Han Xiao

Based on ideology-infused psychological contract theory and cognitive evaluation theory, this study investigated the curvilinear relationship between ethical leadership and employee creativity. A curvilinear mediation model was proposed to explain the impact of ethical leadership on creativity, using employee intrinsic motivation as the mediator. Applying a two wave sampling design that consist 258 employees and their leaders, we found that employee creativity improved as ethical leadership increased from low to moderate levels. However, the employee creativity improvement was attenuated when ethical leadership increased from moderate to high levels. Furthermore, the study also revealed that employee intrinsic motivation partially mediated this curvilinear relationship. The theoretical and managerial implications are discussed.

Social semiotics is now widely regarded as one of the leading research areas. This study is the first attempt to present a holistic overview of social semiotics based on the data in the Web of Science core collection database from 2001 to 2020. The study investigates, among other issues, social semiotics’ publishing tendency, the most productive authors, countries, institutions, and hotspots. The results exhibit a steady rise in its publications and citations. The current analysis verifies the growing quantitative and qualitative research contributions and influences of this field. Furthermore, what the journals focus on are the innovative and contemporary themes, manifested predominantly in sign, multimodality, gender, experimental semiotics, advertising, culture, and social media, which involve a wide range of methodologies to make the research more acceptable and constructive. These results are expected to offer refreshing insights that inspire scholars in formulating scientific agendas and advising their research strategies, thereby facilitating substantial contributions to the domain.

Pantographs are important devices on high-speed trains. When a train runs at a high speed, concave and convex parts of the train cause serious airflow disturbances and result in flow separation, eddy shedding, and breakdown. A strong fluctuation pressure field will be caused and transformed into aerodynamic noises. When high-speed trains reach 300 km/h, aerodynamic noises become the main noise source. Aerodynamic noises of pantographs occupy a large proportion in far-field aerodynamic noises of the whole train. Therefore, the problem of aerodynamic noises for pantographs is outstanding among many aerodynamics problems. This paper applies Detached Eddy Simulation to conducting numerical simulations of flow fields around pantographs of high-speed trains which run in the open air. Time-domain characteristics, frequency-domain characteristics, and unsteady flow fields of aerodynamic noises for pantographs are obtained. The acoustic boundary element method is used to study noise radiation characteristics of pantographs. Results indicate that eddies with different rotation directions and different scales are in regions such as pantograph heads, hinge joints, bottom frames, and insulators, while larger eddies are on pantograph heads and bottom frames. These eddies affect fluctuation pressures of pantographs to form aerodynamic noise sources. Slide plates, pantograph heads, balance rods, insulators, bottom frames, and push rods are the main aerodynamic noise source of pantographs. Radiated energies of pantographs are mainly in mid-frequency and high-frequency bands. In high-frequency bands, the far-field aerodynamic noise of pantographs is mainly contributed by the pantograph head. Single-frequency noises are in the far-field aerodynamic noise of pantographs, where main frequencies are 293 Hz, 586 Hz, 880 Hz, and 1173 Hz. The farther the observed point is from the noise source, the faster the sound pressure attenuation will be. When the distance of two adjacent observed points is increased by double, the attenuation amplitude of sound pressure levels for pantographs is around 6.6 dB.

This study aimed to explore the influence the value modularity and a firm’s innovation performance, directly and indirectly, using knowledge management as mediating variable. Moreover, in this study, we used the resource integration ability as a moderator between the relationship value modularity and firm innovation performance. We collected data from the Chinese state-owned and state-controlled high-tech firms from 2011 to 2018. In this study, we used the gray comprehensive evaluation method to test the degree of value modularity, and hierarchical regression analysis is used to analyze the relationship among variables. The outcomes of this study indicate that value modularity and firm innovation performance has inverted U-shaped and significant association. Similarly, results also confirm that knowledge acquisition and knowledge internalization mediate the relationship between value modularity and firm innovation performance. The finding of this research also confirms that resource integration ability negatively affects the relationship between value modularity and firm innovation performance. This paper enriches the research of the value modularity and gives certain inspiration to knowledge management. At the end of this study, we also suggest some significant practical implications.

This paper is concerned with the optimal output feedback control problem for networked control systems with Markovian packet losses. In this paper, the packet losses occur both between the sensor and controller and between the controller and actuator. Moreover, the packet loss channels are described with two-state Markov chains. Since the precise state information cannot be obtained, thus an optimal recursive estimator is designed. Furthermore, by adopting the dynamic programming approach, we derive the optimal output feedback control, which is based on the solution to a given modified Riccati equation. The obtained results can be seen as an important implementation of the control theory for NCSs with unreliable communication channels.