Journal of Advanced Engineering and Computation
Call for paper - June - 2018 (Apr 12, 2017) More...
Friction and clearance always present in any mechanical system. Hence, the effects of friction and clearance on a dynamic system are so critical. This paper aims to investigate their effects on the dynamic response of a slider-crank mechanism with two sliders and imperfect joints. Firstly, the mechanism is created in Solidworks and then it is simulated via finite element method in ANSYS. The dynamic simulation are conducted to evaluate the mentioned effects. The results revealed that the effect degree of clearance on the dynamic behaviors of the proposed mechanisms is significantly higher than that of friction. Also, the results indicated that the velocities, acceleration, and contact force graph are almost same at different friction coefficient. However, compared with ideal joint case, they had a maximum value and an unstable oscillation. This problem is due to journal collide into bearing induced the maximum values of contact force. The results of this study are a helpful guidance to practitioners, scientists, and engineers.
In recent years, harvesting energy from radio frequency (RF) signals has drawn significant research interest as a promising solution to solve the energy problem. In this paper, we analyze the effect of the interference noise on the wireless energy harvesting performance of a decode-and-forward (DF) relaying network. In this analysis, the energy and information are transferred from the source to the relay nodes in the delay-limited transmission and Delay-tolerant transmission modes by two methods: i) time switching protocol and ii) power splitting protocol. Firstly, due to the constraint of the wireless energy harvesting at the relay node, the analytical mathematical expressions of the achievable throughput, outage probability and ergodic capacity of both schemes were proposed and demonstrated. After that, the effect of various system parameters on the system performance is rigorously studied with closed-form expressions for system throughput, outage probability, and ergodic capacity. Finally, the analytical results are also demonstrated by Monte-Carlo simulation. The results show that the analytical mathematical and simulated results agree with each other.
Risk assessment is a vital element of most maintenance system, this is because safeguarding of equipment item requires maintenance strategies which usually depend on the degree of risk of the equipment item. In this paper two risk assessment tools; Risk Priority Number (RPN) based approach and Risk Matrix (RM) based approach, are presented for categorisation of risk of failure modes of marine diesel engine. The techniques are used to categorise failure modes into three risk levels; low, medium and high in turn and based on the risk level, maintenance strategy are assigned to each failure modes. Furthermore, the two techniques are compared and the result of the analysis revealed that, the extent of Risk matrix method similarity to the RPN approach depends on the benchmark for setting the risk level limit in the RPN method.
In , the authors propose an accurate method, namely the correction method, for computing hydrodynamic interaction between very closed spherical particles in a Stokes fluid. The accuracy of this method depends on two truncation parameters for approximating the Neumann to Dirichlet matrix and the velocity correction respectively. In this paper, we establish a numerical determination to estimate these parameters. We perform some numerical experiments to present our method.
In this paper, by mixing the red-emitting α-SrO·3B2O3:Sm2+ conversion phosphor to yellow-emitting YAG:Ce phosphor compound, an innovative recommendation for increasing optical performance of white LEDs (WLEDs) with remote packaging, which has an average correlated color temperature (CCT) of 700K and 8500K, is proposed and demonstrated. By varying α-SrO·3B2O3:Sm2+ concentration from 2% to 24 %, the obtained results indicated that color uniformity, color rendering index (CRI), color quality scale (CQS), and luminous flux could be improved significantly. The results demonstrated a prospective recommendation for manufacturing remote packaging phosphor WLEDs.
Enhancement of the color uniformity, the lumen output of the multi-chip white LED lamps (MCW-LEDs) at high color correlated temperature is a big challenge for researchers. However, an innovative LED lamp designed with a phosphor compounding, which combines (La,Ce,Tb) PO4:Ce:Tb (LaTb) green phosphor with YAG: CE yellow phosphor, is proposed as an optimal solution to this requirement. Index, using LaTb green phosphor into MCWLEDs could bring a superior optical performance for MCW-LEDs. It is found that the lumen output of this new MCW-LED at a high color temperature of 8500 K significantly improves up to 1600 lm compared to MCW-LEDs without LaTb phosphor. The simulation results demonstrated that the CCT deviation sharply decreases from 9000 to 1000 at the LaTb concentration range from 0 to 1.8 %, while the Color Rendering Index ability (CRI) and the Color Quality Scale (CQS) slightly decrease. To obtain the highest lumen output and the best color uniformity, the particle size range within 6 - 8 µm should be suggested.