Two short visits in October 2017

Hi, my wife and I are both UK passport holders and planning to be in Shanghai for two brief visits in October:
first visit:
2nd October - arrive Pudong International 1455
3rd October - deal Pudong International 1005
Second visit:
17th October - arrive Shanghai on a cruise ship 0700
19th October - depart Puding International 1315

Could you ever advise if our journeys could be covered by a 24 hour exemption and a 72 hour exemption or would we have to apply for visas please.

Kind regards