Steady state and stability characteristics of a hydrodynamic journal bearing with a non-Newtonian lubricant

The effect of the non-Newtonian behaviour of lubricants, resulting from the addition of polymers, on the performance of hydrodynamic journal bearings was investigated. An empirical fluid flow equation which adequately represents the flow behaviour of lubricant was used to obtain a modified form of Reynolds' equation. Finite difference numerical solutions were obtained for steady state conditions at various width-to-diameter ratios. The results show a strong influence of the width-to-diameter ratio on the load capacity of journal bearings. Linearised stiffness and damping coefficients were evaluated from the fluid film force equations for the unsteady motion of the journal centre and were used to predict the stability limits of a simple rigid rotor-bearing system which showed a reduction in threshold speeds. The steady state load capacity and stability limits were verified experimentally for finite width bearings.     

The effect of a non-Newtonian lubricant on piston ring lubrication

The effect of a non-Newtonian oil (shear thinning) on the lubrication of a piston ring is theoretically investigated. A variation of shear strain rate with shear stress that is cubic in form is used to obtain a modified form of the Reynolds equation (dynamic) applicable to a run-in ring profile which is considered to be a double parabola with a central straight portion. Numerical solutions are obtained for the film thickness, pressure and frictional force over a complete stroke for the case of a constant load. Results presented in non-dimensional form show that the effect of pseudo plasticity is to reduce slightly the minimum film thickness, peak pressure ratio and friction coefficient.     

Anatomical region segmentation method from dermoscopic images of pigmented skin lesions

Melanoma tumor can cause a serious life threatening problem in humans, if left untreated for a long time without early diagnosis. For early diagnosis of melanoma, it is more significant to develop novel methods based on biophysics analyses, molecular targets recognitions, and new image analysis criteria. In this article, anatomical region segmentation and diameter identification is proposed to detect melanoma from dermoscopic images. Four main steps of the proposed system are as follows: In the first step, the preprocessing is performed to smooth the melanoma extraction process. The region segmentation is done in the second step using watershed segmentation and Sobel operator. In the third step, the postprocessing procedures like as morphological open, canny edge detection also applied to improve the region of interest. Finally, the melanoma region is identified using color symmetry features. The proposed method is tested with two data sets to prove the performance proposed method. The proposed method achieved an accuracy of 95.31% and specificity of 98.3%, which is better than other methods. Experimental results show that the effectiveness of the proposed method and illustrate viability of real-time clinical applications.     

Synthesis of r-GO-incorporated CoWO4 nanostructure for high-performance supercapattery applications

The avant-garde supercapatteries have received substantial curiosity for their noteworthy electrochemical performance. Devising battery-type substances with appreciable electrocapacitive accomplishment and high electrical transmittance is imperative to boost the energy stowing knack of supercapattery devices. A pure CoWO₄ nanostructure and a composite of CoWO₄ incorporating r-GO were prepared by hydrothermal method. The XRD and FTIR results validated the effective development of high-quality CoWO₄ and r-GO. FESEM images reveal a nanosphere-like architecture of CoWO₄ over r-GO sheets. The pure and composite nanomaterials show good battery-like traits in electrochemical studies. The CoWO₄/r-GO electrode exhibits better electrochemical activity compared to pure sample. The specific capacitance (and specific charge capacity) calculated at a current density of 2 A g^?1 for CWO/r-GO and CWO is 382.7 A g^?1 (158.1 C g^?1) and 262.7 A g^?1 (105.1 C g^?1), respectively. The results obtained herein evince that the developed nanocomposite is a propitious electrode candidate for supercapattery.

     

Improved video streaming using MSVC and nonoverlapping zone routing multipath propagation over MANETs

Providing real‐time video streaming in mobile ad hoc networks is difficult because of the time‐dependent channel status and stringent service requirements. The currently existing route request‐reply–based multihop overlay networks cause considerable control overheads in video transmission resulting in loss of data and communication breakdown. Such networks are more suitable to nonstreaming video applications rather than to time‐sensitive video streaming applications. Therefore, a powerful mechanism needs to be adopted to handle the channel failures amicably and reduce latency effectively in time critical video streaming applications over mobile ad hoc networks. In order to be resilient to the channel failures and reduce latency in such applications, 2 strategies, namely, multistate video coding and 2‐tier–based nonoverlapping zone routing multipath propagation through directional antennas have respectively been incorporated. The performance of the proposed nonoverlapping zone routing multipath propagation system is compared with those of the existing multicast zone routing and zone‐based hierarchical link state routing protocols with parameters average end‐to‐end delay, routing overhead and packet delivery ratio using NS 2.34. The simulation results show that latency and resilience get considerably improved. Finally, the video quality of the proposed work has been verified by subjective and objective video testing methods.     

The lift on a disc immersed in a rotating granular bed

The discrete element method has been used to study the lift F_L on a stationary disc immersed coaxially in a slowly rotating cylinder containing a granular material. In a tall granular column, F_L rises with the immersion depth h, but reaches a roughly constant asymptote at large h, in agreement with previous studies. Our results indicate that the argument in some earlier studies that F_L is proportional to the static stress gradient is incorrect. Instead, our results show that the lift is caused by an asymmetry in the dilation and shear rate between the regions above and below the disc. We argue that the cause of the lift is similar to that in fluids, namely that it arises as a result of the disturbance in the velocity and density fields around the body due to its motion relative to the granular bed. © 2017 American Institute of Chemical Engineers AIChE J, 63: 5482–5489, 2017     

Detailed analysis on injection timing retardation and simultaneous technology in a biodiesel-powered compression ignition engine

ABSTRACT

This detailed study focuses mainly on the reduction of oxides of nitrogen emissions from CI engines. It also discusses about other emissions and performance parameters. Injection timing retardation and simultaneous technology methods have been employed for controlling oxides of nitrogen emissions by many researchers. This review paper studies on injection timing retardation and simultaneous technology and its effects on various operating parameters carried out in a biodiesel-powered CI engines. The objective of this work is to find the significance of injection parameters such as retardation of injection timing and simultaneous technology on the various emission parameters. This paper also deals upon the various methods of retardation of injection timing and simultaneous technology to examine the emissions such as HC, CO, NO_x, smoke, and particulate matters. The present study showed that widespread review on CI engine emission characteristics in a CI engine fuelled with biodiesel blends.     

FHT algorithm for length N=q.2m

Of late, the discrete Hartley transform (DHT) has become an important real-valued transform. Many fast algorithms for computing the DHT of sequence length N=2^m have been reported. Fast computation of the DHT of length N=q.2^m, where q is an odd integer, is proposed. The key feature of the algorithm is its flexibility in the choice of sequence length N, where N need not necessarily be a power of 2, while giving rise to a substantial reduction in computational complexity when compared to other algorithms     

γ-ray-induced degradation in ethylene–propylene copolymer

The stabilization of polypropylene-disposable medical syringes against the γ-ray-induced degradation has been the subject of active research during the last decade due to the large-scale use of γ-irradiation for sterilization purposes. Ethylene–propylene (EP) copolymers have been suggested as suitable alternatives to polypropylene for these purposes. In this article, we investigated the effect of irradiation dose and postirradiation time on the melt index and mechanical properties of an EP copolymer. We also determined the chemical changes occurring during irradiation and storage using IR spectroscopy and have made an attempt to co-relate the changes in chemical structure to the changes in mechanical properties and melt index measurements. © 1996 John Wiley & Sons, Inc.     

Performance of MWCNT-Reinforced SAC0307/Cu Solder Joint Under Multiple Reflow Cycles

The evolution of interfacial microstructure and its effect on shear strength under multiple reflow cycles for multi-walled carbon nanotubes (MWCNT)-reinforced Sn0.3Ag0.7Cu solder/copper joint was investigated. The melting characteristics, wettability and mechanical properties of the solder alloy were assessed. The addition of MWCNT in the range of 0.01–0.05 wt% improved the wettability, melting behaviour and mechanical strength of the SAC0307 solder alloy. The nanoparticles in small weight fraction (0.01–0.05 wt%) addition were more effective in retarding intermetallic compounds growth at the interface. Amongst all compositions studied, the SAC0307–0.05MWCNT nanocomposite showed significant improvement in the performance of SAC0307/Cu solder joint under multiple reflow condition. The nanoparticles’ reinforcement above 0.1 wt% of the solder alloy was ineffective in improving the solder performance due to increased clustering in the matrix.