Split torque transmission load sharing

Split torque transmissions are attractive alternatives to conventional planetary designs for helicopter transmissions. The split torque designs can offer lighter weight and fewer parts but have not been used extensively for lack of experience, especially with obtaining proper load sharing. Two split torque designs that use different load sharing methods have been studied. Precise indexing and alignment of the geartrain to produce acceptable load sharing has been demonstrated. An elastomeric torque splitter that has large torsional compliance and damping produces even better load sharing while reducing dynamic transmission error and noise. However, the elastomeric torque splitter as now configured is not capable over the full range of operating conditions of a fielded system. A thrust balancing load sharing device was evaluated. Friction forces that oppose the motion of the balance mechanism are significant. A static analysis suggests increasing the helix angle of the input pinion of the thrust balancing design. Also, dynamic analysis of this design predicts good load sharing and significant torsional response to accumulative pitch errors of the gears

Tailorable optical scattering properties of the V-shaped plasmonic nano-antennas: a computationally efficient and fast analysis

We introduce an efficient computational scheme based on Macro Basis Function (MBF) method, to analyze the scattering of a plane wave by the V-shaped plasmonic optical nano-antennas. The polarization currents and the scattered fields for symmetric and anti-symmetric excitations are investigated. We investigate how the resonant frequency of the plasmonic V-shaped nanoantenna is tailored by engineering the geometrical parameters and by changing the polarization state of the incident plane wave. The computational model presented herein is faster by orders of magnitude than commercially available finite methods and is capable to characterize also other nanoantennas comprising of junctions and bends of nanorods.Comment: Final version published in JOSA A (6 pages, 9 figures). Work sponsored by DARPA/MTO Young Faculty Award #N66001-11-1-414

Particle Creation from Vacuum by Lorentz Violation

It is shown that the vacuum state in presence of Lorentz violation can be followed by a particle-full universe that represents the current status of the universe. In this model the modification in dispersion relation (Lorentz violation) is picked up representing the regime of quantum gravity. The result can be interpreted such that the existence of the particles is an evidence for quantum effects of gravity in the past. It is concluded that only the vacuum state is sufficient to appear the matter fields spontaneously after the process of semi-classical analysis.Comment: 9 pages, 2 figure

Removing the Big Bang Singularity: The role of the generalized uncertainty principle in quantum gravity

The possibility of avoiding the big bang singularity by means of a generalized uncertainty principle is investigated. In relation with this matter, the statistical mechanics of a free-particle system obeying the generalized uncertainty principle is studied and it is shown that the entropy of the system has a finite value in the infinite temperature limit. It is then argued that negative temperatures and negative pressures are possible in this system. Finally, it is shown that this model can remove the big bang singularity.Comment: 8 pages, Accepted for publication in Astrophysics & Space Scienc

On the Reynolds-Averaged Navier-Stokes Modelling of the Flow around a Simplified Train in Crosswinds

Currently, there are different computational fluid dynamic (CFD) techniques used to obtain the flow around trains. One of these techniques is the Reynolds-averaged Navier-Stokes (RANS), which is commonly and widely used by industry to obtain the mean flow field around trains in different operating conditions. In order to assess the performance of RANS turbulence modelling for train aerodynamics, five different common RANS modelling have been used in this paper to obtain the flow and the surface pressure around a simplified train model subjected to crosswind; the standard k- model, the realisable k- model, the Re-Normalisation Group (RNG) k- model, the standard k- model and Shear Stress Transport (SST) k- model. The train model was stationary and subjected to crosswind with a 90o yaw angle. The effects of mesh size and spatial discretization scheme on the aerodynamic characteristics of the train were also investigated. The results obtained from the different RANS models were compared to those from published experimental data. In general, all the RANS models provided the pressure distribution trend. However, all k- models overestimate the surface pressure on the train body except the bottom face. The standard k- model underestimates the surface pressure on the train body except the streamwise face. It was shown that the simulation using SST k- model together with a second order discretization scheme provides the closest results to the experimental surface pressure. It could be concluded from the present study that the SST k-model with a second order discretization scheme and y+ around 1.0 is the most appropriate RANS model for simulating the flow around trains subjected to crosswinds

Religious faith and psychosocial adaptation among stroke patients in Kuwait: A mixed method study

This is the author's accepted manuscript. The final published article is available from the link below. Copyright @ 2012 Springer Science+Business Media.Religious faith is central to life for Muslim patients in Kuwait, so it may influence adaptation and rehabilitation. This study explored quantitative associations among religious faith, self-efficacy, and life satisfaction in 40 female stroke patients and explored the influence of religion within stroke rehabilitation through qualitative interviews with 12 health professionals. The quantitative measure of religious faith did not relate to life satisfaction or self-efficacy in stroke patients. However, the health professionals described religious coping as influencing adaptation post-stroke. Fatalistic beliefs were thought to have mixed influences on rehabilitation. Measuring religious faith among Muslims through a standardized scale is debated. The qualitative accounts suggest that religious beliefs need to be acknowledged in stroke rehabilitation in Kuwait

Cobalt-Based Metallic Glass Microfibers for Flexible Electromagnetic Shielding and Soft Magnetic Properties

Thin and flexible materials that can provide efficient electromagnetic interference (EMI) shielding are urgently needed, particularly those that can be rapidly processed and withstand harsh environments. Cobalt-based metallic glasses stand out as prime candidates due to their excellent soft magnetic properties, satisfactory shielding features, and mechanical properties. Herein, a recently developed technique is used to fabricate metallic glass microfibers from Co66Fe4Mo2Si16B12 alloy. The produced microfibers are characterized for their size and uniformity by scanning electron microscopy and their amorphous structure is confirmed by X-ray diffraction (XRD) and differential scanning calorimetry (DSC). The cobalt-based metallic glass microfibers show an EMI shielding factor that reaches five in the static regime and obtains an up to 25-fold increase of the attenuation constant in the Ku frequency band. This performance originates from the combination of soft magnetic properties and excellent electrical conductivity. In addition, the flexible microfibers exhibit excellent hardness and elasticity making them suitable for EMI shielding of complex geometries. Their hardness and elastic modulus are measured by nanoindentation to be 11.31 +/- 0.60 GPa, and 110.54 +/- 11.24 GPa, respectively.A novel method is used to fabricate flexible Co66Fe4Mo2Si16B12 metallic-glass microfibers for electronics, boasting a hardness of 11.31 +/- 0.60 GPa and an elastic modulus of 110.54 +/- 11.24 GPa. Their EMI shielding exhibits clear anisotropy with a factor of 5 and up to 25-fold increased attenuation in the Ku band. These properties position them well for EMI shielding in intricate geometries.imag