The low-noise optimisation method for gearbox in consideration of operating conditions

This paper presents a comprehensive procedure to calculate the steady dynamic response and the noise radiation generated from a stepping-down gearbox. In this process, the dynamic model of the cylindrical gear transmission system is built with the consideration of the time-varying mesh stiffness, gear errors and bearing supporting, while the data of dynamic bearing force is obtained through solving the model. Furthermore, taking the data of bearing force as the excitation, the gearbox vibrations and noise radiation are calculated by numerical simulation, and then the time history of node dynamic response, noise spectrum and resonance frequency range of the gearbox are obtained. Finally, the gearbox panel acoustic contribution at the resonance frequency range is calculated. Based on the conclusions from the gearbox panel acoustic contribution analyses and the mode shapes, two gearbox stiffness improving plans have been studied. By contrastive analysis of gearbox noise radiation, the effectiveness of the improving plans is confirmed. This study has provided useful theoretical guideline to the gearbox design

Predictive protocol of flocks with small-world connection pattern

By introducing a predictive mechanism with small-world connections, we propose a new motion protocol for self-driven flocks. The small-world connections are implemented by randomly adding long-range interactions from the leader to a few distant agents, namely pseudo-leaders. The leader can directly affect the pseudo-leaders, thereby influencing all the other agents through them efficiently. Moreover, these pseudo-leaders are able to predict the leader's motion several steps ahead and use this information in decision making towards coherent flocking with more stable formation. It is shown that drastic improvement can be achieved in terms of both the consensus performance and the communication cost. From the industrial engineering point of view, the current protocol allows for a significant improvement in the cohesion and rigidity of the formation at a fairly low cost of adding a few long-range links embedded with predictive capabilities. Significantly, this work uncovers an important feature of flocks that predictive capability and long-range links can compensate for the insufficiency of each other. These conclusions are valid for both the attractive/repulsive swarm model and the Vicsek model.Comment: 10 pages, 12 figure

Ethics-related practices in Internet-based applied linguistics research

Drawing on an analytic framework developed from ethical research guidelines and the relevant literature, this study analyzes and discusses the ways ethical issues were addressed by authors of 72 relevant journal articles on online self-representation in the field of applied linguistics. The results illustrate how researchers undertook efforts to fulfill ethical responsibilities in Internet-based research. They show how researchers’ self-narrated concerns and contextual conditions have mediated ethics-related research practices as reported in these studies. The results indicate the need for researchers to enhance critical awareness and assessment of potential ethical issues when conducting Internet-based research. Such critical awareness is essential for researchers to initiate and sustain an ongoing dialogue concerning ethics-related research practices in Internet-based applied linguistics research

A near-field error sensing strategy for compact multi-channel active sound radiation control in free field

© 2019 Acoustical Society of America. Noise reduction performance of a compact active sound radiation control system is significantly affected by locations of the error microphones which are required to be installed near the primary source. In this paper, near-field error sensing for multi-channel active radiation control systems in free field is investigated, and it is found that the optimal locations of error sensors for minimizing the sum of squared sound pressure are between the primary source and the secondary sources distributed uniformly on a sphere surface surrounding the primary source. Both simulation and experiment results show that the optimal locations of error microphones are independent of the type of primary source when there are sufficient secondary sources. These optimal locations remain unchanged at low frequencies and move toward secondary sources when the secondary source number increases. Therefore, for active radiation control applications in low frequency range, a compact multi-channel system can be developed by locating error microphones between the primary source and secondary sources

Solutions to the Jaynes-Cummings model without the rotating-wave approximation

By using extended bosonic coherent states, the solution to the Jaynes-Cummings model without the rotating-wave approximation can be mapped to that of a polynomial equation with a single variable. The solutions to this polynomial equation can give all eigenvalues and eigenfunctions of this model with all values of the coupling strength and the detuning exactly, which can be readily applied to recent circuit quantum electrodynamic systems operating in the ultra-strong coupling regime.Comment: 6 pages,3 figure

Error microphone location study for an eight-channel ANC system in free space

© 25th International Congress on Sound and Vibration 2018, ICSV 2018: Hiroshima Calling. All rights reserved. The location of error microphones is one key factor that determines the performance of a multichannel active noise control (ANC) system in terms of global sound power reduction when the number and the location of secondary sources are fixed. In a single channel ANC system, the optimal error microphone location is on a line that is nearly perpendicular to the secondary and primary source axis and closer to the secondary source. This paper investigates the optimal location of the error microphones in an 8-channel ANC system in free space. It is demonstrated that good noise reduction performance can be achieved by placing the error microphones between the primary source and secondary sources and closer to the secondary sources in the low frequency range. Experiments conducted on a gearbox for low frequency noise control show that the averaged sound level reduction at the observation locations 2 meters away is 5.2 dB when the error microphones are placed at 0.2 m inside the secondary source surface

Effect of user tastes on personalized recommendation

In this paper, based on a weighted projection of the user-object bipartite network, we study the effects of user tastes on the mass-diffusion-based personalized recommendation algorithm, where a user's tastes or interests are defined by the average degree of the objects he has collected. We argue that the initial recommendation power located on the objects should be determined by both of their degree and the users' tastes. By introducing a tunable parameter, the user taste effects on the configuration of initial recommendation power distribution are investigated. The numerical results indicate that the presented algorithm could improve the accuracy, measured by the average ranking score, more importantly, we find that when the data is sparse, the algorithm should give more recommendation power to the objects whose degrees are close to the users' tastes, while when the data becomes dense, it should assign more power on the objects whose degrees are significantly different from user's tastes.Comment: 8 pages, 4 figure