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Dissolved oxygen (DO) is an important parameter in assessing water quality. The reduction in DO concentration is the result of eutrophication, which degrades the quality of water. Aeration is the best way to enhance the DO concentration. In the current study, the aeration efficiency (E20) of various numbers of circular jets in an open channel was experimentally investigated for different channel angle of inclination (θ), discharge (Q), number of jets (Jn), Froude number (Fr), and hydraulic radius of each jet (HRJn). The statistical results show that jets from 8 to 64 significantly provide aeration in the open channel. The aeration efficiency and input parameters are modelled into a linear relationship. Additionally, utilizing WEKA software, three soft computing models for predicting aeration efficiency were created with Artificial Neural Network (ANN), M5P, and Random Forest (RF). Performance evaluation results and box plot have shown that ANN is the outperforming model with correlation coefficient (CC) = 0.9823, mean absolute error (MAE) = 0.0098, and root mean square error (RMSE) = 0.0123 during the testing stage. In order to assess the influence of different input factors on the E20 of jets, a sensitivity analysis was conducted using the most effective model, i.e., ANN. The sensitivity analysis results indicate that the angle of inclination is the most influential input variable in predicting E20, followed by discharge and the number of jets. [ABSTRACT FROM AUTHOR]

There are concerns about the risk of injuries caused by marathons in China. Since male and female runners have different injury risks, gender differences in running shoe functionality should be further complemented. A supervised questionnaire survey of 626 marathon runners was collected. The questionnaire was categorized into four sections: (1) participant profile, (2) importance of shoe properties, (3) functional evaluation of shoe properties and (4) importance ranking of shoe properties. The Mann–Whitney U test, Fisher's exact test of cross tabulation and Chi-square test, and two-way ANOVA were used to analyze the results of this survey. The significance level was set at P < 0.05. The full marathon participants were older than the half marathon participants. There was no gender difference in the importance of shoe features to elite runners. In addition, women are more concerned about upper elasticity and have higher requirements for running shoes than men. Women were more focused on injury prevention, while men were more focused on running performance. Heel cushioning was identified by all participants as the most important running shoe feature. There were no gender differences between elite players' demand for running shoes, but significant gender differences were found between genders at other running levels. [ABSTRACT FROM AUTHOR]

The aim of this present work was to study the applicability of waste marble dust (MD) in poly(lactic acid) (PLA)-based composites. Samples containing up to 20 wt% waste MD were prepared via melt blending. The attention was focused on the investigation of mechanical, morphological, thermal properties and the wear resistance of the PLA/MD composites. Regarding the mechanical properties, both the tensile and the flexural modulus improved remarkably, however, a slight loss was observed in strength and deformability. The impact toughness showed an increasing tendency up to 10 wt% MD loading, which was followed by a marginal decrease at higher concentration. With respect to the sliding wear rate, the composite with the highest MD content showed the best wear resistance. According to the DSC measurements, the MD hampered the chain mobility of PLA, thereby reducing the crystalline ratio. Overall, composites with improved properties were developed, while the reuse of waste MD is expected to reduce the production costs as well. [ABSTRACT FROM AUTHOR]

This study examined the effects of silicon nitride reinforcement on physical, mechanical and wear properties of different ceramic (zirconium oxide, magnesium oxide, chromium oxide and aluminum oxide) containing hip implant composites. The hip implant composites were produced using conventional mixing and spark plasma sintering methods by substituting aluminum oxide (68, 70.5, 73 and 75.5 wt.%) with silicon nitride (0, 2.5, 5 and 7.5 wt.%). Experimental results showed that silicon nitride content had significant effect on the evaluated physical, mechanical and wear properties. The density of the composites found to decrease whereas void content, Young's modulus, hardness, wear resistance and fracture toughness first decreased (for 2.5 wt.%) and then increased with the increasing amount of silicon nitride content. The maximum hardness, Young's modulus, wear resistance and fracture toughness values of 28.64 GPa, 280.18 GPa, 0.0076 mm3/million cycles and 11.84 MPa.m1/2, respectively were registered for 2.5 wt.% silicon nitride additions that also had the lowest void content (0.38%). [ABSTRACT FROM AUTHOR]

In this research work, high-velocity oxy-fuel thermal spraying is used to develop TiAlN coatings on AA1050 and AA5083 aluminium alloy substrates. Slurry wear behavior of coatings is evaluated using jet-type test rig. Surface studies were carried out to investigate the potential erosion mechanism. The influence of key parameters identified using the Taguchi analysis is also corroborated with a wear model. The potential mechanism identified by wear model is in excellent convergence with that observed experimentally. Mixed ploughing and cutting, formation of platelets, abrasion grooves and cracks are witnessed as primary mechanisms causing loss of coating. Results indicate that impact velocity is recognized as a highly contributing parameter with contribution ratio of 79.24 and 83.75% followed by impingement angle with contribution ratio of 15.81 and 11.58% for AA1050 and AA5083, respectively. The important sequences of the control parameters are recognized to be impact velocity > impingement angle > erodent feed rate > erodent size for AA1050 and impact velocity > impingement angle > erodent size > erodent feed rate for AA5083. The best possible combination of control parameters for AA1050 and AA5083 to achieve minimal wear rate with respect to impact velocity, erodent size, impingement angle and erodent feed rate is 30 m/s, 225 µm, 30°, 160 g/min and 25 m/s, 150 µm, 30°, 160 g/min, respectively. [ABSTRACT FROM AUTHOR]

Purpose: This study examined differences in ankle motion and plantar pressure between habitually barefoot male (HBM) and habitually shod male (HSM) during vertical jump. Methods: Eighteen habitually barefoot males and twenty habitually shod males volunteered to join the test. Distance between hallux and second toe was measured with Easy-Foot-Scan. Plantar pressure and ankle kinematics were measured with EMED force platform and Vicon motion analysis system respectively. T test was taken to analyse the significant differences using Stata 12.0 software. Results: The distance between hallux and other toes in HBM was greater than it in HSM. HBM showed larger plantar loading under hallux and medial forefoot, while HSM showed lager plantar loading under medial and central forefoot. HBM had smaller ankle plantarflexion, eversion and external rotation than HSM. Conclusion: Findings of this study provide basic information for further studies on different hallux/toe function in motion control between habitually shod and barefoot populations. [ABSTRACT FROM AUTHOR]