Fig 10. Effect of phase difference of shakers on WOB and accelerations. A. Change in weight on bit in the bottom hole with time. B. Maximum acceleration along the drill-string. C. Root mean square acceleration along the drill-string v1 (protocols.io.kfbctin)

Power factor is the ratio of the real current or voltage received by a load to the root mean square (rms) value of the current or voltage that was supposed to be acquired by the same load. The fact that the two become different is due to the presence of reactive power in the circuit which gets dissipated.Improving the power factor means reducing the phase difference between voltage and current. Since majority of the loads are of inductive nature, they require some amount of reactive power for them to function. Therefore, for the better use of electrical appliances with minimum amount of electrical consumption, the power factor should necessarily be increased and should be brought near to 1. This can be easily done by the help of Automatic Power Factor Correction Capacitors and Active filters.

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Driving Comfort Evaluation for Manhole Covers and Pavement around Manholes

Advances in Materials Science and Engineering ◽

10.1155/2019/1293619 ◽

2019 ◽

Vol 2019 ◽

pp. 1-10 ◽

Cited By ~ 1

Author(s):

Quanman Zhao ◽

Zhigang Li ◽

Wenjun Hu ◽

Xianguang Meng ◽

Hui Zhang

Keyword(s):

Root Mean Square ◽

Influencing Factors ◽

Influence Factors ◽

Mean Square ◽

Height Difference ◽

Maximum Acceleration ◽

Driving Speed ◽

Longitudinal Slope ◽

Variation Characteristics ◽

Pavement Damage

In order to study the driving comfort and influencing factors when vehicles pass over manholes and pavement around manholes on an urban road, the deformation and vibration of the manhole cover were considered, a multidegree of freedom vibration model of the human-vehicle-manhole cover was established, and the variation characteristics of driving acceleration was analyzed. The root mean square of weighted acceleration was taken as the basic index, and driving comfort was evaluated based on ISO 2631-1-1997 standard. After that, 9 influencing factors were analyzed, such as driving speed, subsidence of manhole, manhole cover stiffness, and longitudinal slope. Then, grey correlation entropy analysis was used to evaluate the influencing factors, and the main factors were determined. The results showed that the maximum acceleration was 3.6 m/s2 when a vehicle was passing over a manhole cover under the basic parameters. At the same time, the root mean square of weighted acceleration was 0.975 m/s2 and driving comfort degree was “uncomfortable.” Driving direction and vibration of the manhole cover had little influence on driving comfort, while the remaining influencing factors had significant influence on that. The ranking of key influence factors on driving comfort was longitudinal slope, driving speed, height difference caused by pavement damage, height difference caused by manhole cover subsidence, tire stiffness, manhole stiffness, and tire damping. Therefore, in order to ensure driving comfort and safety, damage to pavement around manholes and manhole cover subsidence should be repaired in a timely manner.

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Frequency estimator by combination of phase difference method and interpolation algorithm

Journal of Algorithms & Computational Technology ◽

10.1177/1748301819833032 ◽

2019 ◽

Vol 13 ◽

pp. 174830181983303

Author(s):

Haitao Xu ◽

Leng Han ◽

Qingqing Huang ◽

Song Feng ◽

Junhui Cao

Keyword(s):

Lower Bound ◽

Root Mean Square ◽

Phase Difference ◽

Difference Method ◽

Small Scale ◽

Mean Square ◽

Interpolation Algorithm ◽

Cramer Rao Lower Bound ◽

Frequency Estimator ◽

Mean Square Errors

In the traditional time-shifting based phase difference method, considerable errors may be introduced by wrapped phase problem as long as translation coefficient tends to one even in a small-scale turbulence noise. In this paper, an improved frequency estimator is proposed to overcome the problem of wrapped phase by combination of phase difference method and interpolation algorithm. Compared with the traditional method of phase difference based on time-shifting, the improved algorithm can obtain an accurate estimate when translation coefficient exceeds one. Comparative studies were done by means of root-mean-square error over Cramer–Rao lower bound. According to the computer simulations, it is demonstrated that root-mean-square errors can cross Cramer–Rao lower bound if the translation coefficient is properly selected even in the case of the low signal-to-noise ratio, which implies that the proposed algorithm has a strong noise immunity. Finally, the advantage of the proposed algorithm is illustrated for the simulation signal which contained strong local random noise.

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