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Words denoting abstract concepts constitute nearly half of human lexicon and serve as building blocks of the human culture. Since the advent of non-invasive neuroimaging techniques, great progress has been made in revealing the neurobiological foundation of concrete object and action concepts, yet it remains unclear how abstract concepts are stored and processed in the brain. Here we review recent development in this field, focusing on both theoretical perspectives and neuroimaging findings. We found that abstract concepts can be represented via linguistic and experiential information; the neural correlates of abstract concepts are partly in line with such a theoretical framework. Future studies are warranted to uncover the cognitive and neural mechanisms of language and experience in abstract word representation, which will help to deepen our understanding of general computational principles of the human conceptual system and to promote the development of the brain-like artificial intelligence.

A control mathematical model in pitch and yaw direction is presented to apply on missiles controlled by double-channel with style canard. Based on the mathematical model, the influence of deflection angle measurement error and actuator performance on actuator control is analyzed. The results show that the measure error of lean angle and actuator delay will produce control coupling in pitch and yaw direction and that will reduce control efficiency.

Traditional discrete method, converting order continuous system to order difference equation, describes system using the information of sampling points. But the system response in the time of will not be sufficient to describe the system when sampling period is much larger than the bandwidth of the system. By analyzing differential discrete method, our design gives an improvement to take out of the influence of the system bandwidth. In this method, order continuous system is transformed into order difference equation and the information of sampling points can be used to describe the system. It is proved that modified difference transformation is better in interference rejection than traditional difference transformation by comparing the simulation between the two transformations. The hardware implementation using TI's TMS320F2808 shows that modified difference transformation has a deviation close to round-off error based on simulation with a linear increase of operating time.