Speech-driven facial motion synthesis is a well explored research topic. However, little has been done to model expressive visual behavior during speech. We address this issue using a machine learning approach that relies on a database of speech-related high-fidelity facial motions. From this training set, we derive a generative model of expressive facial motion that incorporates emotion control, while maintaining accurate lip-synching. The emotional content of the input speech can be manually specified by the user or automatically extracted from the audio signal using a Support Vector Machine classifier.

We present a multiple‐satellite observation of the magnetic dip event during the substorm on 10 October 2013. The observation illustrates the temporal and spatial evolution of the magnetic dip and gives a compelling evidence that ring current ions induce the magnetic dip by enhanced plasma beta. The dip moves with the energetic ions in a comparable drift velocity and affects the dynamics of relativistic electrons in the radiation belt. In addition, the magnetic dip provides a favorable condition for the electromagnetic ion cyclotron (EMIC) wave generation based on the linear theory analysis. The calculated proton diffusion coefficients show that the observed EMIC wave can lead to the pitch angle scattering losses of the ring current ions, which in turn partially relax the magnetic dip in the observations. This study enriches our understanding of magnetic dip evolution and demonstrates the important role of the magnetic dip for the coupling of radiation belt and ring current.

Purpose -Knowledge governance is an organizational mechanism that formally and informally defines how the firm manages the activities related knowledge, thus it plays a significant influence on knowledge sharing. The purpose of this study is to analyze the impact of knowledge governance, including formal and informal knowledge governance, on knowledge sharing. Then the paper examines the mediating role of the guanxi effect on knowledge governance and knowledge sharing. Design/methodology/approach -Based upon this research, the authors chose to use the logical deductive approach for their hypotheses and analytical frameworks. Questionnaires and interviews were used to collect data from 339 employees in 39 Chinese strategic emerging firms. Finally, regression analysis and structure equation models (SPSS and AMOS) were used for data analysis and hypotheses testing. Findings -This study points to the impact that knowledge governance has on knowledge sharing based on the mediation of the guanxi effect in China. The results first show that knowledge governance, including formal and informal knowledge governance, plays a key role in knowledge sharing; second, that the guanxi effect partly mediates between informal knowledge governance and knowledge sharing; third, the guanxi effect plays a significant mediating role between formal knowledge governance and knowledge sharing. Research limitations/implications -This study presents a framework for Chinese strategic emerging industries to better understand the impact of knowledge governance upon knowledge sharing and thus enhance their firm's guanxi networks to maximize economic and social benefits. The managerial implications are that firms should strengthen knowledge governance to promote employee knowledge sharing and infuse a more harmonious atmosphere to strengthen the positive effects of guanxi among employees. Ultimately, Chinese firms must consider and encourage the benefits of the guanxi effect. This study only investigated 339 employees in 39 organizations located in the central China. It is limited by employees' cognition. In further research, the authors will identify more samples and develop a large-scale questionnaire to explore these impacts in more detail and thus enhance their current research. Originality/value -It is the first attempt in China to systematically investigate the impact of knowledge governance on knowledge sharing based on the mediation of the guanxi effect. The results provide a theoretical and methodological contribution to the study of knowledge governance and can thus improve managerial practice in an era of knowledge-based economies.

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The generation of a high‐frequency plasmaspheric hiss (HFPH) wave observed by Van Allen Probes is studied in this letter for the first time. The wave has a moderate power spectral density (∼10−6 nT2/Hz), with a frequency range extended from 2 to 10 kHz. The correlated observations of waves and particles indicate that HFPH is associated with the enhancement of electron flux during the substorm on 6 January 2014. Calculations of the wave linear growth rate driven by the fitted electron phase space density show that the electron distribution after the substorm onset is efficient for the HFPH generation. The energy of the contributing electrons is about 1–2 keV, which is consistent with the observation. These results support that the observed HFPH is likely to be generated locally inside the plasmasphere due to the instability of injected kiloelectron volt electrons.

Hall thrusters are widely used as space electric propulsion devices. Due to the complex plasma phenomenon and high computation cost, currently it is difficult to fully simulate the real physical process in Hall thrusters. Recently, Szabo and Taccogna have proposed two different methods to simplify and accelerate the simulation, respectively. In this paper, both these methods of acceleration are analysed and compared, and then a modified method of acceleration is proposed. In order to verify the modified method of acceleration, the influence of magnetic field gradient on plasma parameter distribution in the channel is simulated. The numerical results show that the magnetic field gradient can significantly alter the position of the ionization region and thruster performance.

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