A method for the preliminary design of gears using a reduced number of American Gear Manufacturers Association (AGMA) correction factors

Typically, the preliminary design of mechanical components such as gears is carried out using standardized design processes such as those developed by the American Gear Manufacturers Association (AGMA). These design standards include a large number of ‘correction factors’ to account for various uncertainties. As the knowledge about these uncertainties increases, it becomes possible to include them systematically in the design procedure, thereby reducing the number of empirical correction factors. Robust design provides a way to design in the presence of various uncertainties. In this article, a design method is proposed to eliminate empirical correction factors and is demonstrated by eliminating two correction factors from the AGMA design standards for a spur gear, namely, the factor of safety in contact and the reliability factor by the formal introduction of uncertainty in the magnitude of load and material properties. The proposed method is illustrated with the design of an automotive gear with desired reliability, cost and robustness.     

Moisture Absorption Behavior of Treated and Untreated Eggshell Particulate Epoxy Composites

Weight gain and thickness swelling in bio-waste composites material leads to an adverse effect on properties. In the present investigation the effect of different environments (saline, mineral, kerosene, subzero temperature) on the physical properties of the composites which are fabricated with unboiled(untreated) and boiled(treated 200 °C) eggshell filler materials are studied. XRD, SEM and ultimate analysis of the unboiled and boiled eggshells are also studied. The composites of different weight percentage 4, 8 and 12 wt% of unboiled and boiled eggshell filler epoxy composites are fabricated by a hand lay-up technique. The 12 wt% of boiled eggshell particulates reinforced epoxy composites showed the highest weight gains when exposed to different environments. Least absorption rate observed was for 4 wt% eggshell filler composite in subzero temperature condition. The composites showed a peculiar environmental behavior when exposed to kerosene.

     

Mill tailings based composites as paste backfill in mines of U-bearing dolomitic limestone ore

This paper elaborates on the development of paste backfill using mill tailings generated during the processing of a uranium ore deposit hosted in dolomitic limestone. The tailings have been characterized in terms of the physical, chemical and mineralogical properties. Time-dependent rheological behaviors and geotechnical properties of cemented paste backfill (CPB) are also determined. The studies show that the mill tailing has the potential to form paste and the CPB has adequate strength to provide support to mine pillars, roofs, and walls.     

Electrical and optical properties of Indium sesquitelluride (In2Te3) thin films

Indium sesquitelluride (In₂Te₃) thin films were grown on glass substrates using a flash evaporation technique. The nature of contact phenomena of Ag, Sn, In, Zn, Al-(p) In₂Te₃ junctions had been investigated. Ag, Sn, In and Zn metals were found to provide ohmic contact for In₂Te₃ thin films. The variation of DC-electrical resistivity of In₂Te₃ thin films with temperature was studied at different substrate temperatures. The optical measurements revealed that the flash evaporated In₂Te₃ thin films possessing direct energy band-gap. The variation of optical energy gap with substrate temperature was investigated. Film thickness, substrate temperature, composition and crystallinity were found to determine the optimization of electrical and optical properties of In₂Te₃ thin film.     

Synthesis and characterization of gold-conjugated <Emphasis Type="Italic">Backhousia citriodora</Emphasis> nanoparticles and their anticancer activity against MCF-7 breast and HepG2 liver cancer cell lines

Environmentally benign-synthesized gold nanoparticles (Au-NPs) have received substantial attention owing to their biomedical applications, particularly in cancer therapy. In the current study, Backhousia citriodora (B. citriodora) leaf extract was applied as a reducing agent for one-pot synthesis of controlled size Au-NPs. The effect of various parameters such as reaction time, pH, and B. citriodora leaf boiling time on the synthesis of Au-NPs was studied. The characterization of the Au-NPs synthesized at 15.0-min incubation time showed colour change because of the surface plasma resonance band around 530.0 nm. TEM photographs showed spherical morphologies with an average size of 8.40 ± 0.084 nm and zeta potential value was ? 29.74 mV, indicating stability of the nanoparticles. The biomedical properties of Au-NPs and B. citriodora leaf extract showed strong DPPH radical scavenging. The in vitro anticancer activity determined using MTT assay exhibited that Au-NPs showed a significant dose-dependent reduction in the viability of the MCF-7 breast cancer cell line and the HepG2 liver cancer cell line with IC₅₀ values of 116.65 and 108.21 µg, respectively.     

Propagation of Waves Through Cylindrical Bore in a Cubic Micropolar Generalized Thermoelastic Medium

The article deals with the propagation of axial symmetric cylindrical surface waves in a cylindrical bore through a micropolar thermoelastic medium of infinite extent possessing cubic symmetry. The theories of generalized thermoelasticity developed by Lord and Shulman and Green and Lindsay are used to study the problem. The frequency equations, connecting the phase velocity with the wave number, radius of bore, and other material parameters for empty and liquid-filled bores are derived. Some special cases have been deduced. The numerical results obtained have been illustrated graphically to understand the behavior of the phase velocity and attenuation coefficient versus the wave number.