Open Access Original Research Article

Spectrum Diagnostics of a Damaged Differential Planetary Gear during Various Operating Conditions

Xi Wu, Andrew Sommer, Jim Meagher

Physical Science International Journal, Page 1-13
DOI: 10.9734/PSIJ/2016/22868

Planetary gears are identified as compact alternatives to fixed-axis gear trains and show more complicated dynamical behavior due to the nonlinearity induced by the interaction between backlash and tooth defects. The majority of current publications are based on theoretical models of ideal planetary gears, and therefore cannot simulate the time varying dynamic forces induced by damaged teeth. By utilizing a multi-body dynamics and motion analysis software, this paper presents unpublished vibration spectra and fault indicators of a ubiquitous multi-input industrial differential planetary design that includes tooth damage. Backlash between the sun and planet gears are precisely dimensioned to avoid teeth interference and undercut. The region of point-to-point contact along the involute profile is modeled elastically and accounts for tooth flexibility. Boundary conditions that closely match realistic operation are considered, including component constraints, resistive bearing torques, and direct modification of the software parametric resolution. Torsional vibration induced by backlash and tooth geometry errors is shown to cause teeth separation and double-sided impacts in unloaded and lightly loaded gearing drives. Frequency analyses reveal distinct sideband modulations of the gear mesh along with sub and super harmonics. The sideband components, which comprise a large portion of the vibration, are used as fatigue diagnostics by identifying the location of manufacturing errors. Additionally, a joint time-frequency analysis (JTFA) is applied to transient start-up conditions that illustrates an oscillating spectrum in which contact forces increase during acceleration. To the best of our knowledge no research results have been published in fault detection of planetary gears using JTFA.

 

Open Access Original Research Article

Riemannian Acceleration in Cartesian Coordinate Based Upon the Golden Metric Tensor

D. J. Koffa, J. F. Omonile, O. O. Ogunleye, J. A. Rabba, S. X. K. Howusu

Physical Science International Journal, Page 1-7
DOI: 10.9734/PSIJ/2016/23360

Geometric quantities in all orthogonal curvilinear co-ordinates are built upon Euclidean geometry. This geometry is founded on a well known metric tensor called the Euclidean metric tensor. Riemannian geometry which is assumed to be more general than the Euclidean geometry was founded on an unknown metric tensor for spacetimes in gravitational fields. Therefore the Riemannian geometry itself could not be opened up for exploration and exploitation, let alone the possible application to theoretical physics. But with the discovery of a general Riemannian metric tensor called the golden metric tensor, exploitation of Riemannian geometry is now possible. We are in a position to calculate all the theoretical predictions of Riemann’s geometrical and physical concepts and principles and compare them with experimental physical evidence. In this paper, we use the golden metric tensor to develop Riemannian acceleration in the Cartesian coordinate for application in theoretical physics and other related fields.

 

Open Access Original Research Article

Energy Spectra of the Graphene-based Fibonacci Superlattice Modulated by the Fermi Velocity Barriers

A. M. Korol, S. I. Litvynchuk, S. V. Bagliuk, V. M. Isai

Physical Science International Journal, Page 1-8
DOI: 10.9734/PSIJ/2016/23236

The one-dimensional superlattice (SL) based on a monolayer graphene modulated by the Fermi velocity barriers is considered. We assume that the rectangular barriers are arranged periodically along the SL chain. The energy spectra of the Weyl-Dirac quasi-electrons for this SL are calculated with the help of the transfer matrix method in the continuum model. The Fibonacci quasi-periodic modulation in graphene superlattices with the velocity barriers can be effectively realized by virtue of a difference in the velocity barrier values (no additional factor is needed). And this fact is true for a case of normal incidence of quasi-electrons on a lattice. In contrast to the case of other types of the graphene SL spectra studied reveal the periodic character over all the energy scale and the transmission coefficient doesn’t tend asymptotically to unity at rather large energies. The dependence of spectra on the Fermi velocity magnitude and on the external electrostatic potential as well as on the SL geometrical parameters (width of barriers and quantum wells) is analyzed. The obtained results can be used for applications in the graphene-based electronics.

 

Open Access Original Research Article

XRD and SEM of Bi4-xLaxTi3O12 Ceramics

Satishkumar S. Lature, Ghanshyam H. Jadhav

Physical Science International Journal, Page 1-7
DOI: 10.9734/PSIJ/2016/23113

La-doped bismuth titanate ceramics with composition formula Bi4-xLaxTi3O12 (0 ≤ x ≤ 1.5) was synthesized by solid-state reaction route. These ferroelectric materials find great applications in nonvolatile memories. The x-ray diffraction was carried out to analyze the structures of synthesized ceramics. The x-ray diffraction data revealed that there was a structural phase transformation from pseudo-orthorhombic to tetragonal, for x = 0.75, which was confirmed from (h 0 0), (h k 0) and (h 0 l) planes. SEM images were taken at a magnification of x1000. The Archimedes principle was used to calculate the density of sintered ceramic samples, which was in the range of 81-94% of theoretical value.

 

Open Access Original Research Article

Preparation and Testing the Hyperthermia Property of Electrospun Micro and Nanofibers

Araz Boghozian, Chris W. Draper, Jose D. Jimenez, Jesus Rodriguez, Menooa Zohrabian, Lihua Zhang, Yong X. Gan

Physical Science International Journal, Page 1-8
DOI: 10.9734/PSIJ/2016/23331

The hyperthermia properties of nanomaterials have received attention in recent years due to the advances in nanofiber production. One of the main proponents is the medical field where it is used to combat malignant cancer cells. In this work we confirmed that a polymer solution containing titanium cobalt compounds as precursors can be electrospun into fibers and transformed into a ceramic oxide after heat treatment. After heat treatment the fiber size is reduced. The size of the fiber is in the range from nanoscale to the microscale. The fiber shows intensive hyperthermia behavior in the electromagnetic field. The temperature increases from 22 to 40°C when it is heated for 30 s. The surface temperature of the heat treated specimen increases less during the hyperthermia test as compared with that of the unheated specimen.

 

Open Access Original Research Article

Neutronics Study of NIRR-1 Fuelled with 19.75% UO2 Material Using Venture-PC and Scale 6.1 Codes

D. O. Samson, M. Y. Onimisi, A. Salawu, J. A. Rabba

Physical Science International Journal, Page 1-9
DOI: 10.9734/PSIJ/2016/23545

A comprehensive neutronics analysis using VENTURE-PC and SCALE 6.1 computer codes system has been performed for the core conversion study of Nigeria Research Reactor-1 (NIRR-1). The computed reactor core physics parameters include: group neutron fluxes profiles, power density distributions and neutron flux distributions. The number of active fuel pins used for this analysis is approximate 200 pins, which show that the fuel pins have been reduced to about 58% when compared with the present Highly Enriched Uranium (HEU) fuel (UAl4-Al) of 347 pins. These reductions in the number of fuel pins has given room for more moderators in the core and hence increase the number of hydrogen available to thermalize the neutron in the potential 19.75% UO2 fuelled core for Nigeria Research Reactor-1 (NIRR-1). The diffusion theory based calculated values of thermal flux profiles for the vertical as well as for the horizontal radial directions has been found to agree well with similar calculations using different nuclear analysis tools. The results obtained will qualify uranium dioxide (UO2) fuel as the potential material for future Low Enriched Uranium (LEU) core conversion of Nigeria Miniature Neutron Source Reactors (MNSRs).