CUED Research Skills Course 2005 Issue Analysis and Hypothesis-driven Research Matthew Juniper...

CUED Research Skills Course 2005Issue Analysis and Hypothesis-driven Research

Matthew [email protected]

3:05 Introduction (lecture room 0)

3:10 Issue Trees

3:35 Hypothesis Trees

3:50 Issue Tree – group work (lecture rooms 0 and 4)

4:20 Discuss group work over tea

4:35 Applying issue analysis to PhDs (lecture room 0)

4:45 PhD Issue Trees – group work

5:15 Workshop (voluntary)

Issue Analysis and Hypothesis-driven Research



Issue Tree

Open question

What ? or How ?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



Issue Tree – example


How can I accumulate more money ?



Hypothesis Tree

Primary hypothesis

Why?Why?

Secondary hypothesis 2



Tertiary hypothesis 1b

Tertiary hypothesis 1a

Tertiary hypothesis 1c







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



Hypothesis Tree – example

Why?Why?

I can make money by blackmailing someone.



Issue Tree – group exercise

What can we do about global warming?


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 issuePrecise issues

can be tested by hypothesis

(We do not have time for

this now)Issues are

independent and

complete



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


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



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?Why?

or

Analysis:

PREMIX calculation of flame speed at differing mixture ratios of the two gases

CUED Research Skills Course 2005 Issue Analysis and Hypothesis-driven Research Matthew Juniper...

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