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91.
The constrained blister test is investigated through finite element analysis to determine the applicabilities and the limitations of the new technique. Numerical results confirm that the strain energy release rate asymptotically approaches a constant value. These results also show that the test technique and the approximate solution for strain energy release rate are applicable for some practical cases. 相似文献
92.
Effect of additives on formation of natural gas hydrate 总被引:1,自引:0,他引:1
The formation of natural gas hydrate (NGH) is studied in this work. Kinetics data of hydrate formation with no agitation were collected at various concentrations of the aqueous solutions with different additives such as alkylpolyglucside, sodium dodecyl benzene sulfonate and potassium oxalate monohydrate. Various kinds of additive increased the formation rates of NGH and its storage capacity and reduced the induction time of NGH formation. Moreover, the storage capacity, the induction time and the hydrate formation rate were influenced by the concentration of the aqueous solution. 相似文献
93.
94.
Ahmet Kolus Philippe-Antoine Dubé Daniel Imbeau Richard Labib Denise Dubeau 《Applied ergonomics》2014
In new approaches based on adaptive neuro-fuzzy systems (ANFIS) and analytical method, heart rate (HR) measurements were used to estimate oxygen consumption (VO2). Thirty-five participants performed Meyer and Flenghi's step-test (eight of which performed regeneration release work), during which heart rate and oxygen consumption were measured. Two individualized models and a General ANFIS model that does not require individual calibration were developed. Results indicated the superior precision achieved with individualized ANFIS modelling (RMSE = 1.0 and 2.8 ml/kg min in laboratory and field, respectively). The analytical model outperformed the traditional linear calibration and Flex-HR methods with field data. The General ANFIS model's estimates of VO2 were not significantly different from actual field VO2 measurements (RMSE = 3.5 ml/kg min). With its ease of use and low implementation cost, the General ANFIS model shows potential to replace any of the traditional individualized methods for VO2 estimation from HR data collected in the field. 相似文献
95.
Evandro Eduardo Broday Antonio Augusto de Paula XavierReginaldo de Oliveira 《International Journal of Industrial Ergonomics》2014
The incorrect determination of metabolic rate can be linked to discrepancies between the model of the PMV (Predicted Mean Vote) and real thermal sensation collected in field studies. Aiming to improve the correlation of the PMV model and the real thermal sensation, this work established new values for the metabolic rate: one way being called “calculated” using Newton's Method and the other called "measured" using a metabolic analyzer. Welder's activities were evaluated, through the measurements of environmental and personal variables. New values of metabolic rate were determined for this activity. The values found for the calculated form and the measured one were, respectively, 178.63 and 145.46 W/m2, different from the range provided by the table of ISO 8996 (2004) for this activity (75–125 W/m2). In order to verify which of the values of the metabolic rate was closer to the real thermal sensation of PMV, a linear regression was made between the PMV and the real thermal sensation in three ways: S × PMVtabulated (R2 = 0.1749), S × PMVcalculated (R ² = 0.7481) and S × PMVmeasured (R2 = 0.7854). It was found that the values measured by the instrument gave a higher coefficient of determination which was chosen for the correction of the table. The correction of the table provides a value of Mpredicted, that is a value of metabolic rate that corrects the values provided by the tables of ISO 8996 (2004), by means of a correction coefficient. For the welder's activities in a metal-mechanics industry, tabulated values can be multiplied by the correction coefficient 1.4648 in order to minimize inaccuracies. The PMVpredicted, obtained through the Mpredicted, when related to the actual thermal sensation, provides a coefficient of determination of 0.7511, thereby improving the model of the PMV. 相似文献
96.
L. Rodríguez-Liñares M.J. Lado X.A. Vila A.J. Méndez P. Cuesta 《Computer methods and programs in biomedicine》2014
In this paper, the gHRV software tool is presented. It is a simple, free and portable tool developed in python for analysing heart rate variability. It includes a graphical user interface and it can import files in multiple formats, analyse time intervals in the signal, test statistical significance and export the results. 相似文献
97.
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99.
设计了一款PWM控制模式降压式(buck)直流一直流转换器芯片。该芯片为电压反馈控制模式,内部补偿使得反馈控制有很好的线性和很快的负载响应而无需通过外部设计。芯片采用CMSC0.5μm BCD工艺实现。PSPICE仿真结果表明,输出电压只有大约50mY的纹波,静态电流为3mA左右。输出电压在低于0.5V时,芯片具有短路降频功能,工作频率由81KHz降到23KHz左右,输出负载由0.2A跳变到2A时具有很好的负载调整率,大约为0.2%,转换效率可以达到85%以上。 相似文献
100.
针对多目标分布估计算法全局收敛性较弱的缺陷,提出了一种自适应混合多目标分布估计进化算法。其基本思想是:在多目标分布估计算法中引入全局收敛性较强的差分进化算法,当函数变化率较大时,用分布估计算法产生新种群;当函数变化率较小即算法可能陷入局部收敛时,用差分进化算法产生新种群。理论分析和数值实验结果表明,这种混合算法不仅具有良好的全局收敛性,而且解的分布性和均匀性较没有考虑目标函数变化率的混合多目标分布估计算法也有了一定程度的提高。 相似文献