 13 Nov 2009 12:09:19 PST An on-board, noncontact measurement system and method is disclosed for measuring track quality, vertical track stiffness and vertical track modulus for a portion of track underlying the rail vehicle. The system comprises first and second optical emitters mounted to the vehicle and configured to emit beams of light that are detectable on the underlying surface; a camera mounted to the vehicle for recording the distance between the beams of light as the vehicle travels along the surface, a mechanism for measuring the distance between the beams of light for a particular portion of the surface; and a mechanism for determining the vertical track stiffness or vertical track modulus for a particular portion of the track. Shane Farritor http://digitalcommons.unl.edu/mechengfacpub/32 http://digitalcommons.unl.edu/mechengfacpub/32 Fri, 13 Nov 2009 12:04:39 PST The present invention is a miniature camera robot which can be placed entirely within an open space such as an abdominal cavity. The instant camera robot has pan and tilt capabilities, an adjustable focus camera, and a support component for supporting the robot body. In particular embodiments, the camera robot further contains a light source for illumination and a handle to position the camera robot. A system and method for using the instant camera robot are also provided. Dmitry Oleynikov http://digitalcommons.unl.edu/mechengfacpub/31 http://digitalcommons.unl.edu/mechengfacpub/31 Fri, 13 Nov 2009 11:53:58 PST A high-impact, energy-absorbing vehicle barrier system generally includes a substantially rigid outer containment wall coupled via strap assemblies with an energy-absorbing inner impact wall, and energy-absorbing cartridges strategically positioned between the impact wall and containment wall. The impact wall is constructed of a number of tubes coupled with one another to present a substantially smooth, unifonn surface to passing vehicles. The energy-absorbing cartridges generally consist of a foam member or a number of foam sheets which compress and crush between the containment wall and impact wall to absorb energy from an errant vehicle striking the face of the impact wall, while the deflection and deformation of the impact wall tubes dissipates additional energy to reduce peak decelerations and mitigate the severity of high-energy vehicular impacts. Internal splice units and the strap assemblies provide for relatively easy and quick replacement of damaged impact wall sections and energyabsorbing cartridges Ronald K. Faller http://digitalcommons.unl.edu/mechengfacpub/30 http://digitalcommons.unl.edu/mechengfacpub/30 Tue, 13 Oct 2009 14:05:32 PDT Extremely fine (<10 μm) Nd-Fe-B powder was generated by pulsed plasma atomization processing. The number average was just over 3 μm, as determined by computer-assisted scanning electron microscopy analysis of almost 3000 particles. Despite the fine particle size, alloys of stoichiometric Nd2Fe14B resulted in the properitectic formation of α-Fe, deleteriously affecting the magnetic properties. Nevertheless, this work shows the possibility of generating extremely fine, isotropic powder for bonded and hybrid magnet applications. Jeffrey E. Shield http://digitalcommons.unl.edu/mechengfacpub/29 http://digitalcommons.unl.edu/mechengfacpub/29 Mon, 12 Oct 2009 11:55:55 PDT The need to understand and quantify the heat transfer paths within tapered-roller bearings is of great importance in the railroad industry since bearing cup temperature measurement is the primary tool utilized in the removal of distressed bearings from service. Experiments were performed to acquire temperature histories at several locations on a stationary bearing subjected to heat sources imbedded in two rollers. The experimental results were compared to zero- and first-order thermal models to estimate overall heat transfer coefficients from the bearing. The results presented here can be used to explain some of the mechanisms that lead to overheating of tapered-roller bearings. Constantine M. Tarawneh http://digitalcommons.unl.edu/mechengfacpub/28 http://digitalcommons.unl.edu/mechengfacpub/28 Tue, 22 Sep 2009 13:20:44 PDT The effect of combined alloying additions on the structure and scale of rapidly solidified Sm-Fe alloys was investigated. Transition metal additions tend to promote the formation of the disordered TbCu7-type structure in Sm2Fe17 alloys, as determined by monitoring the long-range order parameter. Essentially no order was observed for M = Ti, Zr, V, or Nb. Thus, the structure was close to the prototypical TbCu7-type structure. With M = Si, a large amount of order was observed (S = 0.62), resulting in a structure closer to the well-ordered Th2Zn17-type. The microstructural scale was also affected by alloying. In this case, refinement depended on the substituent and also on carbon for microstructural refinement. The scale of the as-solidified grain structures ranged from 100 nm for SiC-modified alloys to 13 nm for NbC-modified alloys. The degree of refinement was directly related to the atomic size of the M addition. The refinement was the result of solute partitioning to grain boundaries, resulting in a solute drag effect that lowered the growth rates. B. E. Meacham http://digitalcommons.unl.edu/mechengfacpub/27 http://digitalcommons.unl.edu/mechengfacpub/27 Tue, 22 Sep 2009 13:17:07 PDT X-ray diffraction from a synchrotron source was employed in an attempt to identify the crystal structures in zirconia ceramics produced by the sol-gel method. The particles of chemically precipitated zirconia, after calcination below 600 °C, are very fine, and have a diffracting particle size in the range of 7-15 nm. As the tetragonal and cubic structures of zirconia have similar lattice parameters, it is difficult to distinguish between the two. The tetragonal structure can be identified only by the characteristic splittings of the Bragg profiles from the "c" index planes. However, these split Bragg peaks from the tetragonal phase in zirconia overlap with one another due to particle size broadening. In order to distinguish between the tetragonal and cubic structures of zirconia, three samples were studied using synchrotron radiation source. The results indicated that a sample containing 13 mol % yttria-stabilized zirconia possessed the cubic structure with ao -- 0.51420 ± 0.00012 nm. A sample containing 6.5 mol % yttria stabilized zirconia was found to consist of a cubic phase with ao -- 0.51430 ± 0.00008 nm. Finally, a sample which was precipitated from a pH 13.5 solution was observed to have the tetragonal structure with ao = 0.51441 ± 0.00085 nm and co = 0.51902 ± 0.00086. Ram Srinivasan http://digitalcommons.unl.edu/mechengfacpub/25 http://digitalcommons.unl.edu/mechengfacpub/25 Mon, 10 Aug 2009 10:09:06 PDT Exact solutions are given for the transient temperature in flux-base fins with the method of Green's functions (GF) in the form of infinite series for three different tip conditions. The speed of convergence is improved by replacing the steady part by a closed-form steady solution. For the insulated-tip case, a quasi-steady solution is presented. Numerical values are presented and the conditions under which the quasi-steady solution is accurate are determined. An experimental example is given for estimation of the heat transfer coefficient (HTC) on a non-rotating roller bearing, in which the outer bearing race is treated as a transient fin. Kevin D. Cole