Efficient point-by-point engine calibration using machine learning and sequential design of experiment strategies     

Pak Kin Wong  Xiang Hui Gao  Ka In Wong  Chi Man Vong 《Journal of The Franklin Institute》2018,355(4):1517-1538

Modern engines are controlled by electronic control units, which operate all the engine actuators based on the signals from various sensors in the engine. Traditionally, the control parameters of the actuators are obtained through huge amount of trial-and-error experiments. However, using traditional approach to calibrate these parameters becomes more challenging with the increasing incorporation of new technologies into advanced engines. In order to reduce the number of experiments required in the calibration process of modern engines, a novel point-by-point engine calibration approach based on machine learning methods is proposed in this study. It is an iterative procedure that, for a given operating point, sequential design of experiment (DoE) strategy is utilized to measure the responses of different engine sensors corresponding to different actuator signals, and a machine learning algorithm called initial-training-free online extreme learning machine is utilized to incrementally learn the relationship between the sensors and actuators based on the measurement acquired. In each iterative cycle, meta-heuristic optimization is performed on the machine-learning-based model to search for the best parameters, which are then used as the initial parameters for generating DoE plan of the next cycle. The iteration is repeated until the optimal parameters of that operating point are found. To verify the effectiveness of the proposed approach, experiments on both simulation engine in commercial software and real engine in test bench have been conducted. The results show that the engine calibration can be carried out with significant fewer experiments and time by using the proposed approach.  相似文献   

Long-term Tai Chi exercise increases body stability of the elderly during stair ascent under high and low illumination*     

Qipeng Song  Shen Wang  Del P. Wong  Jingyi Zhou  Wei Sun  Cui Zhang 《Sports biomechanics / International Society of Biomechanics in Sports》2018,17(3):402-413

The effects of long-term Tai Chi exercise on body stability of the elderly during stair ascent under high and low illumination were investigated. Forty-five healthy elderly women were divided into three groups, namely, Tai Chi exercise group, brisk walking group and no-exercise control group. All the participants ascended a staircase, during which force platforms and a motion capture system collected the data. Under the high illumination, Tai Chi exercise participants exhibited higher loading rate and anteroposterior centre of pressure (COP_ap) displacement as well as a lower braking impulse than no-exercise group. Under the low illumination, Tai Chi exercise participants demonstrated higher COP_ap and mediolateral centre of pressure (COP_ml) displacements as well as lower braking and lateral impulses compared with no-exercise participants. The centre of mass (COM)_ml sway in Tai Chi and no exercise participants were higher, the loading rates in Tai Chi and walking participants were higher, and the lateral impulse in no exercise participants was higher under low illumination than under high illumination. Thus, low illumination increases the risk of falling. Tai Chi participants increased their foot clearance, head inclination angle and COP_ap displacement under low illumination to increase their stability during stair ascent.  相似文献   

初始缺陷和拉-弯耦合对于叠层板的振动屈曲和非线性动力稳定性的影响     

王列东  刘正宁  周承倜 《大连大学学报》1998,(4)

研究了复合材料叠层板的初始缺陷和拉伸-弯曲耦合对于其振动、屈曲和非线性动力稳定性的影响,推导了控制方程,这是一个修正的非线性Mathieu方程,进行了5种典型复合材料的数值计算,它们是玻璃环氧Scotch-1002,芳纶环氧Kevlar-49,硼环氧B4/5505,石墨环氧T300/5208和AS/3501,结果表明,由于初始缺陷以及耦合效应的存在,使叠层板对于进入参数共振更加敏感,并且其振幅大于无初始缺陷或者无耦合效应的叠层板,对于不同材料的复合叠层板,尤其是层数较少的板,耦合效应是不相同的,在板结构的屈曲和动力稳定性设计中,如果忽略了耦合效应的影响,其不安全性将超过10％以上。  相似文献   

The effects of expressions of fear induced by background music on reading comprehension     

Agnes S.K. Wong  Matthew Moreno  Samantha Burns  Earl Woodruff 《Journal of Research in Reading》2023,46(2):143-162

Background

Research has suggested that background music can have a positive or negative effect that can influence the affective state of individuals. Although research has demonstrated that fear negatively influences our cognitive performance, there is a research gap in understanding the combined effects of different background music tempo and fear in influencing reading comprehension performance.

Methods

Data were collected from 70 participants enrolled at a public university in Canada. Participants were required to listen to background music of varying speeds with three conditions (no music, slow music and fast music). We adopted a cross-sectional multi-level modelling approach for the main analyses, and further analyses using t-test and ANOVA.

Results

Results indicated that expression of fear was not a significant predictor of participants' reading comprehension performance (Model 1). However, when music condition was added (Model 2) in addition to expression of fear, a significant relationship between reading comprehension performance and music condition was found, showing better reading comprehension performance in the slow music condition than in the no music condition. Furthermore, there was a significant interaction effect between music condition and expression of fear on reading comprehension performance (Model 3). Importantly, not all individuals were affected by the music to the same extent, with the possibility that baseline level of fear being the key issue in influencing comprehension performance.

Conclusions

Considering both expression of fear and music condition is required to understand the combined effects on cognitive performance. Expression of fear during cognitive tasks such as reading could be an essential signal that interventions should be applied. Such strategies may be especially beneficial for task performers with higher baseline levels of fear and possibly provide us with insights for best practice and research implications in the field of reading comprehension among individuals with special needs.

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