The science of ground and pound isn’t really broken down the same way Brazilian Jiu Jitsu, Muay Thai, and other arts are. There is a lot of grey area that is still out there in MMA.
The half guard is particularly a tricky position. From a pure BJJ standpoint, both the top and bottom have submission opportunities and a pretty equal ability to better their position. When you add MMA to the picture, things change. The person on the top is definitely at an advantage.
Here is an example of how to use the top position to open up strikes on your opponent. Keep in mind that you want to keep a strong base when you are putting your opponents arm between your legs. You are basically giving them a sweep if you let your hips become light.