Hi alainaho,
Kindly open wp-content\themes\angular\functions.php and find this line of code:
$avia_config['imgSize']['portfolio'] = array('width'=>465, 'height'=>346); // images for portfolio entries (2,3,4 column)
and replace it with:
$avia_config['imgSize']['portfolio'] = array('width'=>465, 'height'=>346, 'crop'=>true); // images for portfolio entries (2,3,4 column)
This will crop the images you have uploaded to make sure it will have uniform size without considering the aspect ratio of the image. Then kindly use the Regenerate plugin to regenerate all your images, http://wordpress.org/extend/plugins/regenerate-thumbnails/
I also noticed that some of the portfolio columns are too long which pushes the image below it. Try to make it shorter so they also have uniform size in space. Hope this helps.
Regards,
Ismael