CUED Research Skills Course 2005 Issue Analysis and Hypothesis-driven Research Matthew Juniper 3:05Introduction (lecture room 0) 3:10Issue Trees 3:35Hypothesis Trees 3:50Issue Tree – group work (lecture rooms 0 and 4) 4:20Discuss group work over tea 4:35Applying issue analysis to PhDs (lecture room 0) 4:45PhD Issue Trees – group work 5:15 Workshop (voluntary) Issue Analysis and Hypothesis-driven Research

CUED Research Skills Course 2005 Issue Analysis and Hypothesis-driven Research Matthew Juniper Issue Tree Open question What ? or How ? Issue 2 Issue 1 Issue 3 Sub-issue 1b Sub-issue 1a Sub-issue 1c Sub-issue 2b Sub-issue 2a Sub-issue 2c Sub-issue 3b Sub-issue 3a Sub-issue 3c Precise issue Issues are independent and complete Precise issues can be tested by hypothesis

CUED Research Skills Course 2005 Issue Analysis and Hypothesis-driven Research Matthew Juniper Issue Tree – example What ? or How ? How can I accumulate more money ?

CUED Research Skills Course 2005 Issue Analysis and Hypothesis-driven Research Matthew Juniper Hypothesis Tree Primary hypothesis Why? Secondary hypothesis 2 Secondary hypothesis 1 Secondary hypothesis 3 Tertiary hypothesis 1b Tertiary hypothesis 1a Tertiary hypothesis 1c Tertiary hypothesis 2b Tertiary hypothesis 2a Tertiary hypothesis 2c Tertiary hypothesis 3b Tertiary hypothesis 3a Tertiary hypothesis 3c All the secondary hypotheses must be true for the primary hypothesis to be true All hypotheses must be precise statements Statement 3c(i) Statement 3c(ii) or

CUED Research Skills Course 2005 Issue Analysis and Hypothesis-driven Research Matthew Juniper Hypothesis Tree – example Why? I can make money by blackmailing someone.

CUED Research Skills Course 2005 Issue Analysis and Hypothesis-driven Research Matthew Juniper Issue Tree – group exercise What can we do about global warming? What ? or How ? Issue 2 Issue 1 Issue 3 Sub-issue 1b Sub-issue 1a Sub-issue 1c Sub-issue 2b Sub-issue 2a Sub-issue 2c Sub-issue 3b Sub-issue 3a Sub-issue 3c Precise issue Precise issues can be tested by hypothesis (We do not have time for this now) Issues are independent and complete

CUED Research Skills Course 2005 Issue Analysis and Hypothesis-driven Research Matthew Juniper What influences the re-light and light- round characteristics of an aeroplane engine the state of the fuel / air mixture in each burner aerodynamics the introduction of energy to the fuel / air mixture in each burner reactant properties the design of the network of burners in the engine The order in which they are turned on The distance between burners position of spark type of spark Issue Tree applied to an engineering problem – example What ? or How ? energy of spark duration of spark timing of spark burner face downstream composition temperature pressure composition temperature pressure pilot / main flame configuration flow shear at injection point oxidant fuel position of cooling air velocity of cooling air burners spark Axial view of combustion chamber in an aeroplane engine

CUED Research Skills Course 2005 Issue Analysis and Hypothesis-driven Research Matthew Juniper The fuels can be burned in a porous burner The velocities in the burner will not extinguish the flame The flame speed is high enough Can be mixed within the burner The pressure loss is sufficiently low The flow can be sufficiently premixed without auto-ignition The required flow speed is low enough The required porous surface area is small enough The geometrical constraints allow a large enough porous surface area The surface area required for complete combustion is small enough The flow can be mixed well The auto-ignition time is large enough Can be mixed before the burner The burner will fit into the available space The circumference of the whole burner is small enough for air to cool it sufficiently Hypothesis Tree applied to an engineering problem – example Why? or Analysis: PREMIX calculation of flame speed at differing mixture ratios of the two gases