Abstract　  

   Pulsars are precise cosmic clocks and compact objects that are very useful in the study of fundamental physics.

   I would like to talk about the two aspects of my researches: 1. Pulsar timing: in particular, the 21 year timing of one of the most precisely measured pulsar binary: PSR J1713+0747, and its applications in testing theories of gravitation, most notably, the best extra-solar system test of the gravitational constant. 2. Pulsar searches: I developed a novel image-pattern-based deep-neural-network artificial intelligence (the PICS AI) for finding pulsars. The AI program improves efficiency of pulsar searches by a factor of more than 100. It has been applied to several major pulsar surveys using different telescopes, including the most sensitive Arecibo pulsar survey, and has helped discovering more than 15 pulsars. The AI system is also being applied to search for transient radio signals from Radio Transient neutron stars (RRATs) and Fast Radio Bursts (FRBs).