Dynamic modeling of defective gears

The use of geared transmissions has a long history and a rich experience, which has allowed the development of an intense research activity that has led to modern design methods, mostly standardized and execution technologies that have become traditional. As the fundamental sciences have provided more and more in-depth and refined knowledge, namely performance algorithms of optimal synthesis, the design in the field of gear transmissions has evolved by integrating in the calculation methods a growing number of elements. of influence (materials, geometry, dimensional and shape deviations, heat treatments, kinematic, energetic, dynamic factors, etc.). Automated modeling and simulation currently allow the prediction of behavior - from all points of view of a transmission - during operation.

Synthesis, characterization, and antioxidant activity in vitro of selenium-Euryale ferox Salisb. polysaccharide

In order to obtain and explore selenide composed of selenium and polysaccharide, three parameters were selected to optimize the synthesis process of selenium-Euryale ferox Salisb. polysaccharide (Se-ESPS) by Box-Behnken design. Furthermore, ESPS-B1 separated from ESPS was selenitized to Se-ESPS-B1 by the optimal synthesis process, then the characterization, and antioxidant activity in vitro of Se-ESPS-B1 were explored. The result manifested that the Se content of Se-ESPS was (2.915 ± 0.03) mg/g according to the optimal synthesis process of Se-ESPS (reaction time at 5 h, reaction temperature at 81 ℃, weight ratio of Na2SeO3 to ESPS at 0.9 g/g). A series of detection results indicated that the characterizations of Se-ESPS-B1 were apparently distinguished from that of ESPS-B1. Moreover, the antioxidant experiments in vitro demonstrated that Se-ESPS-B1 could exert antioxidant activity by scavenging DPPH, ABTS,·OH, and increasing reduction ability. In conclusion, the synthesis process is an effective approach to harvest selenium-polysaccharide, and Se-ESPS-B1 may be utilized as a potential antioxidant or selenium nutritional supplement.

Multi-objective reliability-based optimal synthesis of path generating four-bar mechanisms: A cooperative game theoretic approach

In this study, a novel approach based on synergy of cooperative game theory, reliability-based design optimization (RBDO) and Monte Carlo simulation (MCS) is proposed to address the reliability-based multi-objective optimal synthesis of path generating four-bar mechanisms, taking into account the influence of dimensional uncertainty on the reliability of mechanism. Tracking error ([Formula: see text]), deviation of transmission angle from 90° ([Formula: see text]) and probability of failure of Grashof constraint are defined as three performance criteria whose minimization enhance the precision, quality of motion and reliability of mechanism, respectively. To do so, three objective functions are considered, namely, precision ([Formula: see text]), quality of motion ([Formula: see text]) and reliability ([Formula: see text]); each objective function is assigned to a player. To conduct the optimization procedure, a game model is proposed, in which the cooperative game scenario is employed by defining a Nash bargaining function to model the interaction between players. In this way, the three-objective optimum design of mechanism is cast into a single-objective optimization problem. The comparisons of the obtained results using the method of this research with those reported in the literature shows a significant improvement in reliability of mechanism, whilst both precision and quality of motion in deterministic design is maintained. Particularly, the tracking error and the deviation of transmission angle from 90° of the synthesized mechanism is 0.0006 and 666.36 respectively, whilst the reliability is guaranteed since no violation of Grashof constraint occurs in the presence of 10% parameter uncertainty.