Design and construction 125 Management 61 Purification 31 Materials 30 Quality control 28 Standards 28 Testing 26 Máis ... Water 26 Environmental aspects 25 Maintenance and repair 25 Planning 22 Safety measures 22 Production management 20 Sewage 20 Data processing 19 Electronic apparatus and appliances 19 Equipment and supplies 19 Integrated circuits 19 Buildings 17 Electric power systems 17 Mathematics 17 Measurement 17 Signal processing 17 Electronics 16 Project management 16 Electrical engineering 15 Six sigma (Quality control standard) 15 Transmission 15 Vibration 15 Construction industry 14 menos ...