Direct load monitoring of rolling bearing contacts using ultrasonic time of flight

The load applied by each rolling element on a bearing raceway controls friction, wear and service life. It is possible to infer bearing load from load cells or strain gauges on the shaft or bearing housing. However, this is not always simply and uniquely related to the real load transmitted by rolling elements directly to the raceway. Firstly, the load sharing between rolling elements in the raceway is statically indeterminate, and secondly, in a machine with non-steady loading, the load path is complex and highly transient being subject to the dynamic behaviour of the transmission system. This study describes a method to measure the load transmitted directly by a rolling element to the raceway by using the time of flight (ToF) of a reflected ultrasonic pulse. A piezoelectric sensor was permanently bonded onto the bore surface of the inner raceway of a cylindrical roller bearing. The ToF of an ultrasonic pulse from the sensor to the roller-raceway contact was measured. This ToF depends on the speed of the wave and the thickness of the raceway. The speed of an ultrasonic wave changes with the state of the stress, known as the acoustoelastic effect. The thickness of the material varies when deflection occurs as the contacting surfaces are subjected to load. In addition, the contact stiffness changes the phase of the reflected signal and in simple peak-to-peak measurement, this appears as a change in the ToF. In this work, the Hilbert transform was used to remove this contact dependent phase shift. Experiments have been performed on both a model line contact and a single row cylindrical roller bearing from the planet gear of a wind turbine epicyclic gearbox. The change in ToF under different bearing loads was recorded and used to determine the deflection of the raceway. This was then related to the bearing load using a simple elastic contact model. Measured load from the ultrasonic reflection was compared with the applied bearing load with good agreement. The technique shows promise as an effective method for load monitoring in real-world bearing applications

Fission stories: using PomBase to understand Schizosaccharomyces pombe biology

PomBase (www.pombase.org), the model organism database (MOD) for the fission yeast Schizosaccharomyces pombe, supports research within and beyond the S. pombe community by integrating and presenting genetic, molecular, and cell biological knowledge into intuitive displays and comprehensive data collections. With new content, novel query capabilities, and biologist-friendly data summaries and visualization, PomBase also drives innovation in the MOD community

Mononuclear phenolate diamine zinc hydride complexes and their Reactions with CO2

[Image: see text] The synthesis, characterization, and zinc coordination chemistry of the three proligands 2-tert-butyl-4-[tert-butyl (1)/methoxy (2)/nitro (3)]-6-{[(2′-dimethylaminoethyl)methylamino]methyl}phenol are described. Each of the ligands was reacted with diethylzinc to yield zinc ethyl complexes 4–6; these complexes were subsequently reacted with phenylsilanol to yield zinc siloxide complexes 7–9. Finally, the zinc siloxide complexes were reacted with phenylsilane to produce the three new zinc hydride complexes 10–12. The new complexes 4–12 have been fully characterized by NMR spectroscopy, mass spectrometry, and elemental analyses. The structures of the zinc hydride complexes have been probed using VT-NMR spectroscopy and X-ray diffraction experiments. These data indicate that the complexes exhibit mononuclear structures at 298 K, both in the solid state and in solution (d(8)-toluene). At 203 K, the NMR signals broaden, consistent with an equilibrium between the mononuclear and dinuclear bis(μ-hydrido) complexes. All three zinc hydride complexes react rapidly and quantitatively with carbon dioxide, at 298 K and 1 bar of pressure over 20 min, to form the new zinc formate complexes 13–15. The zinc formate complexes have been analyzed by NMR spectroscopy and VT-NMR studies, which reveal a temperature-dependent monomer–dimer equilibrium that is dominated by the mononuclear species at 298 K

Superficial simplicity of the 2010 El Mayor–Cucapah earthquake of Baja California in Mexico

The geometry of faults is usually thought to be more complicated at the surface than at depth and to control the initiation, propagation and arrest of seismic ruptures. The fault system that runs from southern California into Mexico is a simple strike-slip boundary: the west side of California and Mexico moves northwards with respect to the east. However, the M_w 7.2 2010 El Mayor–Cucapah earthquake on this fault system produced a pattern of seismic waves that indicates a far more complex source than slip on a planar strike-slip fault. Here we use geodetic, remote-sensing and seismological data to reconstruct the fault geometry and history of slip during this earthquake. We find that the earthquake produced a straight 120-km-long fault trace that cut through the Cucapah mountain range and across the Colorado River delta. However, at depth, the fault is made up of two different segments connected by a small extensional fault. Both segments strike N130° E, but dip in opposite directions. The earthquake was initiated on the connecting extensional fault and 15 s later ruptured the two main segments with dominantly strike-slip motion. We show that complexities in the fault geometry at depth explain well the complex pattern of radiated seismic waves. We conclude that the location and detailed characteristics of the earthquake could not have been anticipated on the basis of observations of surface geology alone

Selective impairment of hippocampal gamma oscillations in connexin-36 knock-out mouse in vivo.

The physiological roles of neuronal gap junctions in the intact brain are not known. The recent generation of the connexin-36 knock-out (Cx36 KO) mouse has offered a unique opportunity to examine this problem. Recent in vitro recordings in Cx36 KO mice suggested that Cx36 gap junction contributes to various oscillatory patterns in the theta (approximately 5-10 Hz) and gamma (approximately 30-80 Hz) frequency ranges and affects certain aspects of high-frequency (>100 Hz) patterns. However, the relevance of these pharmacologically induced patterns to the intact brain is not known. We recorded field potentials and unit activity in the CA1 stratum pyramidale of the hippocampus in the behaving wild-type (WT) and Cx36 KO mice. Fast-field "ripple" oscillations (140-200 Hz) were present in both WT and KO mice and did not differ significantly in power, intraepisode frequency, or probability of occurrence. Thus, fast-field oscillations either may not require electrical synapses or may be mediated by a hitherto unknown class of gap junctions. Theta oscillations, recorded during either wheel running or rapid eye movement sleep, were not different either. However, the power in the gamma frequency band and the magnitude of theta-phase modulation of gamma power were significantly decreased in KO mice compared with WT controls during wheel running. This suggests that Cx36 interneuronal gap junctions selectively contribute to gamma oscillations

Hidden in plain sight: What remains to be discovered in the eukaryotic proteome?

The first decade of genome sequencing stimulated an explosion in the characterization of unknown proteins. More recently, the pace of functional discovery has slowed, leaving around 20% of the proteins even in well-studied model organisms without informative descriptions of their biological roles. Remarkably, many uncharacterized proteins are conserved from yeasts to human, suggesting that they contribute to fundamental biological processes. To fully understand biological systems in health and disease, we need to account for every part of the system. Unstudied proteins thus represent a collective blind spot that limits the progress of both basic and applied biosciences. We use a simple yet powerful metric based on Gene Ontology (GO) biological process terms to define characterized and uncharacterized proteins for human, budding yeast, and fission yeast. We then identify a set of conserved but unstudied proteins in S. pombe , and classify them based on a combination of orthogonal attributes determined by large-scale experimental and comparative methods. Finally, we explore possible reasons why these proteins remain neglected and propose courses of action to raise their profile and thereby reap the benefits of completing the catalog of proteins' biological roles

Super-resolution far-field ghost imaging via compressive sampling

Much more image details can be resolved by improving the system's imaging resolution and enhancing the resolution beyond the system's Rayleigh diffraction limit is generally called super-resolution. By combining the sparse prior property of images with the ghost imaging method, we demonstrated experimentally that super-resolution imaging can be nonlocally achieved in the far field even without looking at the object. Physical explanation of super-resolution ghost imaging via compressive sampling and its potential applications are also discussed.Comment: 4pages,4figure